Effect of gadolinium doping on structural, ferroelectric and electrical properties of strontium bismuth niobate ceramics

Abstract

The substitution of gadolinium (Gd3+) at the Bi-site of SBN (SB1.6G0.4N, SB1.4G0.6N, and SB1.2G0.8N) to realize the technical importance of the materials has been presented. The density of the polycrystalline compositions was obtained establishing sintering conditions from solid-state treatment. The monophasic orthorhombic crystal structure was revealed from the XRD study. The SEM morphology indicated well-defined acicular grains with an induced porosity in all the studied samples. Ferroelectric studies were conducted on SBN and Gd3+ modified SBN ceramic samples and observed that the parameters of 2Ps, 2Pr, and 2Ec, have been found to decrease in gadolinium-substituted SBN compared to SBN. The Cole-Cole plots from the impedance measurement are utilized to evaluate Rg, Rgb, Cg, and Cgb. The conduction process in these materials is through Rg but not Rgb as received from the calculations of Rg and Rgb. The Z' versus frequency plots resulted in an incremental change in temperatures. The constant character of Z' at higher temperatures indicates DC conductivity. The Z“ values have been found to drop and move towards the higher frequency side with rising temperature, which may be ascribed to the inhomogeneity of the polycrystalline ceramic samples. An asymmetric change in M' and M” to zero was observed and the broadening peaks indicate non-Debye relaxation in these materials.