Synthesis of Fe3O4 encapsulated with lemon yellow for application in magnetic particle inspection

Synthesis of Fe3O4 encapsulated with lemon yellow for application in magnetic particle inspection | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Synthesis of Fe3O4 encapsulated with lemon yellow for application in magnetic particle inspection Zhiqi Liang, Zhili Zhang, Decai Li This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4864962/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 10 Mar, 2025 Read the published version in Journal of Nondestructive Evaluation → Version 1 posted 9 You are reading this latest preprint version Abstract Magnetic particle inspection, a widely used nondestructive testing method, is employed to detect surface defects in ferromagnetic materials due to its ease of operation, low cost, and high efficiency. In this study, Fe 3 O 4 hollow nanospheres were synthesized by a solvothermal method. Lemon yellow (LY) pigments were successfully encapsulated on the surface of these magnetic nanospheres using E51 epoxy resin. The synthesized Fe 3 O 4 /E51/LY composite material was characterized in terms of its microscopic morphology, physical phase, and structural properties. The adsorption mechanism of the fluorescent materials on the particle surface was analyzed. Additionally, the photoluminescence and magnetic properties of the composite were tested and evaluated. A magnetic particle inspection test bench was then established to detect defects in the workpiece. The composite exhibited a saturation magnetization of 53.22 emu/g and emitted yellow-green fluorescence at 525 nm under ultraviolet light. The surface defects of the workpiece were accurately detected using magnetic fluorescent particles. Nanospheres Fe3O4 Luminescence Magnetic Magnetic particle inspection Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 1. Introduction Magnetic particle inspection (MPI) is a non-destructive testing (NDT) method that detects surface or near-surface defects in ferromagnetic materials by the accumulation of magnetic fluorescent particles at sites of magnetic flux leakage [ 1 , 2 ]. It is particularly effective for identifying small surface defects that are not easily visible to the naked eye. Due to its fluorescent defect display, low cost, high efficiency, and accuracy, fluorescent magnetic particle inspection is widely used in the inspection of metal materials and finished products [ 3 ]. Magnetic fluorescent composites have potential applications in drug delivery, non-destructive testing, and as fluorescent probes due to their combined photoluminescent and magnetic properties [ 4 – 6 ]. In fluorescent magnetic particle inspection, these composites must exhibit a strong magnetic response under a magnetic field and emit bright yellow-green fluorescence at approximately 540 nm under UV light. Typically, magnetic fluorescent composites are synthesized by integrating magnetic particles with fluorescent molecules through chemical adsorption or physical encapsulation [ 7 , 8 ]. Fe 3 O 4 particles, among the most representative magnetic particles, can be synthesized through chemical co-precipitation, solvothermal, and sol-gel methods [ 9 – 11 ], all of which yield particles with excellent paramagnetic properties and high saturation magnetization. Fluorescent materials used in these composites can be categorized into azo organic fluorescent pigments and rare earth organic fluorescent materials [ 12 ]. Azo fluorescent materials, organic compounds containing azo groups (-N = N-), emit bright fluorescence under UV light and are characterized by high fluorescence quantum yield, good photostability, chemical stability, and low toxicity [ 13 ]. Rare earth organic fluorescent materials, such as those containing Eu 3+ and Tb 3+ , offer advantages like longer fluorescence lifetimes and narrow emission peaks [ 14 ]. However, their luminescence is susceptible to quenching due to interference from other groups in the luminescence center, and they are relatively expensive. Liang et al. [ 15 , 16 ] encapsulated HMDA[Eu(DBM) 4 ] and Y 2 O 2 S:Eu 3+ fluorescent materials onto the surface of Fe 3 O 4 particles using solvothermal and hydrothermal methods, respectively. The resulting red fluorescent magnetic composites exhibited saturation magnetization strengths of 51.2 emu/g and 18.9 emu/g, respectively, with good stability and discriminative ability, effectively performing MPI on ferromagnetic materials. De Melo et al. [ 17 ] synthesized a composite of fluorescent cadmium telluride quantum dots and functionalized maghemite nanoparticles (MghNPs@QDs) through electrostatic adsorption using cetyltrimethylammonium bromide as a linker, demonstrating excellent performance in non-destructive MPI. A significant challenge in synthesizing magnetic fluorescent composites is ensuring that the fluorescent material is securely encapsulated on the surface of the magnetic particles. The fluorescent material should remain firmly attached to the particles to guarantee effective MPI [ 18 ]. In this paper, Fe 3 O 4 /E51/LY magnetic luminescent particles were synthesized by coating LY organic fluorescent pigments onto the surface of Fe 3 O 4 hollow nanospheres using epoxy resin. The Fe 3 O 4 hollow nanospheres were synthesized via the solvothermal method. The structure, microscopic morphology, luminescence, and magnetic properties of the Fe 3 O 4 /E51/LY composite were characterized. Additionally, MPI of the workpiece was conducted using the composite. 2. Materials and methods 2.1. Materials Ferric chloride hexahydrate (FeCl 3 ·6H 2 O, 99%), sodium acetate anhydrous (CH 3 COONa, 99%), ethylene glycol ((CH 2 OH) 2 , 98%), E51 epoxy resin (E51), lemon yellow (C 16 H 9 N 4 O 9 S 2 Na 3 , LY, 99%), and sodium dodecylbenzene sulfonate (C 12 H 25 SO 3 Na, 98%) were purchased from Shanghai Macklin Biochemical Technology Co. Ltd. All reagents were used without further purification. 2.2. Synthesis of Fe 3 O 4 nanospheres FeCl 3 ·6H 2 O, C 12 H 25 SO 3 Na, CH 3 COONa, and (CH 2 OH) 2 were sequentially added to the reactor in a molar ratio of 1:0.003:3:91.98 and thoroughly dispersed. The prepared solution was sealed in a muffle furnace and allowed to react slowly at 200 ℃ for 15 hours. After the reaction, the precipitate was washed with deionized water to obtain the magnetic nanospheres. 2.3. Synthesis of Fe 3 O 4 /E51/LY composite 0.5 g of magnetic nanospheres, 0.5 g of LY were thoroughly mixed with 1 mL of E51 epoxy resin emulsion. Then, 0.2 mL of hardener was added, stirred well, and left to cure for 8 hours. The resulting block material was placed in a 30 mL ball mill jar with ceramic balls and ground using a ball mill. The magnetic fluorescent composite was obtained by washing the powder with deionized water after ball milling. 2.4. Characterization The microscopic morphology of the magnetic nanospheres, fluorescent materials, and magnetic fluorescent composite was observed using scanning electron microscope (SEM, Zeiss Gemini-300). The material structures and molecular groups of the samples were analyzed using an X-ray diffractometer (XRD, Rigaku D/MAX) and a Nicolet iS20 Fourier transform infrared spectrometer (FTIR), respectively. The photoluminescence spectra, decay curves, and variable temperature fluorescence curves of the samples were measured using an Edinburgh steady-state and transient fluorescence spectrometer. The magnetic properties of the samples were characterized using a MicroSense EZ9 sample vibration magnetometer. The microscopic morphology of the magnetic particles moving under a magnetic field was observed using an Olympus GX41 optical microscope. 3. Results and Discussion 3.1. Morphological and structural characterization of Fe 3 O 4 /E51/LY composite The material structure of the sample can be inferred from the XRD data results. In the XRD pattern of Fig. 1 a, the X-ray powder diffraction patterns of E51 and LY show a broad diffuse scattering peak near 20° and no peaks indicative of crystalline phases, indicating that the material exists in an amorphous form. The diffraction pattern of Fe 3 O 4 hollow nanospheres has eight narrow peaks at 18.46°, 30.28°, 35.57°, 37.2°, 43.21°, 53.55°, 57.15°, and 62.68°, corresponding to (111), (220), (311), (222), (400), (422), (511), and (440) of Fe 3 O 4 (JCPDS No. 19–0629) [ 15 ]. The diffraction peaks of Fe 3 O 4 /E51/LY composite are similar to those of Fe 3 O 4 nanospheres, except that these peaks are slightly weaker. FTIR analyses were conducted to confirm the coating of the magnetic particles with fluorescent material using resin. In the spectra of E51 and LY shown in Fig. 1 b, the peaks at 2932 and 2860 cm − 1 can be attributed to the bending vibration of -CH. The peaks at 1600, 1535, and 1480 cm − 1 correspond to the stretching vibration of the benzene ring in the E51 and LY molecules. In the spectrum of E51, the characteristic peak of the epoxy group appears at 913 cm − 1 [ 19 ]. The characteristic absorption peak at 1070 cm − 1 is attributed to the stretching vibration of -SO 3 − in the LY molecule. The Fe-O group in Fe 3 O 4 is located at 575 cm − 1 . All these characteristic peaks are present in the spectral curves of the Fe 3 O 4 /E51/LY composite. The SEM image of Fe 3 O 4 particles synthesized by the solvothermal method shows that their morphology consists essentially of hollow spheres with a particle size of approximately 450 nm, as depicted in Fig. 2 a. Figure 2 b and 2 c show the microscopic morphology of the LY pigments and E51 resin, respectively. Combined with XRD analysis, it is evident that both LY and E51 resin are in amorphous form. The Fe 3 O 4 /E51/LY composite was obtained by coating the surface of the nanospheres with the fluorescent pigment LY using resin. The particles were mixed and bound together by the resin with the fluorescent pigment, as shown in Fig. 2 d. Elemental analysis of the microscopic surface of the material was performed using EDS-mapping. The distribution of the elements N, C, S, Na, O, and Fe in the composite is shown in Figs. 2 f- 2 k, along with the mass percentage of these elements (Fig. 2 l). Fe 3 O 4 nanospheres can be prepared by heating the reaction solution in a Teflon reactor at high temperature by the solvothermal method. According to the Ostwald ripening mechanism, at high temperature and pressure, the tiny particles inside the nanospheres dissolve, while Fe 3 O 4 particles generated in the solution accumulate on the outer surface of the nanospheres. Due to the difference in surface energy between the inside and outside of the nanospheres, hollow nanospheres are gradually formed [ 20 ]. The E51 epoxy resin molecules contain various polar groups and reactive epoxy groups, which exhibit strong adsorption effects on the oxygen atoms on the surface of the nanospheres and on groups such as C = O and -SO 3 − in the LY fluorescent pigment molecules. The resin and amine curing agent undergo a crosslinking polymerization reaction to form Fe 3 O 4 /E51/LY composite blocks. After ball milling and crushing the blocks, most of the LY fluorescent pigments remain stably encapsulated on the surface of Fe 3 O 4 nanospheres due to the resin’s adsorption. The encapsulation scheme is illustrated in Fig. 3 . 3.2 Luminescence properties of Fe 3 O 4 /E51/LY composite The results measured by fluorescence spectrometer, shown in Fig. 4 , reveal the luminescence properties of LY fluorescent pigments and the Fe 3 O 4 /E51/LY composite. The LY fluorescent pigment exhibits a broad absorption peak between 325–500 nm (Fig. 4 a). Under an excitation wavelength of 430 nm, LY emits a strong yellow-green fluorescence with a primary peak wavelength of 525 nm. The emission spectra of Fe 3 O 4 /E51/LY show a blue shift compared to that of LY, which is hypothesized to be caused by electrostatic interaction between the LY fluorescent pigment molecules and the E51 resin molecules. In the LY molecule, two benzene rings are linked by an azo bond -N = N- to form a conjugated structure, and the molecule contains numerous conjugated double bonds, allowing LY to effectively absorb photons and emit fluorescence [ 21 ]. The comparison of the luminescence of Fe 3 O 4 /E51/LY under visible and UV light is shown in the inset of Fig. 4 b. The fluorescence intensity and fluorescence lifetime of the Fe 3 O 4 /E51/LY composite are reduced due to the quenching effect of the black Fe 3 O 4 powder [ 22 ]. The decay curve data of the samples in Fig. 4 c were fitted with a biexponential decay function, yielding average fluorescence lifetimes of 4.25 ns for LY and 3.10 ns for Fe 3 O 4 /E51/LY [ 15 ]. The fluorescence spectra of Fe 3 O 4 /E51/LY were further tested at different temperatures with an excitation wavelength of 430 nm, as shown in Fig. 4 d. The intensity of the primary peak in the emission spectra gradually decreased when heated from room temperature to 150 ℃, indicating temperature-induced quenching of the luminescence. Despite the reduction, the material still exhibits significant fluorescence intensity at 150 ℃, demonstrating its suitability for use in complex temperature environments. The phenomenon of luminescence observed in fluorescent materials is due to the transitions of electrons between different orbitals within their molecules. This results in a difference between the wavelengths of the excitation and emission peaks, known as the Stokes shift (Fig. 5 a) [ 23 ]. Figure 5 b shows the Jablonski energy level diagram of photoluminescence [ 24 ]. Upon absorption of UV light with an energy of hν A , the electrons in the molecule transfer from the ground state energy level (S 0 ) to the unstable excited states (S 1 or S 2 ). Being in an unstable state, the electrons will return to the stable ground state. During the internal energy transfer process, the electrons transfer back to S 1 by vibrational relaxation or radiative relaxation after absorbing light energy. From the S 1 energy level, a non-radiative transition or emission of light with an energy of hν F occurs, which is called fluorescence. Another form of electron transition is intersystem crossing, where the transition from the triplet state to the ground state is accompanied by a non-radiative transition or emission of light with an energy of hν P , known as phosphorescence. The luminescence of the fluorescent pigment LY is classified as fluorescence. Figure 5 c shows the CIE 1931 colorimetric diagram developed by the Commission Internationale de l'Éclairage. The curved contour line of the CIE chromaticity diagram represents the trajectory of all visible wavelengths [ 25 ]. The number along the line indicates the dominant wavelength of visible light. The color coordinates of the LY fluorescent pigment and the Fe 3 O 4 /E51/LY composite are ( x = 0.25, y = 0.72) and ( x = 0.19, y = 0.76), respectively. 3.3 Magnetic properties of Fe 3 O 4 /E51/LY The magnetic properties of Fe 3 O 4 magnetic nanospheres and Fe 3 O 4 /E51/LY magnetic luminescent composite were investigated using a VSM. The measured hysteresis loops are shown in Fig. 6 a. The Fe 3 O 4 hollow nanospheres demonstrated good paramagnetic properties and high saturation magnetization strength, with saturation magnetization values of 85.54 emu/g for Fe 3 O 4 and 53.22 emu/g for Fe 3 O 4 /E51/LY. The remanence of the two was measured to be 8.64 emu/g and 2.16 emu/g, respectively, under a magnetic field of ± 2 T, and the coercivities were 77.55 Oe and 23.02 Oe, respectively. The magnetic suspension of the Fe 3 O 4 /E51/LY magnetic luminescent composite under UV light is shown in the inset. The magnetic luminescent particles in the suspension are attracted to the inner wall of the cuvette by a magnet, emitting a bright yellow-green color. To gain a clearer understanding of the magnetic response properties of the Fe 3 O 4 /E51/LY magnetic luminescent composite, optical microscopy coupled with a double-pole electromagnet was used to observe the motion of Fe 3 O 4 /E51/LY particles under a uniform magnetic field. As shown in Fig. 6 b and 6 c, the Fe 3 O 4 /E51/LY particles are randomly distributed when the external magnetic field strength is zero, appearing yellow-green under UV light irradiation. When an external magnetic field is applied, the particles exhibit mutual attraction, agglomerating to form short chains. The direction of the chain length of the magnetic agglomerates aligns with the direction of the external magnetic field. As shown in Fig. 6 d and 6 e, when the uniform magnetic field strength is increased to 0.2 T, several short magnetic chains rapidly assemble to form a thick, long magnetic chain parallel to the magnetic field direction. Under UV light, a magnetic chain of approximately 500 µm in length with yellow-green fluorescence can be observed. 3.4 Magnetic particle inspection The synthesized Fe 3 O 4 /E51/LY magnetic luminescent composite needs to be calibrated for concentration and tested for defect detection sensitivity prior to MPI. The well-dispersed Fe 3 O 4 /E51/LY magnetic suspension was poured into a centrifuge tube placed in a holder and left undisturbed for 1 hour in the absence of a magnetic field to allow the particles in the magnetic suspension to precipitate. As shown in Fig. 7 a, the precipitated volume at the bottom of the centrifuge tube gradually increases. When the volume of precipitation is less than 0.1 mL, a certain amount of Fe 3 O 4 /E51/LY powder must be replenished to maintain the suspension’s effectiveness for MPI. This method is used to calibrate the concentration of the magnetic suspension after it has been used for flaw detection [ 26 ]. The sensitivity of the Fe 3 O 4 /E51/LY fluorescent magnetic composite was tested using a test piece shim, as shown in Fig. 7 b. A 30 µm deep artificial defect was engraved on the surface of the test piece, which was then placed face down on an iron block. The calibrated magnetic suspension was sprayed on the back surface of the test piece while an alternating magnetic field was applied to the iron block for magnetization [ 27 ]. Due to magnetic flux leakage at the defects, the magnetic field intensity is higher at the defect edges. Under the magnetic field, the Fe 3 O 4 /E51/LY particles rapidly formed a yellow-green pattern on the back side of the test piece, indicating that the Fe 3 O 4 /E51/LY composite possesses good discrimination and sensitivity, accurately revealing the location of the defects. Additionally, MPI experiments were conducted on a gear workpiece using the Fe 3 O 4 /E51/LY composite. The test bench model is illustrated in Fig. 8 a. The experiments employed a method combining axial and circumferential magnetic fields. A current passed through the iron core connecting the electrodes on both sides, creating a circumferential magnetic field around it. This setup could detect axial surface defects on a rotary workpiece. Meanwhile, the ring solenoid generated a magnetic field parallel to the axial direction, allowing for the detection of surface defects perpendicular to the axial direction. A simple MPI test bench was constructed based on this model (Fig. 8 b). The axial and circumferential magnetic fields were controlled by two AC power supplies on the left and right, respectively. The steps of MPI included: preparation of the magnetic suspension, surface pretreatment of the workpiece, magnetization of the workpiece, spraying of the magnetic suspension, defect observation, demagnetization of the workpiece, and post-processing of the workpiece. Under UV light, yellow-green magnetic particle indications on the workpiece surface revealed surface defects. A camera was used to capture images of these defects for further analysis. As shown in Figs. 8 c- 8 f, cracks between the tooth roots of the cast iron gear were clearly observed. These cracks, viewed under a fluorescence microscope, showed Fe 3 O 4 /E51/LY magnetic luminescent particles accumulating in the cracks due to magnetic flux leakage. The average width of the cracks between the tooth roots was about 50 µm. The Fe 3 O 4 /E51/LY magnetic luminescent composite effectively and accurately detected the defects on the gear surface. 4. Conclusions In conclusion, the Fe 3 O 4 /E51/LY magnetic fluorescent composite was synthesized using a resin-binding method, achieving a saturation magnetization strength of 53.22 emu/g and exhibiting good paramagnetic properties. The material’s excitation and emission wavelengths are 430 nm and 525 nm, respectively, with a fluorescence lifetime of 3.1 ns. The epoxy groups on the resin molecules effectively adsorb the azo fluorescent pigment molecules onto the surface of the nanospheres, preventing detachment. Under UV light, the Fe 3 O 4 /E51/LY composite demonstrates high discrimination and sensitivity, making it suitable for applications in MPI. Declarations Competing interest The authors declare that they have no conflict of interest. Funding This work was supported by Fundamental Research Funds for the Central Universities (2024JBZY027) and the National Natural Science Foundation of China (No. 51927810). Author Contribution Zhiqi Liang drew all the figures and wrote the main manuscript. Zhili Zhang and Decai Li supervised and revised the paper. All authors reviewed the manuscript. Data availability The datasets generated during and/or analyzed during the current study are available from the corresponding authors on reasonable request. References Wu, Q., Dong, K., Qin, X., et al.: Magnetic particle inspection: Status, advances, and challenges-demands for automatic non-destructive testing[J], p. 103030. 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Supplementary Files Graphicalabstract.jpg Cite Share Download PDF Status: Published Journal Publication published 10 Mar, 2025 Read the published version in Journal of Nondestructive Evaluation → Version 1 posted Editorial decision: Revision requested 01 Jan, 2025 Reviews received at journal 01 Jan, 2025 Reviewers agreed at journal 01 Jan, 2025 Reviews received at journal 07 Nov, 2024 Reviewers agreed at journal 18 Oct, 2024 Reviewers invited by journal 18 Oct, 2024 Editor assigned by journal 23 Sep, 2024 Submission checks completed at journal 07 Aug, 2024 First submitted to journal 05 Aug, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4864962","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":337449747,"identity":"ca42d465-18b9-4476-9771-9392b532f019","order_by":0,"name":"Zhiqi Liang","email":"","orcid":"","institution":"Beijing Jiaotong University","correspondingAuthor":false,"prefix":"","firstName":"Zhiqi","middleName":"","lastName":"Liang","suffix":""},{"id":337449749,"identity":"d3c14d0f-d5a3-46d6-b1cc-dd648342af3c","order_by":1,"name":"Zhili Zhang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA4ElEQVRIie3RsQrCMBCA4SuBdKm4RkT7Ci0dFHyZdsqizg61BArpJL5KN3WLFOJScXXUxU1wdVBsrXOIm2D+5Zb7IEcATKZfzAZcj74Hop5Ig6CGBB4UX5Iob7Y1iJval9N9Pacr6yAJzEYRs/dCSawUqL8od5MNKzCBkkbMmYbqdyGQpMXlJBcVsXgRMeJ4SoKRxTsPLqn3Jk8N4iCEuy0ehw1hGoQgjLs9LvzqlmAYShpwZ6wmbpZdOleeuAOyPR9v8ai3tEs1+VR9IxEAYX2dzn5VAtBmmrsmk8n0d70A8PFAznvkw7MAAAAASUVORK5CYII=","orcid":"","institution":"Beijing Jiaotong University","correspondingAuthor":true,"prefix":"","firstName":"Zhili","middleName":"","lastName":"Zhang","suffix":""},{"id":337449751,"identity":"720fa38c-151b-4327-acec-3a0c126276ae","order_by":2,"name":"Decai Li","email":"","orcid":"","institution":"Tsinghua University","correspondingAuthor":false,"prefix":"","firstName":"Decai","middleName":"","lastName":"Li","suffix":""}],"badges":[],"createdAt":"2024-08-06 02:32:14","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4864962/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4864962/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10921-025-01175-z","type":"published","date":"2025-03-10T15:57:47+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":63919471,"identity":"910a9919-227b-46fa-b600-eadcd0d12718","added_by":"auto","created_at":"2024-09-03 18:59:25","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":463378,"visible":true,"origin":"","legend":"\u003cp\u003eXRD patterns and FTIR spectra of E51, LY, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e, and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY.\u003c/p\u003e","description":"","filename":"Figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4864962/v1/4de9ffc9f3a496ae48687b5b.jpg"},{"id":63919464,"identity":"05d73bdc-0a5b-47bb-abb3-643b1df97713","added_by":"auto","created_at":"2024-09-03 18:59:24","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1742474,"visible":true,"origin":"","legend":"\u003cp\u003eThe SEM images of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e (a), LY (b), E51 (c), and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY composite (d). The EDS-mapping (e-k) and the elemental distribution (l) of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY composite.\u003c/p\u003e","description":"","filename":"Figure2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4864962/v1/906634b0188a89a51f288b70.jpg"},{"id":63920057,"identity":"5bb1eea8-124c-4e71-b20f-6d2db8041c01","added_by":"auto","created_at":"2024-09-03 19:15:24","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":748743,"visible":true,"origin":"","legend":"\u003cp\u003eThe encapsulation schematic diagram of the Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY composite.\u003c/p\u003e","description":"","filename":"Figure3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4864962/v1/4063e4a246e807b15c350e9d.jpg"},{"id":63919470,"identity":"a6ac7c8a-2826-4857-b32b-91a0fc85198e","added_by":"auto","created_at":"2024-09-03 18:59:24","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":996182,"visible":true,"origin":"","legend":"\u003cp\u003eThe PL spectra (a and b), decay curves (c), and variable temperature fluorescence curves (d) of LY and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY.\u003c/p\u003e","description":"","filename":"Figure4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4864962/v1/4459f0f864f505076c57fbce.jpg"},{"id":63919469,"identity":"449ec009-31e7-4a54-aec8-be116d4bdb63","added_by":"auto","created_at":"2024-09-03 18:59:24","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":479103,"visible":true,"origin":"","legend":"\u003cp\u003eStokes’ observation (a) and the Jablonski energy level diagram (b) of photoluminescence, (c) the CIE chromaticity diagram for LY and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY.\u003c/p\u003e","description":"","filename":"Figure5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4864962/v1/5cca95bc8edc3c327a45b589.jpg"},{"id":63919766,"identity":"0ff6bb83-0fd2-4710-ae81-ec484954f6dc","added_by":"auto","created_at":"2024-09-03 19:07:24","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":436141,"visible":true,"origin":"","legend":"\u003cp\u003e(a) The hysteresis loops of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY, (b)-(e) Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY composite under the optical microscope (200×).\u003c/p\u003e","description":"","filename":"Figure6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4864962/v1/7a690d25be41e3b298f6355b.jpg"},{"id":63919768,"identity":"b91a4d4f-de58-4822-a0a5-f3b4fca701ea","added_by":"auto","created_at":"2024-09-03 19:07:24","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":641264,"visible":true,"origin":"","legend":"\u003cp\u003eConcentration determination of magnetic fluorescent particles (a). Sensitivity of fluorescent magnetic materials using test piece shim (b).\u003c/p\u003e","description":"","filename":"Figure7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4864962/v1/84f2d4f56049f0b332fcab81.jpg"},{"id":63919467,"identity":"fa839ff4-90fd-4deb-bdf2-fc417e4b1c84","added_by":"auto","created_at":"2024-09-03 18:59:24","extension":"jpg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":710097,"visible":true,"origin":"","legend":"\u003cp\u003e(a) The model of the MPI test bench. The red dashed lines in the figure indicate directions of the circumferential and axial magnetic field. (b) MPI test of gears. (c)-(f) Surface cracks on the gear with aggregated Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY fluorescent magnetic particles observed under a fluorescence microscope.\u003c/p\u003e","description":"","filename":"Figure8.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4864962/v1/987e805f005522ecb6786153.jpg"},{"id":78689001,"identity":"3f1a4388-8510-456c-9b18-b5f94679710d","added_by":"auto","created_at":"2025-03-17 16:09:58","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":6892241,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4864962/v1/e5510a63-c814-4d88-a7f7-9a9d3fd61ed7.pdf"},{"id":63919462,"identity":"033fbf8d-9a67-4267-960f-d387c5dfb41e","added_by":"auto","created_at":"2024-09-03 18:59:24","extension":"jpg","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":211081,"visible":true,"origin":"","legend":"","description":"","filename":"Graphicalabstract.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4864962/v1/5dc4ad3f59e142b435f3902d.jpg"}],"financialInterests":"No competing interests reported.","formattedTitle":"Synthesis of Fe3O4 encapsulated with lemon yellow for application in magnetic particle inspection","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eMagnetic particle inspection (MPI) is a non-destructive testing (NDT) method that detects surface or near-surface defects in ferromagnetic materials by the accumulation of magnetic fluorescent particles at sites of magnetic flux leakage [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. It is particularly effective for identifying small surface defects that are not easily visible to the naked eye. Due to its fluorescent defect display, low cost, high efficiency, and accuracy, fluorescent magnetic particle inspection is widely used in the inspection of metal materials and finished products [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eMagnetic fluorescent composites have potential applications in drug delivery, non-destructive testing, and as fluorescent probes due to their combined photoluminescent and magnetic properties [\u003cspan additionalcitationids=\"CR5\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. In fluorescent magnetic particle inspection, these composites must exhibit a strong magnetic response under a magnetic field and emit bright yellow-green fluorescence at approximately 540 nm under UV light. Typically, magnetic fluorescent composites are synthesized by integrating magnetic particles with fluorescent molecules through chemical adsorption or physical encapsulation [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e particles, among the most representative magnetic particles, can be synthesized through chemical co-precipitation, solvothermal, and sol-gel methods [\u003cspan additionalcitationids=\"CR10\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], all of which yield particles with excellent paramagnetic properties and high saturation magnetization. Fluorescent materials used in these composites can be categorized into azo organic fluorescent pigments and rare earth organic fluorescent materials [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Azo fluorescent materials, organic compounds containing azo groups (-N\u0026thinsp;=\u0026thinsp;N-), emit bright fluorescence under UV light and are characterized by high fluorescence quantum yield, good photostability, chemical stability, and low toxicity [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Rare earth organic fluorescent materials, such as those containing Eu\u003csup\u003e3+\u003c/sup\u003e and Tb\u003csup\u003e3+\u003c/sup\u003e, offer advantages like longer fluorescence lifetimes and narrow emission peaks [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. However, their luminescence is susceptible to quenching due to interference from other groups in the luminescence center, and they are relatively expensive. Liang et al. [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e] encapsulated HMDA[Eu(DBM)\u003csub\u003e4\u003c/sub\u003e] and Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003eS:Eu\u003csup\u003e3+\u003c/sup\u003e fluorescent materials onto the surface of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e particles using solvothermal and hydrothermal methods, respectively. The resulting red fluorescent magnetic composites exhibited saturation magnetization strengths of 51.2 emu/g and 18.9 emu/g, respectively, with good stability and discriminative ability, effectively performing MPI on ferromagnetic materials. De Melo et al. [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] synthesized a composite of fluorescent cadmium telluride quantum dots and functionalized maghemite nanoparticles (MghNPs@QDs) through electrostatic adsorption using cetyltrimethylammonium bromide as a linker, demonstrating excellent performance in non-destructive MPI. A significant challenge in synthesizing magnetic fluorescent composites is ensuring that the fluorescent material is securely encapsulated on the surface of the magnetic particles. The fluorescent material should remain firmly attached to the particles to guarantee effective MPI [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn this paper, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY magnetic luminescent particles were synthesized by coating LY organic fluorescent pigments onto the surface of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e hollow nanospheres using epoxy resin. The Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e hollow nanospheres were synthesized via the solvothermal method. The structure, microscopic morphology, luminescence, and magnetic properties of the Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY composite were characterized. Additionally, MPI of the workpiece was conducted using the composite.\u003c/p\u003e"},{"header":"2. Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1. Materials\u003c/h2\u003e \u003cp\u003eFerric chloride hexahydrate (FeCl\u003csub\u003e3\u003c/sub\u003e\u0026middot;6H\u003csub\u003e2\u003c/sub\u003eO, 99%), sodium acetate anhydrous (CH\u003csub\u003e3\u003c/sub\u003eCOONa, 99%), ethylene glycol ((CH\u003csub\u003e2\u003c/sub\u003eOH)\u003csub\u003e2\u003c/sub\u003e, 98%), E51 epoxy resin (E51), lemon yellow (C\u003csub\u003e16\u003c/sub\u003eH\u003csub\u003e9\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003eO\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e2\u003c/sub\u003eNa\u003csub\u003e3\u003c/sub\u003e, LY, 99%), and sodium dodecylbenzene sulfonate (C\u003csub\u003e12\u003c/sub\u003eH\u003csub\u003e25\u003c/sub\u003eSO\u003csub\u003e3\u003c/sub\u003eNa, 98%) were purchased from Shanghai Macklin Biochemical Technology Co. Ltd. All reagents were used without further purification.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2. Synthesis of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanospheres\u003c/h2\u003e \u003cp\u003eFeCl\u003csub\u003e3\u003c/sub\u003e\u0026middot;6H\u003csub\u003e2\u003c/sub\u003eO, C\u003csub\u003e12\u003c/sub\u003eH\u003csub\u003e25\u003c/sub\u003eSO\u003csub\u003e3\u003c/sub\u003eNa, CH\u003csub\u003e3\u003c/sub\u003eCOONa, and (CH\u003csub\u003e2\u003c/sub\u003eOH)\u003csub\u003e2\u003c/sub\u003e were sequentially added to the reactor in a molar ratio of 1:0.003:3:91.98 and thoroughly dispersed. The prepared solution was sealed in a muffle furnace and allowed to react slowly at 200 ℃ for 15 hours. After the reaction, the precipitate was washed with deionized water to obtain the magnetic nanospheres.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3. Synthesis of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY composite\u003c/h2\u003e \u003cp\u003e0.5 g of magnetic nanospheres, 0.5 g of LY were thoroughly mixed with 1 mL of E51 epoxy resin emulsion. Then, 0.2 mL of hardener was added, stirred well, and left to cure for 8 hours. The resulting block material was placed in a 30 mL ball mill jar with ceramic balls and ground using a ball mill. The magnetic fluorescent composite was obtained by washing the powder with deionized water after ball milling.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4. Characterization\u003c/h2\u003e \u003cp\u003eThe microscopic morphology of the magnetic nanospheres, fluorescent materials, and magnetic fluorescent composite was observed using scanning electron microscope (SEM, Zeiss Gemini-300). The material structures and molecular groups of the samples were analyzed using an X-ray diffractometer (XRD, Rigaku D/MAX) and a Nicolet iS20 Fourier transform infrared spectrometer (FTIR), respectively. The photoluminescence spectra, decay curves, and variable temperature fluorescence curves of the samples were measured using an Edinburgh steady-state and transient fluorescence spectrometer. The magnetic properties of the samples were characterized using a MicroSense EZ9 sample vibration magnetometer. The microscopic morphology of the magnetic particles moving under a magnetic field was observed using an Olympus GX41 optical microscope.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results and Discussion","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e3.1. Morphological and structural characterization of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY composite\u003c/h2\u003e \u003cp\u003eThe material structure of the sample can be inferred from the XRD data results. In the XRD pattern of Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea, the X-ray powder diffraction patterns of E51 and LY show a broad diffuse scattering peak near 20\u0026deg; and no peaks indicative of crystalline phases, indicating that the material exists in an amorphous form. The diffraction pattern of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e hollow nanospheres has eight narrow peaks at 18.46\u0026deg;, 30.28\u0026deg;, 35.57\u0026deg;, 37.2\u0026deg;, 43.21\u0026deg;, 53.55\u0026deg;, 57.15\u0026deg;, and 62.68\u0026deg;, corresponding to (111), (220), (311), (222), (400), (422), (511), and (440) of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e (JCPDS No. 19\u0026ndash;0629) [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. The diffraction peaks of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY composite are similar to those of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanospheres, except that these peaks are slightly weaker.\u003c/p\u003e \u003cp\u003eFTIR analyses were conducted to confirm the coating of the magnetic particles with fluorescent material using resin. In the spectra of E51 and LY shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb, the peaks at 2932 and 2860 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e can be attributed to the bending vibration of -CH. The peaks at 1600, 1535, and 1480 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e correspond to the stretching vibration of the benzene ring in the E51 and LY molecules. In the spectrum of E51, the characteristic peak of the epoxy group appears at 913 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. The characteristic absorption peak at 1070 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is attributed to the stretching vibration of -SO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e in the LY molecule. The Fe-O group in Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e is located at 575 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. All these characteristic peaks are present in the spectral curves of the Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY composite.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe SEM image of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e particles synthesized by the solvothermal method shows that their morphology consists essentially of hollow spheres with a particle size of approximately 450 nm, as depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb and \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec show the microscopic morphology of the LY pigments and E51 resin, respectively. Combined with XRD analysis, it is evident that both LY and E51 resin are in amorphous form. The Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY composite was obtained by coating the surface of the nanospheres with the fluorescent pigment LY using resin. The particles were mixed and bound together by the resin with the fluorescent pigment, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed. Elemental analysis of the microscopic surface of the material was performed using EDS-mapping. The distribution of the elements N, C, S, Na, O, and Fe in the composite is shown in Figs.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ef-\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ek, along with the mass percentage of these elements (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003el).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanospheres can be prepared by heating the reaction solution in a Teflon reactor at high temperature by the solvothermal method. According to the Ostwald ripening mechanism, at high temperature and pressure, the tiny particles inside the nanospheres dissolve, while Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e particles generated in the solution accumulate on the outer surface of the nanospheres. Due to the difference in surface energy between the inside and outside of the nanospheres, hollow nanospheres are gradually formed [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. The E51 epoxy resin molecules contain various polar groups and reactive epoxy groups, which exhibit strong adsorption effects on the oxygen atoms on the surface of the nanospheres and on groups such as C\u0026thinsp;=\u0026thinsp;O and -SO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e in the LY fluorescent pigment molecules. The resin and amine curing agent undergo a crosslinking polymerization reaction to form Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY composite blocks. After ball milling and crushing the blocks, most of the LY fluorescent pigments remain stably encapsulated on the surface of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanospheres due to the resin\u0026rsquo;s adsorption. The encapsulation scheme is illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Luminescence properties of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY composite\u003c/h2\u003e \u003cp\u003eThe results measured by fluorescence spectrometer, shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, reveal the luminescence properties of LY fluorescent pigments and the Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY composite. The LY fluorescent pigment exhibits a broad absorption peak between 325\u0026ndash;500 nm (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea). Under an excitation wavelength of 430 nm, LY emits a strong yellow-green fluorescence with a primary peak wavelength of 525 nm. The emission spectra of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY show a blue shift compared to that of LY, which is hypothesized to be caused by electrostatic interaction between the LY fluorescent pigment molecules and the E51 resin molecules. In the LY molecule, two benzene rings are linked by an azo bond -N\u0026thinsp;=\u0026thinsp;N- to form a conjugated structure, and the molecule contains numerous conjugated double bonds, allowing LY to effectively absorb photons and emit fluorescence [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe comparison of the luminescence of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY under visible and UV light is shown in the inset of Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb. The fluorescence intensity and fluorescence lifetime of the Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY composite are reduced due to the quenching effect of the black Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e powder [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. The decay curve data of the samples in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec were fitted with a biexponential decay function, yielding average fluorescence lifetimes of 4.25 ns for LY and 3.10 ns for Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. The fluorescence spectra of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY were further tested at different temperatures with an excitation wavelength of 430 nm, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ed. The intensity of the primary peak in the emission spectra gradually decreased when heated from room temperature to 150 ℃, indicating temperature-induced quenching of the luminescence. Despite the reduction, the material still exhibits significant fluorescence intensity at 150 ℃, demonstrating its suitability for use in complex temperature environments.\u003c/p\u003e \u003cp\u003eThe phenomenon of luminescence observed in fluorescent materials is due to the transitions of electrons between different orbitals within their molecules. This results in a difference between the wavelengths of the excitation and emission peaks, known as the Stokes shift (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea) [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eb shows the Jablonski energy level diagram of photoluminescence [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Upon absorption of UV light with an energy of \u003cem\u003ehν\u003c/em\u003e\u003csub\u003eA\u003c/sub\u003e, the electrons in the molecule transfer from the ground state energy level (S\u003csub\u003e0\u003c/sub\u003e) to the unstable excited states (S\u003csub\u003e1\u003c/sub\u003e or S\u003csub\u003e2\u003c/sub\u003e). Being in an unstable state, the electrons will return to the stable ground state. During the internal energy transfer process, the electrons transfer back to S\u003csub\u003e1\u003c/sub\u003e by vibrational relaxation or radiative relaxation after absorbing light energy. From the S\u003csub\u003e1\u003c/sub\u003e energy level, a non-radiative transition or emission of light with an energy of \u003cem\u003ehν\u003c/em\u003e\u003csub\u003eF\u003c/sub\u003e occurs, which is called fluorescence. Another form of electron transition is intersystem crossing, where the transition from the triplet state to the ground state is accompanied by a non-radiative transition or emission of light with an energy of \u003cem\u003ehν\u003c/em\u003e\u003csub\u003eP\u003c/sub\u003e, known as phosphorescence. The luminescence of the fluorescent pigment LY is classified as fluorescence. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ec shows the CIE 1931 colorimetric diagram developed by the Commission Internationale de l'\u0026Eacute;clairage. The curved contour line of the CIE chromaticity diagram represents the trajectory of all visible wavelengths [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. The number along the line indicates the dominant wavelength of visible light. The color coordinates of the LY fluorescent pigment and the Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY composite are (\u003cem\u003ex\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.25, \u003cem\u003ey\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.72) and (\u003cem\u003ex\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.19, \u003cem\u003ey\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.76), respectively.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Magnetic properties of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY\u003c/h2\u003e \u003cp\u003eThe magnetic properties of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e magnetic nanospheres and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY magnetic luminescent composite were investigated using a VSM. The measured hysteresis loops are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ea. The Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e hollow nanospheres demonstrated good paramagnetic properties and high saturation magnetization strength, with saturation magnetization values of 85.54 emu/g for Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e and 53.22 emu/g for Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY. The remanence of the two was measured to be 8.64 emu/g and 2.16 emu/g, respectively, under a magnetic field of \u0026plusmn;\u0026thinsp;2 T, and the coercivities were 77.55 Oe and 23.02 Oe, respectively. The magnetic suspension of the Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY magnetic luminescent composite under UV light is shown in the inset. The magnetic luminescent particles in the suspension are attracted to the inner wall of the cuvette by a magnet, emitting a bright yellow-green color.\u003c/p\u003e \u003cp\u003eTo gain a clearer understanding of the magnetic response properties of the Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY magnetic luminescent composite, optical microscopy coupled with a double-pole electromagnet was used to observe the motion of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY particles under a uniform magnetic field. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eb and \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ec, the Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY particles are randomly distributed when the external magnetic field strength is zero, appearing yellow-green under UV light irradiation. When an external magnetic field is applied, the particles exhibit mutual attraction, agglomerating to form short chains. The direction of the chain length of the magnetic agglomerates aligns with the direction of the external magnetic field. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ed and \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ee, when the uniform magnetic field strength is increased to 0.2 T, several short magnetic chains rapidly assemble to form a thick, long magnetic chain parallel to the magnetic field direction. Under UV light, a magnetic chain of approximately 500 \u0026micro;m in length with yellow-green fluorescence can be observed.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Magnetic particle inspection\u003c/h2\u003e \u003cp\u003eThe synthesized Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY magnetic luminescent composite needs to be calibrated for concentration and tested for defect detection sensitivity prior to MPI. The well-dispersed Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY magnetic suspension was poured into a centrifuge tube placed in a holder and left undisturbed for 1 hour in the absence of a magnetic field to allow the particles in the magnetic suspension to precipitate. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ea, the precipitated volume at the bottom of the centrifuge tube gradually increases. When the volume of precipitation is less than 0.1 mL, a certain amount of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY powder must be replenished to maintain the suspension\u0026rsquo;s effectiveness for MPI. This method is used to calibrate the concentration of the magnetic suspension after it has been used for flaw detection [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe sensitivity of the Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY fluorescent magnetic composite was tested using a test piece shim, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eb. A 30 \u0026micro;m deep artificial defect was engraved on the surface of the test piece, which was then placed face down on an iron block. The calibrated magnetic suspension was sprayed on the back surface of the test piece while an alternating magnetic field was applied to the iron block for magnetization [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Due to magnetic flux leakage at the defects, the magnetic field intensity is higher at the defect edges. Under the magnetic field, the Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY particles rapidly formed a yellow-green pattern on the back side of the test piece, indicating that the Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY composite possesses good discrimination and sensitivity, accurately revealing the location of the defects.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAdditionally, MPI experiments were conducted on a gear workpiece using the Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY composite. The test bench model is illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ea. The experiments employed a method combining axial and circumferential magnetic fields. A current passed through the iron core connecting the electrodes on both sides, creating a circumferential magnetic field around it. This setup could detect axial surface defects on a rotary workpiece. Meanwhile, the ring solenoid generated a magnetic field parallel to the axial direction, allowing for the detection of surface defects perpendicular to the axial direction. A simple MPI test bench was constructed based on this model (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003eb). The axial and circumferential magnetic fields were controlled by two AC power supplies on the left and right, respectively.\u003c/p\u003e \u003cp\u003eThe steps of MPI included: preparation of the magnetic suspension, surface pretreatment of the workpiece, magnetization of the workpiece, spraying of the magnetic suspension, defect observation, demagnetization of the workpiece, and post-processing of the workpiece. Under UV light, yellow-green magnetic particle indications on the workpiece surface revealed surface defects. A camera was used to capture images of these defects for further analysis. As shown in Figs.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ec-\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ef, cracks between the tooth roots of the cast iron gear were clearly observed. These cracks, viewed under a fluorescence microscope, showed Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY magnetic luminescent particles accumulating in the cracks due to magnetic flux leakage. The average width of the cracks between the tooth roots was about 50 \u0026micro;m. The Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY magnetic luminescent composite effectively and accurately detected the defects on the gear surface.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"4. Conclusions","content":"\u003cp\u003eIn conclusion, the Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY magnetic fluorescent composite was synthesized using a resin-binding method, achieving a saturation magnetization strength of 53.22 emu/g and exhibiting good paramagnetic properties. The material\u0026rsquo;s excitation and emission wavelengths are 430 nm and 525 nm, respectively, with a fluorescence lifetime of 3.1 ns. The epoxy groups on the resin molecules effectively adsorb the azo fluorescent pigment molecules onto the surface of the nanospheres, preventing detachment. Under UV light, the Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY composite demonstrates high discrimination and sensitivity, making it suitable for applications in MPI.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003cstrong\u003eCompeting interest\u003c/strong\u003e \u003cp\u003eThe authors declare that they have no conflict of interest.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThis work was supported by Fundamental Research Funds for the Central Universities (2024JBZY027) and the National Natural Science Foundation of China (No. 51927810).\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eZhiqi Liang drew all the figures and wrote the main manuscript. Zhili Zhang and Decai Li supervised and revised the paper. All authors reviewed the manuscript.\u003c/p\u003e\u003ch2\u003eData availability\u003c/h2\u003e \u003cp\u003eThe datasets generated during and/or analyzed during the current study are available from the corresponding authors on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eWu, Q., Dong, K., Qin, X., et al.: Magnetic particle inspection: Status, advances, and challenges-demands for automatic non-destructive testing[J], p. 103030. NDT \u0026amp; E International (2023)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGupta, M., Khan, M.A., Butola, R., et al.: Advances in applications of Non-Destructive Testing (NDT): A review[J]. Adv. Mater. Process. Technol. \u003cb\u003e8\u003c/b\u003e(2), 2286\u0026ndash;2307 (2022)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDu, W., Zhao, Y., Roy, R., et al.: A review of miniaturised Non-Destructive Testing technologies for in-situ inspections[J]. 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Sensors. \u003cb\u003e20\u003c/b\u003e(16), 4582 (2020)\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-nondestructive-evaluation","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jone","sideBox":"Learn more about [Journal of Nondestructive Evaluation](http://link.springer.com/journal/10921)","snPcode":"10921","submissionUrl":"https://submission.nature.com/new-submission/10921/3","title":"Journal of Nondestructive Evaluation","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Nanospheres, Fe3O4, Luminescence, Magnetic, Magnetic particle inspection","lastPublishedDoi":"10.21203/rs.3.rs-4864962/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4864962/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eMagnetic particle inspection, a widely used nondestructive testing method, is employed to detect surface defects in ferromagnetic materials due to its ease of operation, low cost, and high efficiency. In this study, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e hollow nanospheres were synthesized by a solvothermal method. Lemon yellow (LY) pigments were successfully encapsulated on the surface of these magnetic nanospheres using E51 epoxy resin. The synthesized Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/E51/LY composite material was characterized in terms of its microscopic morphology, physical phase, and structural properties. The adsorption mechanism of the fluorescent materials on the particle surface was analyzed. Additionally, the photoluminescence and magnetic properties of the composite were tested and evaluated. A magnetic particle inspection test bench was then established to detect defects in the workpiece. The composite exhibited a saturation magnetization of 53.22 emu/g and emitted yellow-green fluorescence at 525 nm under ultraviolet light. The surface defects of the workpiece were accurately detected using magnetic fluorescent particles.\u003c/p\u003e","manuscriptTitle":"Synthesis of Fe3O4 encapsulated with lemon yellow for application in magnetic particle inspection","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-09-03 18:59:18","doi":"10.21203/rs.3.rs-4864962/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-01-01T12:10:18+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-01-01T12:05:31+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"292499473789899167461428130832624493091","date":"2025-01-01T12:02:21+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-11-07T15:45:43+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"121967597009836228537893635871426521135","date":"2024-10-18T18:14:17+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-10-18T16:45:35+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-09-23T18:53:38+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-08-08T02:50:27+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Nondestructive Evaluation","date":"2024-08-06T02:30:59+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-nondestructive-evaluation","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jone","sideBox":"Learn more about [Journal of Nondestructive Evaluation](http://link.springer.com/journal/10921)","snPcode":"10921","submissionUrl":"https://submission.nature.com/new-submission/10921/3","title":"Journal of Nondestructive Evaluation","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"a5198d20-973a-4222-a4d5-416e5836accc","owner":[],"postedDate":"September 3rd, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-03-17T16:02:23+00:00","versionOfRecord":{"articleIdentity":"rs-4864962","link":"https://doi.org/10.1007/s10921-025-01175-z","journal":{"identity":"journal-of-nondestructive-evaluation","isVorOnly":false,"title":"Journal of Nondestructive Evaluation"},"publishedOn":"2025-03-10 15:57:47","publishedOnDateReadable":"March 10th, 2025"},"versionCreatedAt":"2024-09-03 18:59:18","video":"","vorDoi":"10.1007/s10921-025-01175-z","vorDoiUrl":"https://doi.org/10.1007/s10921-025-01175-z","workflowStages":[]},"version":"v1","identity":"rs-4864962","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4864962","identity":"rs-4864962","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}