Synthesis, Structural and Dielectric Studies on SrBi2-xGdxNb2O9 Lead Free Ceramics

In this manuscript, the structural and dielectric properties of Gadolinium (Gd 3+ ) substituted at Bi-site of SrBi 2-x Gd x Nb 2 O 9 (x= 0.0, 0.4, 0.6 and 0.8) prepared by using solid state reaction are studied. XRD analysis revealed the formation of single phase with orthorhombic structure in SBN and Gadolinium modified SBN. It is found that cell parameters and volume were decreased with increase of Gd 3+ ion concentration in SBN. SEM analysis revealed that the samples possess well defined needle shaped grains. The grain size of SBN was hindered by the presence of Gd 3+ ion at Bi-site. The growth of single phase layered perovskite structure was confirmed from FTIR and Raman spectroscopy. The dielectric properties of Gd 3+ ion doped SBN ceramics are studied as a function of frequency (50Hz-1MHz) from room temperature to 500ºC. It is observed that phase transition temperature (T c ) decreased from 430ºC to 330ºC with increase of frequency due to incorporation of Gd 3+ ion in SBN. The broadness of peaks and decrease in T c indicate the transition from a normal ferroelectric to ferroelectric-relaxor type. The study on variation of tanδ with temperature at different frequencies indicates that tanδ has larger values at higher temperatures. Further, the diffuseness parameter (γ) has been computed for all the compositions.