Study the effect of B-site dopant on dielectric properties of lead free piezoceramics with high curie temperature

摘要

In the present work effect of Nb doping on dielectric properties of BNT was studied. ((Bi_0.5Na_0.5)_1-0.05xTi_1-xNb_xO₃with × = 0 to 0.08) was synthesized by conventional solid state reaction technique. The effect of Nb doping was investigated for x = 0, 0.01, 0.02, 0.04, 0.06 & 0.08 mol. Calcination was done at 870°C. XRD analysis of calcined powders confirms the formation of rhombohedral structure. Calcined powders were compacted uniaxially. Green density of compacted samples was > 60% of theoretical density (5.97 g/cc). Green samples were then sintered at temperature range of (1100-1180)°C. Sintered density was found (94-96) %. At room temperature dielectric losses were found in the range of 10^-2indicating the low loss material. Optimum properties were found at x=0.04 with dielectric constant of 815, dielectric losses of 0.05 and Curie temperature (T_c~ 320°C) at room temperature and measuring frequency of 1kHz. Diffusion coefficient "γ" lies between 1.1 to 1.6 for all compositions along with temperature deviation from Curie-Weiss law (21-33)°C confirming all compositions have ferroelectric properties of relaxer behavior.