Different alkali carbonates on the microstructure and photoluminescence properties of SrWO 4 :Tb 3+ phosphors

Different alkali carbonates on the microstructure and photoluminescence properties of SrWO 4 :Tb 3+ phosphors | 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 Article Different alkali carbonates on the microstructure and photoluminescence properties of SrWO 4 :Tb 3+ phosphors Xiaoxing Ma, Faxue Ma, Dingcheng Yang, Xueqing Zhu, Aiyun Jiang This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8884256/v1 This work is licensed under a CC BY 4.0 License Status: Under Revision Version 1 posted 16 You are reading this latest preprint version Abstract In this research terbium-doped strontium tungsten oxide samples were synthesized using solid-state synthesis method. It was found through X-Ray powder diffraction (XRD) that the samples belong to the tetragonal crystal system and have the space group I4 1 /a. The scanning electron microscope (SEM) images indicate that the Na, K, W and Tb atoms are uniformly distributed throughout the samples. Photoluminescence (PL) measurements were applied for sample characterization. All of them exhibited green emission with highest peak at 545 nm attributable to 5 D 4 → 7 F 5 transition. The highest emission intensity was observed in SrWO 4 :0.4%Tb sample while higher doping levels resulted in decrease of the PL intensities due to concentration quenching. Samples with additional alkali metal ions for charge compensation were also prepared and their PL properties were measured. Doping with 0.5 mol% K + ions yielded a 1.8-fold increase in mechanical strength, a 4.4-fold enhancement in operational lifespan, and a 153% improvement in quantum yield. These results indicate that SrWO 4 :0.4%Tb,0.5%K materials have great potential application as green phosphors in LEDs. Physical sciences/Chemistry Physical sciences/Materials science Physical sciences/Nanoscience and technology Physical sciences/Physics Lanthanides Phosphors Strontium Tungsten Oxide Luminescence Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Lanthanides (RE 3+ ), including Tb, Eu, and Dy, exhibit efficient luminescence due to shielded 4f electrons [ 1 ] , creating discrete energy levels.Their sharp emissions stem from electric-dipole-forbidden 4f–4f transitions; direct excitation yields low efficiency, while indirect excitation via parity-mixing with the host lattice enhances it [ 2 ] .Transition probabilities are sensitive to the local ionic environment [ 3 ] . is prominent in optoelectronics for its strong green emission at 543 nm corresponds to 5 D 4 → 7 F 5 transitions, alongside peaks at 488, 586, 621 and 650 nm corresponds to 5 D 4 → 7 F 6 , 5 D 4 → 7 F 4 , 5 D 4 → 7 F 3 and 5 D 4 → 7 F 2 transitions respectively [ 2 ] . Phosphors that emit white light are imperative materials, which have been broadly applied in solid state lighting. The white light is a blended light of multi-color and perceived by human eyes as white light. There are two common approaches to white light generation: (i) blending three monochromatic sources (red, green and blue), or (ii) utilizing phosphors to convert UV or blue light into a mix of red, green and blue; or yellow and blue. In contrast, single-matrix phosphors can emit blue, green, and red lights that are potential white light sources because they offer greater luminescence efficiency and lower manufacturing costs compared to systems requiring multiple phosphors to accomplish the same effect. Therefore, it is an urgent task to develop single-component (single-phase) phosphor that can produce white-light emission. Strontium Tungsten Oxide (SrWO 4 ) has received a great deal of attention over the past century because of its intriguing luminescence and structural characteristics. SrWO 4 , characterized by its Sr 2+ ions and WO 4 2− groups with coordination numbers of eight and four, respectively, is a useful material that exhibits sky-blue photoluminescence under shortwave ultraviolet light and has been reported for applications in LED, photocatalysis, and laser technology. Here, SrWO 4 :xTb, yA (where x = 0.1% mol, 0.4% mol, 0.7% mol, 1% mol, 3% mol, 5% mol, 7% mol, 10% mol; A = Li, Na, K; y = 0, 0.5% mol, 1% mol, 3% mol) were prepared by a solid-state reaction method. The effects of the initial reactant content on the phase compositions, morphologies, and luminescence properties of these samples were investigated. The co-doping of A + by charge compensator is expected to significantly improve the luminescence properties of SrWO 4 :xTb. Experimental Synthesis Phosphors of general formula, SrWO 4 :xTb, yA were synthesized by solid-state reaction method. Stoichiometric amounts of analytical grade starting materials (SrWO 4 , Tb 4 O 7 , Li 2 CO 3 , Na 2 CO 3 , K 2 CO 3 ) were mixed and ground in agate mortar. The mixtures were transferred to a crucible and sintered at 950 ℃ for 8 h. The obtained products were re-grounded in agate mortar and used for further analysis. Structural properties of SrWO 4 :xTb, yA samples were studied from XRD (BRUKER D8 ADVANCE diffractometer) patterns recorded using CuKα1 radiation ( λ = 1.5406 Å) in the diffraction limit 10–70° with a scan speed of 0.02°/min in Bragg Brentano geometry. Surface features of the samples were studied using field emission scanning electron microscope (Nova Nano SEM-450, equipped with XFlash detector 6/10-Bruker). Compositional analysis was done using EDS measurement (EDS Quantax 200, Germany). The excitation and emission spectra of the samples were measured using Edinburgh FLS980 spectrofluorometer equipped with a continuous xenon lamp of 450 W for steady state, a pulsed xenon lamp for decay measurements and RED photo multiplier tube to detect the luminescence. Result and discussion XRD is a very powerful characterization technique used to identify the crystal structure of synthesized materials. Figure 1 a depicts the XRD patterns of undoped and Tb 3+ -doped SrWO 4 phosphors. The XRD patterns of all the studied compositions were closely identical, suggesting that all the phosphors under investigation crystallized to tetragonal crystal structure. The position and relative intensity of all diffraction peaks are in good agreement with the standard values for bulk tetragonal SrWO 4 (JCPDS 08-0490). No appreciable change in the diffraction patterns of SrWO 4 with Tb 3+ ion substitution was observed, indicating that the Tb 3+ was successfully doped into the host matrix without affecting the parent crystal structure. By considering the ionic radius balance, Tb 3+ (0.923 Å, CN = 6) ions are most likely to replace the Sr 2+ (1.00 Å, CN = 6) site in the host matrix. The Rietveld analysis was performed on SrWO 4 :0.4%Tb as well as SrWO 4 :0.4%Tb, 0.5%K samples (Fig. 2 (b) and (d)) using the Fullprof package and assuming a I4 1 /a space group for a scheelite type tetragonal structure. The values of R wp and R p are 8.26% and 6.11% of SrWO 4 :0.4%Tb and 9.34% and 6.34% of SrWO 4 :0.4%Tb, 0.5%K, respectively. The Rietveld analysis shows that the samples are in crystalline phase, and no phase mixture was observed which confirms the results obtained by conventional XRD. The crystallographic data for both materials are presented in Table S1 . As shown in Fig. 2 c, the PXRD patterns of SrWO 4 :0.4%Tb samples remained unchanged after doping with Li, Na, K, demonstrating no phase transition under those reaction conditions. The morphology of SrWO 4 :0.4%Tb, SrWO 4 :0.4%Tb, 0.5%Na and SrWO 4 :0.4%Tb, 0.5%K was studied using SEM. Figure 2 shows that the morphology of particles has no fixed geometry. The size of sample SrWO 4 :0.4%Tb (Fig. 2 a) is about 20×15 µm, which is significantly larger than the samples doped with alkaline metal elements. With dimensions of 10×8 µm and 8×5 µm for SrWO 4 :0.4%Tb, 0.5%Li (Fig. 2 b) and SrWO 4 :0.4%Tb, 0.5%K (Fig. 2 f) respectively, SrWO 4 :0.4%Tb, 0.5%Na (Fig. 2 c) possesses a significantly reduced size, 4×2 µm, making it the most diminutive component. The variation in alkali metal identity is the primary driver of the observed size differences, with its effect overshadowing the more subtle variations induced by changes in Na doping concentration within any given alkali metal system. Moreover, sample SrWO 4 :0.4%Tb is smoother and has no fine grains adhering to its surface. This phenomenon is attributed to the fluxing action of the alkali metal carbonates [ 4 ] . Their role as efficient solubilizers enhances precursor dissolution and mass transport, which accelerates the reaction rate and favors the formation of smaller particles. The micro-scope size of the prepared phosphor makes it a potential phosphor candidate as per the point of view of WLED. The similarity between the sizes derived from XRD and SEM suggests that the particles are well crystalline. EDS elemental mapping (Figure S3) showed that both Sr, Tb, Na and K were uniformly dispersed throughout the corresponding crystals and no other impurities were observed. This indicates that the Tb atoms are atomically dispersed within the compound. To investigate the luminescence properties of Tb 3+ doped SrWO 4 phosphor, a series of samples were prepared. Figure 3 a is the excitation spectrum of the SrWO 4 sample at room temperature with the monitoring wavelength at 435 nm, and the scanning range is 300–400 nm. The excitation band of WO 4 2− is observed at 320–390 nm, resulting from the 1 A 1 → 1 T 2 energy transition [ 5 ] , which coincides with the absorption spectrum due to the internal electronic transition in WO 4 2− . Figure 3 b is the emission spectrum of the SrWO 4 phosphor excited at 275 nm. The scanning area is 300–700 nm. As shown in the figure, four characteristic peaks located at 411 nm, 438 nm, 468 nm and 477 nm can be observed within the broad absorption band spanning 330–600 nm, which are attributed to the ³T₂→¹A₁ electron transition of the WO₄²⁻ ion [ 5 ] . In Fig. 3 c, the excitation spectrum of SrWO 4 :0.4%Tb phosphor monitored at 545 nm has a scanning range of 300–520 nm. The presence of the strong band at 303 nm of the WO 4 2− group in the excitation spectrum of Tb 3+ ions means that there is an energy transfer from the O 2− to W 6+ and the one from O 2− to Tb 3+ . In the region of 300–500 nm, there are some peaks ascribed to the f–f transitions of Tb 3+ , which are assigned to the electron transition from the 7 F 6 ground state to the different excitation states as 303 nm 5 H 4 , 319 nm 5 H 7 , 340 nm 5 G 2 , 352 nm 5 D 2 , 360 nm 5 G 5 , 369 nm 5 G 6 , 379 nm 5 D 3 and 488 nm 5 D 4 [ 6 ] . According to the results obtained from the excitation spectrum, 369 nm is chosen as the host sensitization wavelength for the evaluation of the photoluminescence emission characteristics of the SrWO 4 :0.4%Tb 3+ samples. Figure 3 d depicts the emission spectra which consists of four well-defined emission peaks at 489 nm (blue, 5 D 4 → 7 F 6 ), 545 nm (green, 5 D4→ 7 F 5 ), 587 nm (yellow, 5 D 4 → 7 F 4 ), and 621 nm (red, 5 D 4 → 7 F 3 ) due to the distinct intra-configurational 4 f 8 - 4 f 8 transitions of Tb 3+ ions in the host [ 2 , 6 ] . Among these peaks, the green emission corresponds to the 5 D 4 → 7 F 5 induced electric dipole transition. This transition is a magnetic dipole transition, following the selection rule Δ J = ± 1 and is not dependent on crystal environment [ 7 ] . The 438 nm emission peak has been attributed to 5 D 3 – 7 F 4 of Tb 3+ ions in several studies [ 8 , 9 ] ; however, drawing on the majority of literature [ 10 , 11 ] and the unique emission signature of WO 4 2− ( Fig. 3 b and Figure S3), we interpret this peak as originating from WO 4 2− rather than Tb 3+[ 12 , 13 ] . Hence the synthesized Tb 3+ doped SrWO 4 samples can be used as a potential candidate for WLED application as a green source [ 14 ] . Here, the energy transfer from WO 4 2− to Tb 3+ is highly efficient and proceeds via three primary mechanisms [ 15 ] . The distinct emission spectrum arises from a sequential three-step process: initially, WO 4 2− absorbs ultraviolet light; subsequently, the absorbed energy is transferred to Tb 3+ ions; and finally, this energy induces the de-excitation of Tb 3+ ions. Furthermore, a strong and broad excitation band in the ultraviolet region, combined with the characteristic emission of Tb 3+ , enhances the effective excitation of terbium through the sensitizer. From the emission spectra (Figure S4), it is evident that the emission intensity increases as the Tb 3+ concentration rises from 0.1% to 0.4%, then decreases from 0.7% up to 10% doping. This decline in intensity is attributed to concentration quenching [ 10 ] , which becomes significant at higher doping levels. Consequently, PL excitation and emission studies indicate that 0.4% represents the optimal doping concentration for the SrWO₄:x% Tb 3+ phosphor. When trivalent Tb 3+ ions replace divalent Sr 2+ ions in the main lattice, it leads to a charge imbalance. The defects or trap states caused by charge imbalance suppress luminescence efficiency, thereby reducing luminescence intensity [ 16 , 17 ] . To address this issue, we introduced alkali metal ions (Li + , Na + and K + ) as charge compensators. By co-doping alkali metal ions, we effectively neutralized the charge imbalance, thereby stabilizing the crystal structure and changing luminescence intensity. There are no differences in the shape and location of the peaks in the emission spectra between SrWO 4 :0.4%Tb 3+ and SrWO 4 :0.4%Tb, 0.5%K. Interestingly, not all alkali metals systematically enhance [ 18 – 20 ] or quench [ 4 ] the luminescence. The emission intensity is dependent on both the identity of the alkali metal and the molar ratio of the dopants [ 21 ] . The incorporation of varying amounts of Li (Fig. 4 a) and Na (Fig. 4 b) consistently reduced the fluorescence intensity. In contrast, a potassium concentration of 0.5% mol enhanced the fluorescence emission intensity, producing a 1.83-fold increase (Fig. 4 c and 4 d). At higher concentrations (1% mol and 3% mol), however, the fluorescence intensity decreased (Fig. 4 c). Additionally, under a 0.5 mol% doping level, a clear trend is observed: a larger alkali ion radius (K⁺ > Na⁺ > Li⁺) corresponds to a higher Tb³⁺ PL intensity, suggesting a role for charge compensation effects (Fig. 4 d). Enhanced luminescence can be attributed to the following mechanisms [ 21 ] . Firstly, charge compensation is achieved through the co-doping mechanism described by the substitution Tb 3 ⁺ + K⁺ → 2Sr 2+ , which directly contributes to an increase in the emission intensity. Secondly, the incorporation of K⁺ ions help suppress the formation of vacancy defects that typically result from the substitution of Tb 3 ⁺ for Sr 2+ . Thirdly, doping with K⁺ ions induce a lattice expansion, as evidenced by an increased unit cell volume and interionic spacing. This structural effect reduces non‑radiative relaxation pathways for the Tb³⁺ ions, thereby further enhancing the overall luminous efficiency. Based on established literature [ 21 , 22 ] , the doping of alkali metal ions introduces oxygen vacancies into the host lattice. Due to strong hybridization of charge-transfer states, these vacancies act as efficient sensitizers, promoting energy transfer and thereby significantly enhancing the 4f–4f transition efficiency of Tb 3+ . This supports that larger ionic radii facilitate the formation of continuous energy-transfer pathways. The luminescence decay observed in the Li⁺ and Na + -doped system, however, may be attributed to the small ionic radius of Li⁺ and Na + , which allows a portion of Li⁺ and Na + ions to occupy interstitial lattice sites. Such off-site occupancy induces localized lattice distortion and stress, which hinders effective energy transfer and enhances non-radiative relaxation of Tb³⁺ ions, ultimately leading to a decrease in luminescence intensity. The average lifetimes of SrWO 4 :0.4%Tb, 0.5%A (A = Li, Na, K) and SrWO 4 :0.4%Tb phosphors at 545 nm are calculated to be 1.28 ms (Li), 1.31 ms (Na), 10.26 ms (K) and 2.33 ms, respectively (Fig. 2 e, Table 1 ). The change trend of the average lifetime is SrWO 4 :0.4%Tb,0.5%K > SrWO 4 :0.4%Tb > SrWO 4 :0.4%Tb,0.5%Na> SrWO 4 :0.4%Tb,0.5%Li, which is consistent with the emission intensity of the phosphor. This may be because K + can reduce the non-radiative transition of Tb 3+ ions, while the special doping position of Li + and Na + gradually increases the possibility of non-radiative transition. The color changes were further annotated using the Commission Internationale de l'Éclairage (CIE) coordinates as shown in Fig. 4 f, as the position shifted from (0.19, 0.18) of SrWO 4 :0.4%Tb to (0.19, 0.19) of SrWO 4 :0.4%Tb, 0.5% Li (0.21, 0.24) of SrWO 4 :0.4%Tb, 0.5% Na and then to (0.22, 0.36) of SrWO 4 :0.4%Tb, 0.5% K. Finally, quantum efficiencies of the samples were evaluated and listed in Table 1 . Highest efficiency was observed in SrWO 4 :0.4%Tb and SrWO 4 :0.4%Tb, 0.5%A (A = Li, Na, K) sample and all these results agree with emission intensities of the samples (Fig. 4 d). As summarized in Table 1 , K⁺ doping at 0.5 mol% induces a 4.4-fold enhancement in luminescence lifetime and a 153% increase in photoluminescence quantum yield. Table 1 Luminescence lifetimes and quantum efficiencies of SrWO 4 :0.4%Tb and SrWO 4 :0.4%Tb, 0.5%A (A = Li, Na, K) samples. Samples Lifetimes Quantum efficiency SrWO 4 :0.4%Tb 2.33 ms 34.90% SrWO 4 :0.4%Tb, 0.5% Li 1.28 ms 28.28% SrWO4:0.4%Tb, 0.5% Na 1.31 ms 31.76% SrWO4:0.4%Tb, 0.5% K 10.28 ms 53.40% Conclusions In summary, SrWO 4 :xTb, yA (where x = 0.1% mol, 0.4% mol, 0.7% mol, 1% mol, 3% mol, 5% mol, 7% mol, 10% mol; A = Li, Na, K; y = 0, 0.5% mol, 1% mol, 3% mol) phosphors were synthesized using the solid state synthesis method and their phase purity was confirmed by X-ray diffraction analysis. The particles synthesized by SEM-EDS analysis were about 2–20 µm in size and possess an irregular morphology. Sr, W, O and Tb were confirmed in the component analysis, and it was found that the doped Tb was evenly distributed by mapping. Examination of the luminescent properties of terbium-doped samples showed expected excitation and emission spectrum with highest emission peak at 544 nm attributable to 5 D 4 → 7 F 5 transition. Comparison of emission intensities revealed that most intensive luminescence was observed in SrWO 4 :0.4%Tb sample. Charge compensation is achieved through the introduction of Group IA ions (Li⁺, Na⁺, or K⁺), which generally results in a slight reduction in emission intensity. Doping with 0.5 mol% K + ions yielded a 1.8-fold increase in mechanical strength, a 4.4-fold enhancement in operational lifespan, and a 153% improvement in quantum yield. The luminescence color of SrWO 4 :0.4%Tb and SrWO 4 :0.4%Tb,0.5%K powders locate at green region in CIE chromatic diagram, so these experimental results imply a potential application of green-emitting optical devices based on SrWO 4 phosphors. Declarations Competing interests The authors declare that they have no competing interests. Author Contribution The research contributions are as follows: Xiaoxing Ma conducted material synthesis, experimental testing, and manuscript drafting; Ma ( corresponding author) designed the experimental framework and guided thesis composition; Yang performed experimental validation; Zhu ( corresponding author) interpreted experimental outcomes and provided analytical instrumentation; Jiang executed language editing for manuscript refinement. Data Availability The data sets used during the current study available from the corresponding author on reasonable request. Funding None. References CUI, R. et al. Luminescent performance of rare earths doped CaBi2Ta2O9 phosphor [J]. J. Rare Earths . 31 (6), 546–550 (2013). WAKEFIELD, G. et al. Structural and optical properties of terbium oxide nanoparticles [J]. J. Phys. Chem. Solids . 60 (4), 503–508 (1999). HILD, F. et al. Structural and Photoluminescence Properties of Evaporated SnO2 Thin Films Doped with Rare Earths [J]. 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Investigation of alkali metals (A + = K, Na, Li) co-doped with samarium ions in the eulytite-type phosphate based phosphors for the enhancement of luminescence properties [J]. J. Lumin. , 219. (2020). LIU, H. et al. K + Co-doped Ca2LaTaO6: RE3+(RE = Pr, Tb) Phosphors: Enhancement photoluminescence intensity and high thermal stability [J]. Ceram. Int. 51 (21), 32701–32710 (2025). LI, Q. et al. Rattling effect mechanism on the temperature stability of low-sintered Ca1–x(Li1/2Eu1/2)xWO4 microwave dielectric ceramics for dielectric resonant antenna applications [J] (Journal of Materiomics, 2025). Additional Declarations No competing interests reported. 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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-8884256","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":597547906,"identity":"24be3ccb-7ea9-4ea3-b650-2c7f05d4b346","order_by":0,"name":"Xiaoxing Ma","email":"","orcid":"","institution":"Huanghe S \u0026 T University","correspondingAuthor":false,"prefix":"","firstName":"Xiaoxing","middleName":"","lastName":"Ma","suffix":""},{"id":597547908,"identity":"dafede59-9e34-4ff9-8683-6e8f0d7616a2","order_by":1,"name":"Faxue Ma","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAApElEQVRIiWNgGAWjYDAC5gMg0oaHn7+BWC1sCSAyTUZyxgHStBy2MWhIIFKHbhuPmdTNtvM8BgwHGD98zCFCi9kxtmTj3LbbPObMDcySM7cRo+V+88HHIC2WDQfYmHmJ0nKMseFwbts5HoMDCURrYQbZcoAkLUC/5JxL5pGccbCZSL8c4zGTzimzs+fnbz744SMxWpAAYwNp6kfBKBgFo2AU4AYATqY0aKRqSQEAAAAASUVORK5CYII=","orcid":"","institution":"Huanghe S \u0026 T University","correspondingAuthor":true,"prefix":"","firstName":"Faxue","middleName":"","lastName":"Ma","suffix":""},{"id":597547910,"identity":"128ed5c1-be91-46b3-a8ef-c77faa3f04ce","order_by":2,"name":"Dingcheng Yang","email":"","orcid":"","institution":"Huanghe S \u0026 T University","correspondingAuthor":false,"prefix":"","firstName":"Dingcheng","middleName":"","lastName":"Yang","suffix":""},{"id":597547911,"identity":"1580009b-4efc-4056-a67f-343ac931880c","order_by":3,"name":"Xueqing Zhu","email":"","orcid":"","institution":"Henan University of Technology","correspondingAuthor":false,"prefix":"","firstName":"Xueqing","middleName":"","lastName":"Zhu","suffix":""},{"id":597547912,"identity":"7a94be93-8e75-4103-a272-e99132c094b4","order_by":4,"name":"Aiyun Jiang","email":"","orcid":"","institution":"Huanghe S \u0026 T University","correspondingAuthor":false,"prefix":"","firstName":"Aiyun","middleName":"","lastName":"Jiang","suffix":""}],"badges":[],"createdAt":"2026-02-15 07:08:15","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8884256/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8884256/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":103733758,"identity":"118a722f-22ef-4e04-904e-ff03882cf2f2","added_by":"auto","created_at":"2026-03-02 09:29:28","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":67281,"visible":true,"origin":"","legend":"\u003cp\u003e(a) X-ray diffraction pattern of SrWO\u003csub\u003e4\u003c/sub\u003e:xTb (x = 0.1%, 0.4%, 0.7%, 1%, 3%, 5%, 7%, 10%) samples; (b)The Rietveld refinement fitted XRD of SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb; (c)X-ray diffraction pattern of SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, yA (A= Li, Na, K; y = 0.5, 1, 3) samples; (d)The Rietveld refinement fitted XRD of SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, 0.5%K.\u003c/p\u003e","description":"","filename":"Onlinefloatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8884256/v1/87fe6669035cb3c1fa26f79b.png"},{"id":103733742,"identity":"d2ef5a66-e4ab-4f0e-8244-e5e5b1102e91","added_by":"auto","created_at":"2026-03-02 09:29:26","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1313931,"visible":true,"origin":"","legend":"\u003cp\u003eSEM of (a) SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb; (b) SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, 0.5%Li; (c) SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, 0.5%Na; (d) SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, 1%Na; (e) SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, 3%Na; (f) SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, 0.5%K\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-8884256/v1/f1534f6899a8374fe91e37c4.png"},{"id":103733682,"identity":"1655f209-4740-47b8-9ed1-c8bad7ea6df7","added_by":"auto","created_at":"2026-03-02 09:29:09","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":52209,"visible":true,"origin":"","legend":"\u003cp\u003e(a) PLE spectra of SrWO\u003csub\u003e4\u003c/sub\u003e; (b) PL spectra of SrWO\u003csub\u003e4\u003c/sub\u003e; (c) PLE spectra of SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb; (d) PL spectra of SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb.\u003c/p\u003e","description":"","filename":"Onlinefloatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-8884256/v1/ac1fe27202f9af7ce055c2d6.png"},{"id":103733741,"identity":"c401db11-9f03-4875-9f7a-c742e966841e","added_by":"auto","created_at":"2026-03-02 09:29:25","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":54254,"visible":true,"origin":"","legend":"\u003cp\u003ePL spectra of SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, yA (A= Li, Na, K; y = 0.5, 1, 3) samples under an excitation wavelength of 545 nm. (a) SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, y Li; (b) SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, y Na; (b) SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, y K; (d) PL spectra of SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb and SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, 0.5%A (A= Li, Na, K); (e) Photoluminescence decay curves for the \u003csup\u003e5\u003c/sup\u003eD\u003csub\u003e4\u003c/sub\u003e level (545 nm). (f) CIE coordinates of the SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb and SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, 0.5%A (A= Li, Na, K) emission.\u003c/p\u003e","description":"","filename":"Onlinefloatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-8884256/v1/c375023d3135bbf5ec0c5054.png"},{"id":104400582,"identity":"99be5a77-5f95-4468-9604-27ad085e9a55","added_by":"auto","created_at":"2026-03-11 12:10:20","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2154300,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8884256/v1/e343f386-4a95-4de5-b68a-58750d8104d1.pdf"},{"id":103733815,"identity":"deb29971-cb66-4376-8053-c3e44799b2d1","added_by":"auto","created_at":"2026-03-02 09:29:42","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":3099481,"visible":true,"origin":"","legend":"","description":"","filename":"SI.docx","url":"https://assets-eu.researchsquare.com/files/rs-8884256/v1/b1d097583233e97098b4bfa1.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Different alkali carbonates on the microstructure and photoluminescence properties of SrWO 4 :Tb 3+ phosphors","fulltext":[{"header":"Introduction","content":"\u003cp\u003eLanthanides (RE\u003csup\u003e3+\u003c/sup\u003e), including Tb, Eu, and Dy, exhibit efficient luminescence due to shielded 4f electrons\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/sup\u003e, creating discrete energy levels.Their sharp emissions stem from electric-dipole-forbidden 4f\u0026ndash;4f transitions; direct excitation yields low efficiency, while indirect excitation via parity-mixing with the host lattice enhances it\u003csup\u003e[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/sup\u003e.Transition probabilities are sensitive to the local ionic environment\u003csup\u003e[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/sup\u003e. is prominent in optoelectronics for its strong green emission at 543 nm corresponds to \u003csup\u003e5\u003c/sup\u003e\u003cem\u003eD\u003c/em\u003e\u003csub\u003e4\u003c/sub\u003e\u0026rarr;\u003csup\u003e7\u003c/sup\u003e\u003cem\u003eF\u003c/em\u003e\u003csub\u003e5\u003c/sub\u003e transitions, alongside peaks at 488, 586, 621 and 650 nm corresponds to \u003csup\u003e5\u003c/sup\u003e\u003cem\u003eD\u003c/em\u003e\u003csub\u003e4\u003c/sub\u003e\u0026rarr;\u003csup\u003e7\u003c/sup\u003e\u003cem\u003eF\u003c/em\u003e\u003csub\u003e6\u003c/sub\u003e, \u003csup\u003e5\u003c/sup\u003e\u003cem\u003eD\u003c/em\u003e\u003csub\u003e4\u003c/sub\u003e\u0026rarr;\u003csup\u003e7\u003c/sup\u003e\u003cem\u003eF\u003c/em\u003e\u003csub\u003e4\u003c/sub\u003e, \u003csup\u003e5\u003c/sup\u003e\u003cem\u003eD\u003c/em\u003e\u003csub\u003e4\u003c/sub\u003e\u0026rarr;\u003csup\u003e7\u003c/sup\u003e\u003cem\u003eF\u003c/em\u003e\u003csub\u003e3\u003c/sub\u003e and \u003csup\u003e5\u003c/sup\u003e\u003cem\u003eD\u003c/em\u003e\u003csub\u003e4\u003c/sub\u003e\u0026rarr;\u003csup\u003e7\u003c/sup\u003e\u003cem\u003eF\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003e transitions respectively\u003csup\u003e[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003ePhosphors that emit white light are imperative materials, which have been broadly applied in solid state lighting. The white light is a blended light of multi-color and perceived by human eyes as white light. There are two common approaches to white light generation: (i) blending three monochromatic sources (red, green and blue), or (ii) utilizing phosphors to convert UV or blue light into a mix of red, green and blue; or yellow and blue. In contrast, single-matrix phosphors can emit blue, green, and red lights that are potential white light sources because they offer greater luminescence efficiency and lower manufacturing costs compared to systems requiring multiple phosphors to accomplish the same effect. Therefore, it is an urgent task to develop single-component (single-phase) phosphor that can produce white-light emission.\u003c/p\u003e \u003cp\u003eStrontium Tungsten Oxide (SrWO\u003csub\u003e4\u003c/sub\u003e) has received a great deal of attention over the past century because of its intriguing luminescence and structural characteristics. SrWO\u003csub\u003e4\u003c/sub\u003e, characterized by its Sr\u003csup\u003e2+\u003c/sup\u003e ions and WO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e groups with coordination numbers of eight and four, respectively, is a useful material that exhibits sky-blue photoluminescence under shortwave ultraviolet light and has been reported for applications in LED, photocatalysis, and laser technology.\u003c/p\u003e \u003cp\u003eHere, SrWO\u003csub\u003e4\u003c/sub\u003e:xTb, yA (where x\u0026thinsp;=\u0026thinsp;0.1% mol, 0.4% mol, 0.7% mol, 1% mol, 3% mol, 5% mol, 7% mol, 10% mol; A\u0026thinsp;=\u0026thinsp;Li, Na, K; y\u0026thinsp;=\u0026thinsp;0, 0.5% mol, 1% mol, 3% mol) were prepared by a solid-state reaction method. The effects of the initial reactant content on the phase compositions, morphologies, and luminescence properties of these samples were investigated. The co-doping of A\u003csup\u003e+\u003c/sup\u003e by charge compensator is expected to significantly improve the luminescence properties of SrWO\u003csub\u003e4\u003c/sub\u003e:xTb.\u003c/p\u003e"},{"header":"Experimental","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eSynthesis\u003c/h2\u003e \u003cp\u003ePhosphors of general formula, SrWO\u003csub\u003e4\u003c/sub\u003e:xTb, yA were synthesized by solid-state reaction method. Stoichiometric amounts of analytical grade starting materials (SrWO\u003csub\u003e4\u003c/sub\u003e, Tb\u003csub\u003e4\u003c/sub\u003eO\u003csub\u003e7\u003c/sub\u003e, Li\u003csub\u003e2\u003c/sub\u003eCO\u003csub\u003e3\u003c/sub\u003e, Na\u003csub\u003e2\u003c/sub\u003eCO\u003csub\u003e3\u003c/sub\u003e, K\u003csub\u003e2\u003c/sub\u003eCO\u003csub\u003e3\u003c/sub\u003e) were mixed and ground in agate mortar. The mixtures were transferred to a crucible and sintered at 950 ℃ for 8 h. The obtained products were re-grounded in agate mortar and used for further analysis.\u003c/p\u003e \u003cp\u003eStructural properties of SrWO\u003csub\u003e4\u003c/sub\u003e:xTb, yA samples were studied from XRD (BRUKER D8 ADVANCE diffractometer) patterns recorded using CuKα1 radiation (\u003cem\u003eλ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1.5406 \u0026Aring;) in the diffraction limit 10\u0026ndash;70\u0026deg; with a scan speed of 0.02\u0026deg;/min in Bragg Brentano geometry. Surface features of the samples were studied using field emission scanning electron microscope (Nova Nano SEM-450, equipped with XFlash detector 6/10-Bruker). Compositional analysis was done using EDS measurement (EDS Quantax 200, Germany). The excitation and emission spectra of the samples were measured using Edinburgh FLS980 spectrofluorometer equipped with a continuous xenon lamp of 450 W for steady state, a pulsed xenon lamp for decay measurements and RED photo multiplier tube to detect the luminescence.\u003c/p\u003e \u003c/div\u003e"},{"header":"Result and discussion","content":"\u003cp\u003eXRD is a very powerful characterization technique used to identify the crystal structure of synthesized materials. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea depicts the XRD patterns of undoped and Tb\u003csup\u003e3+\u003c/sup\u003e-doped SrWO\u003csub\u003e4\u003c/sub\u003e phosphors. The XRD patterns of all the studied compositions were closely identical, suggesting that all the phosphors under investigation crystallized to tetragonal crystal structure. The position and relative intensity of all diffraction peaks are in good agreement with the standard values for bulk tetragonal SrWO\u003csub\u003e4\u003c/sub\u003e (JCPDS 08-0490). No appreciable change in the diffraction patterns of SrWO\u003csub\u003e4\u003c/sub\u003e with Tb\u003csup\u003e3+\u003c/sup\u003e ion substitution was observed, indicating that the Tb\u003csup\u003e3+\u003c/sup\u003e was successfully doped into the host matrix without affecting the parent crystal structure. By considering the ionic radius balance, Tb\u003csup\u003e3+\u003c/sup\u003e (0.923 \u0026Aring;, CN\u0026thinsp;=\u0026thinsp;6) ions are most likely to replace the Sr\u003csup\u003e2+\u003c/sup\u003e (1.00 \u0026Aring;, CN\u0026thinsp;=\u0026thinsp;6) site in the host matrix. The Rietveld analysis was performed on SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb as well as SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, 0.5%K samples (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e(b) and (d)) using the Fullprof package and assuming a I4\u003csub\u003e1\u003c/sub\u003e/a space group for a scheelite type tetragonal structure. The values of R\u003csub\u003ewp\u003c/sub\u003e and R\u003csub\u003ep\u003c/sub\u003e are 8.26% and 6.11% of SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb and 9.34% and 6.34% of SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, 0.5%K, respectively. The Rietveld analysis shows that the samples are in crystalline phase, and no phase mixture was observed which confirms the results obtained by conventional XRD. The crystallographic data for both materials are presented in Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec, the PXRD patterns of SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb samples remained unchanged after doping with Li, Na, K, demonstrating no phase transition under those reaction conditions.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe morphology of SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, 0.5%Na and SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, 0.5%K was studied using SEM. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e shows that the morphology of particles has no fixed geometry. The size of sample SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea) is about 20\u0026times;15 \u0026micro;m, which is significantly larger than the samples doped with alkaline metal elements. With dimensions of 10\u0026times;8 \u0026micro;m and 8\u0026times;5 \u0026micro;m for SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, 0.5%Li (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb) and SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, 0.5%K (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ef) respectively, SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, 0.5%Na (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec) possesses a significantly reduced size, 4\u0026times;2 \u0026micro;m, making it the most diminutive component. The variation in alkali metal identity is the primary driver of the observed size differences, with its effect overshadowing the more subtle variations induced by changes in Na doping concentration within any given alkali metal system. Moreover, sample SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb is smoother and has no fine grains adhering to its surface. This phenomenon is attributed to the fluxing action of the alkali metal carbonates\u003csup\u003e[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003e. Their role as efficient solubilizers enhances precursor dissolution and mass transport, which accelerates the reaction rate and favors the formation of smaller particles. The micro-scope size of the prepared phosphor makes it a potential phosphor candidate as per the point of view of WLED. The similarity between the sizes derived from XRD and SEM suggests that the particles are well crystalline.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eEDS elemental mapping (Figure S3) showed that both Sr, Tb, Na and K were uniformly dispersed throughout the corresponding crystals and no other impurities were observed. This indicates that the Tb atoms are atomically dispersed within the compound.\u003c/p\u003e \u003cp\u003eTo investigate the luminescence properties of Tb\u003csup\u003e3+\u003c/sup\u003e doped SrWO\u003csub\u003e4\u003c/sub\u003e phosphor, a series of samples were prepared. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea is the excitation spectrum of the SrWO\u003csub\u003e4\u003c/sub\u003e sample at room temperature with the monitoring wavelength at 435 nm, and the scanning range is 300\u0026ndash;400 nm. The excitation band of WO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e is observed at 320\u0026ndash;390 nm, resulting from the \u003csup\u003e1\u003c/sup\u003eA\u003csub\u003e1\u003c/sub\u003e\u0026rarr;\u003csup\u003e1\u003c/sup\u003eT\u003csub\u003e2\u003c/sub\u003e energy transition\u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e, which coincides with the absorption spectrum due to the internal electronic transition in WO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb is the emission spectrum of the SrWO\u003csub\u003e4\u003c/sub\u003e phosphor excited at 275 nm. The scanning area is 300\u0026ndash;700 nm. As shown in the figure, four characteristic peaks located at 411 nm, 438 nm, 468 nm and 477 nm can be observed within the broad absorption band spanning 330\u0026ndash;600 nm, which are attributed to the \u003cb\u003e\u0026sup3;T₂\u0026rarr;\u0026sup1;A₁ electron transition\u003c/b\u003e of the WO₄\u0026sup2;⁻ ion\u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eIn Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec, the excitation spectrum of SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb phosphor monitored at 545 nm has a scanning range of 300\u0026ndash;520 nm. The presence of the strong band at 303 nm of the WO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e group in the excitation spectrum of Tb\u003csup\u003e3+\u003c/sup\u003e ions means that there is an energy transfer from the O\u003csup\u003e2\u0026minus;\u003c/sup\u003e to W\u003csup\u003e6+\u003c/sup\u003e and the one from O\u003csup\u003e2\u0026minus;\u003c/sup\u003e to Tb\u003csup\u003e3+\u003c/sup\u003e. In the region of 300\u0026ndash;500 nm, there are some peaks ascribed to the f\u0026ndash;f transitions of Tb\u003csup\u003e3+\u003c/sup\u003e, which are assigned to the electron transition from the \u003csup\u003e7\u003c/sup\u003eF\u003csub\u003e6\u003c/sub\u003e ground state to the different excitation states as 303 nm \u003csup\u003e5\u003c/sup\u003eH\u003csub\u003e4\u003c/sub\u003e, 319 nm \u003csup\u003e5\u003c/sup\u003eH\u003csub\u003e7\u003c/sub\u003e, 340 nm \u003csup\u003e5\u003c/sup\u003eG\u003csub\u003e2\u003c/sub\u003e, 352 nm \u003csup\u003e5\u003c/sup\u003eD\u003csub\u003e2\u003c/sub\u003e, 360 nm \u003csup\u003e5\u003c/sup\u003eG\u003csub\u003e5\u003c/sub\u003e, 369 nm \u003csup\u003e5\u003c/sup\u003eG\u003csub\u003e6\u003c/sub\u003e, 379 nm \u003csup\u003e5\u003c/sup\u003eD\u003csub\u003e3\u003c/sub\u003e and 488 nm \u003csup\u003e5\u003c/sup\u003eD\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e. According to the results obtained from the excitation spectrum, 369 nm is chosen as the host sensitization wavelength for the evaluation of the photoluminescence emission characteristics of the SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb\u003csup\u003e3+\u003c/sup\u003esamples. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed depicts the emission spectra which consists of four well-defined emission peaks at 489 nm (blue, \u003csup\u003e5\u003c/sup\u003eD\u003csub\u003e4\u003c/sub\u003e\u0026rarr;\u003csup\u003e7\u003c/sup\u003eF\u003csub\u003e6\u003c/sub\u003e), 545 nm (green, \u003csup\u003e5\u003c/sup\u003eD4\u0026rarr;\u003csup\u003e7\u003c/sup\u003eF\u003csub\u003e5\u003c/sub\u003e), 587 nm (yellow, \u003csup\u003e5\u003c/sup\u003eD\u003csub\u003e4\u003c/sub\u003e\u0026rarr;\u003csup\u003e7\u003c/sup\u003eF\u003csub\u003e4\u003c/sub\u003e), and 621 nm (red, \u003csup\u003e5\u003c/sup\u003eD\u003csub\u003e4\u003c/sub\u003e\u0026rarr;\u003csup\u003e7\u003c/sup\u003eF\u003csub\u003e3\u003c/sub\u003e) due to the distinct intra-configurational \u003csup\u003e4\u003c/sup\u003ef\u003csub\u003e8\u003c/sub\u003e -\u003csup\u003e4\u003c/sup\u003ef\u003csub\u003e8\u003c/sub\u003e transitions of Tb\u003csup\u003e3+\u003c/sup\u003e ions in the host\u003csup\u003e[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e. Among these peaks, the green emission corresponds to the \u003csup\u003e5\u003c/sup\u003eD\u003csub\u003e4\u003c/sub\u003e\u0026rarr;\u003csup\u003e7\u003c/sup\u003eF\u003csub\u003e5\u003c/sub\u003e induced electric dipole transition. This transition is a magnetic dipole transition, following the selection rule Δ\u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;\u0026plusmn;\u0026thinsp;1 and is not dependent on crystal environment\u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e. The 438 nm emission peak has been attributed to \u003csup\u003e5\u003c/sup\u003eD\u003csub\u003e3\u003c/sub\u003e\u0026ndash;\u003csup\u003e7\u003c/sup\u003eF\u003csub\u003e4\u003c/sub\u003e of Tb\u003csup\u003e3+\u003c/sup\u003e ions in several studies\u003csup\u003e[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e; however, drawing on the majority of literature\u003csup\u003e[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e and the unique emission signature of WO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e ( Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb and Figure S3), we interpret this peak as originating from WO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e rather than Tb\u003csup\u003e3+[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/sup\u003e. Hence the synthesized Tb\u003csup\u003e3+\u003c/sup\u003e doped SrWO\u003csub\u003e4\u003c/sub\u003e samples can be used as a potential candidate for WLED application as a green source\u003csup\u003e[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eHere, the energy transfer from WO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e to Tb\u003csup\u003e3+\u003c/sup\u003e is highly efficient and proceeds via three primary mechanisms\u003csup\u003e[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]\u003c/sup\u003e. The distinct emission spectrum arises from a sequential three-step process: initially, WO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e absorbs ultraviolet light; subsequently, the absorbed energy is transferred to Tb\u003csup\u003e3+\u003c/sup\u003e ions; and finally, this energy induces the de-excitation of Tb\u003csup\u003e3+\u003c/sup\u003e ions. Furthermore, a strong and broad excitation band in the ultraviolet region, combined with the characteristic emission of Tb\u003csup\u003e3+\u003c/sup\u003e, enhances the effective excitation of terbium through the sensitizer. From the emission spectra (Figure S4), it is evident that the emission intensity increases as the Tb\u003csup\u003e3+\u003c/sup\u003e concentration rises from 0.1% to 0.4%, then decreases from 0.7% up to 10% doping. This decline in intensity is attributed to concentration quenching\u003csup\u003e[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/sup\u003e, which becomes significant at higher doping levels. Consequently, PL excitation and emission studies indicate that 0.4% represents the optimal doping concentration for the SrWO₄:x% Tb\u003csup\u003e3+\u003c/sup\u003e phosphor.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eWhen trivalent Tb\u003csup\u003e3+\u003c/sup\u003e ions replace divalent Sr\u003csup\u003e2+\u003c/sup\u003e ions in the main lattice, it leads to a charge imbalance. The defects or trap states caused by charge imbalance suppress luminescence efficiency, thereby reducing luminescence intensity\u003csup\u003e[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/sup\u003e. To address this issue, we introduced alkali metal ions (Li\u003csup\u003e+\u003c/sup\u003e, Na\u003csup\u003e+\u003c/sup\u003e and K\u003csup\u003e+\u003c/sup\u003e) as charge compensators. By co-doping alkali metal ions, we effectively neutralized the charge imbalance, thereby stabilizing the crystal structure and changing luminescence intensity. There are no differences in the shape and location of the peaks in the emission spectra between SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb\u003csup\u003e3+\u003c/sup\u003e and SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, 0.5%K. Interestingly, not all alkali metals systematically enhance\u003csup\u003e[\u003cspan additionalcitationids=\"CR19\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]\u003c/sup\u003e or quench\u003csup\u003e[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003e the luminescence. The emission intensity is dependent on both the identity of the alkali metal and the molar ratio of the dopants\u003csup\u003e[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/sup\u003e. The incorporation of varying amounts of Li (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea) and Na (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb) consistently reduced the fluorescence intensity. In contrast, a potassium concentration of 0.5% mol enhanced the fluorescence emission intensity, producing a 1.83-fold increase (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec and \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ed). At higher concentrations (1% mol and 3% mol), however, the fluorescence intensity decreased (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec). Additionally, under a 0.5 mol% doping level, a clear trend is observed: a larger alkali ion radius (K⁺ \u0026gt; Na⁺ \u0026gt; Li⁺) corresponds to a higher Tb\u0026sup3;⁺ PL intensity, suggesting a role for charge compensation effects (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ed).\u003c/p\u003e \u003cp\u003eEnhanced luminescence can be attributed to the following mechanisms\u003csup\u003e[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/sup\u003e. Firstly, charge compensation is achieved through the co-doping mechanism described by the substitution Tb\u003csup\u003e3\u003c/sup\u003e⁺ + K⁺ \u0026rarr; 2Sr\u003csup\u003e2+\u003c/sup\u003e, which directly contributes to an increase in the emission intensity. Secondly, the incorporation of K⁺ ions help suppress the formation of vacancy defects that typically result from the substitution of Tb\u003csup\u003e3\u003c/sup\u003e⁺ for Sr\u003csup\u003e2+\u003c/sup\u003e. Thirdly, doping with K⁺ ions induce a lattice expansion, as evidenced by an increased unit cell volume and interionic spacing. This structural effect reduces non‑radiative relaxation pathways for the Tb\u0026sup3;⁺ ions, thereby further enhancing the overall luminous efficiency.\u003c/p\u003e \u003cp\u003eBased on established literature\u003csup\u003e[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/sup\u003e, the doping of alkali metal ions introduces oxygen vacancies into the host lattice. Due to strong hybridization of charge-transfer states, these vacancies act as efficient sensitizers, promoting energy transfer and thereby significantly enhancing the 4f\u0026ndash;4f transition efficiency of Tb\u003csup\u003e3+\u003c/sup\u003e. This supports that larger ionic radii facilitate the formation of continuous energy-transfer pathways. The luminescence decay observed in the Li⁺ and Na\u003csup\u003e+\u003c/sup\u003e-doped system, however, may be attributed to the small ionic radius of Li⁺ and Na\u003csup\u003e+\u003c/sup\u003e, which allows a portion of Li⁺ and Na\u003csup\u003e+\u003c/sup\u003e ions to occupy interstitial lattice sites. Such off-site occupancy induces localized lattice distortion and stress, which hinders effective energy transfer and enhances non-radiative relaxation of Tb\u0026sup3;⁺ ions, ultimately leading to a decrease in luminescence intensity.\u003c/p\u003e \u003cp\u003eThe average lifetimes of SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, 0.5%A (A\u0026thinsp;=\u0026thinsp;Li, Na, K) and SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb phosphors at 545 nm are calculated to be 1.28 ms (Li), 1.31 ms (Na), 10.26 ms (K) and 2.33 ms, respectively (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ee, Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The change trend of the average lifetime is SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb,0.5%K\u0026thinsp;\u0026gt;\u0026thinsp;SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb\u0026thinsp;\u0026gt;\u0026thinsp;SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb,0.5%Na\u0026gt; SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb,0.5%Li, which is consistent with the emission intensity of the phosphor. This may be because K\u003csup\u003e+\u003c/sup\u003e can reduce the non-radiative transition of Tb\u003csup\u003e3+\u003c/sup\u003e ions, while the special doping position of Li\u003csup\u003e+\u003c/sup\u003e and Na\u003csup\u003e+\u003c/sup\u003e gradually increases the possibility of non-radiative transition.\u003c/p\u003e \u003cp\u003eThe color changes were further annotated using the Commission Internationale de l'\u0026Eacute;clairage (CIE) coordinates as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ef, as the position shifted from (0.19, 0.18) of SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb to (0.19, 0.19) of SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, 0.5% Li (0.21, 0.24) of SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, 0.5% Na and then to (0.22, 0.36) of SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, 0.5% K.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFinally, quantum efficiencies of the samples were evaluated and listed in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Highest efficiency was observed in SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb and SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, 0.5%A (A\u0026thinsp;=\u0026thinsp;Li, Na, K) sample and all these results agree with emission intensities of the samples (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ed). As summarized in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, K⁺ doping at 0.5 mol% induces a 4.4-fold enhancement in luminescence lifetime and a 153% increase in photoluminescence quantum yield.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eLuminescence lifetimes and quantum efficiencies of SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb and SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, 0.5%A (A\u0026thinsp;=\u0026thinsp;Li, Na, K) samples.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSamples\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLifetimes\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eQuantum efficiency\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.33 ms\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e34.90%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb, 0.5% Li\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.28 ms\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e28.28%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSrWO4:0.4%Tb, 0.5% Na\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.31 ms\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e31.76%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSrWO4:0.4%Tb, 0.5% K\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10.28 ms\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e53.40%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn summary, SrWO\u003csub\u003e4\u003c/sub\u003e:xTb, yA (where x\u0026thinsp;=\u0026thinsp;0.1% mol, 0.4% mol, 0.7% mol, 1% mol, 3% mol, 5% mol, 7% mol, 10% mol; A\u0026thinsp;=\u0026thinsp;Li, Na, K; y\u0026thinsp;=\u0026thinsp;0, 0.5% mol, 1% mol, 3% mol) phosphors were synthesized using the solid state synthesis method and their phase purity was confirmed by X-ray diffraction analysis. The particles synthesized by SEM-EDS analysis were about 2\u0026ndash;20 \u0026micro;m in size and possess an irregular morphology. Sr, W, O and Tb were confirmed in the component analysis, and it was found that the doped Tb was evenly distributed by mapping. Examination of the luminescent properties of terbium-doped samples showed expected excitation and emission spectrum with highest emission peak at 544 nm attributable to \u003csup\u003e5\u003c/sup\u003eD\u003csub\u003e4\u003c/sub\u003e \u0026rarr;\u003csup\u003e7\u003c/sup\u003eF\u003csub\u003e5\u003c/sub\u003e transition. Comparison of emission intensities revealed that most intensive luminescence was observed in SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb sample. Charge compensation is achieved through the introduction of Group IA ions (Li⁺, Na⁺, or K⁺), which generally results in a slight reduction in emission intensity. Doping with 0.5 mol% K\u003csup\u003e+\u003c/sup\u003e ions yielded a 1.8-fold increase in mechanical strength, a 4.4-fold enhancement in operational lifespan, and a 153% improvement in quantum yield. The luminescence color of SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb and SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb,0.5%K powders locate at green region in CIE chromatic diagram, so these experimental results imply a potential application of green-emitting optical devices based on SrWO\u003csub\u003e4\u003c/sub\u003e phosphors.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eCompeting interests\u003c/h2\u003e \u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eThe research contributions are as follows: Xiaoxing Ma conducted material synthesis, experimental testing, and manuscript drafting; Ma ( corresponding author) designed the experimental framework and guided thesis composition; Yang performed experimental validation; Zhu ( corresponding author) interpreted experimental outcomes and provided analytical instrumentation; Jiang executed language editing for manuscript refinement.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe data sets used during the current study available from the corresponding author on reasonable request.\u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e\u003cp\u003e\nNone.\u003c/p\u003e\n"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eCUI, R. et al. 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(2020).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLIU, H. et al. K\u0026thinsp;+\u0026thinsp;Co-doped Ca2LaTaO6: RE3+(RE\u0026thinsp;=\u0026thinsp;Pr, Tb) Phosphors: Enhancement photoluminescence intensity and high thermal stability [J]. \u003cem\u003eCeram. Int.\u003c/em\u003e \u003cb\u003e51\u003c/b\u003e (21), 32701\u0026ndash;32710 (2025).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLI, Q. et al. \u003cem\u003eRattling effect mechanism on the temperature stability of low-sintered Ca1\u0026ndash;x(Li1/2Eu1/2)xWO4 microwave dielectric ceramics for dielectric resonant antenna applications [J]\u003c/em\u003e (Journal of Materiomics, 2025).\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":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Lanthanides, Phosphors, Strontium Tungsten Oxide, Luminescence","lastPublishedDoi":"10.21203/rs.3.rs-8884256/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8884256/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eIn this research terbium-doped strontium tungsten oxide samples were synthesized using solid-state synthesis method. It was found through X-Ray powder diffraction (XRD) that the samples belong to the tetragonal crystal system and have the space group I4\u003csub\u003e1\u003c/sub\u003e/a. The scanning electron microscope (SEM) images indicate that the Na, K, W and Tb atoms are uniformly distributed throughout the samples. Photoluminescence (PL) measurements were applied for sample characterization. All of them exhibited green emission with highest peak at 545 nm attributable to \u003csup\u003e5\u003c/sup\u003eD\u003csub\u003e4\u003c/sub\u003e\u0026rarr;\u003csup\u003e7\u003c/sup\u003eF\u003csub\u003e5\u003c/sub\u003e transition. The highest emission intensity was observed in SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb sample while higher doping levels resulted in decrease of the PL intensities due to concentration quenching. Samples with additional alkali metal ions for charge compensation were also prepared and their PL properties were measured. Doping with 0.5 mol% K\u003csup\u003e+\u003c/sup\u003e ions yielded a 1.8-fold increase in mechanical strength, a 4.4-fold enhancement in operational lifespan, and a 153% improvement in quantum yield. These results indicate that SrWO\u003csub\u003e4\u003c/sub\u003e:0.4%Tb,0.5%K materials have great potential application as green phosphors in LEDs.\u003c/p\u003e","manuscriptTitle":"Different alkali carbonates on the microstructure and photoluminescence properties of SrWO 4 :Tb 3+ phosphors","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-02 09:27:10","doi":"10.21203/rs.3.rs-8884256/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-03-16T06:42:34+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-13T06:07:37+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-06T13:01:16+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-06T08:45:16+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-05T17:15:00+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-02T08:20:31+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"59416119660933580038028758845371931638","date":"2026-02-27T14:25:06+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"272261026843764664996182985008299091333","date":"2026-02-27T12:05:02+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"292285109040247345840552458731413411266","date":"2026-02-26T07:19:22+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"206595216718673852432888364537841352204","date":"2026-02-25T17:30:28+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"287931823098062849852280564783576837713","date":"2026-02-25T17:30:25+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-02-25T11:47:29+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-02-25T11:45:59+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-02-25T06:56:16+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-02-19T04:22:25+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2026-02-19T00:48:44+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"df257981-e541-470b-b6be-b123b0ded4b2","owner":[],"postedDate":"March 2nd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"in-revision","subjectAreas":[{"id":63588185,"name":"Physical sciences/Chemistry"},{"id":63588186,"name":"Physical sciences/Materials science"},{"id":63588187,"name":"Physical sciences/Nanoscience and technology"},{"id":63588188,"name":"Physical sciences/Physics"}],"tags":[],"updatedAt":"2026-03-16T06:54:24+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-02 09:27:10","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8884256","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8884256","identity":"rs-8884256","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}