Crystal structure and electrical properties of (Li, Ce, Nd)-multidoped CaBi2Nb2O9 high temperature ceramics

(Li, Ce, and Nd)-multidoped CaBi2Nb2O9 (CBN) Aurivillius phase ceramics were prepared via a conventional solid-state sintering route. The crystal structure including bond lengths and bond angles, microstructure, dielectric constant, DC resistivity, and piezoelectric properties were systematically investigated. Rietveld-refinements of X-ray results indicated that small quantity of (Li, Ce, Nd) doping (< 2.5 mol%) increases orthorhombic distortion, because of the smaller ionic radii of doping ions. However, orthorhombic distortion obviously decreased with increasing (Li, Ce, Nd) doping concentration from 5 to 25 mol%. The replacement of asymmetric A-site Bi3+ with 6s2 lone pair electrons by symmetric Li+, Ce3+ and Nd3+ ions decreased the orthorhombic distortion. The morphologies and electrical properties of sintered ceramics were tailored by the introducing (Li, Ce, Nd) multi-dopants. The improvement of piezoelectric properties of modified-CBN ceramics were attributed to decreasing grain sizes and morphotropic phase boundary (MPB). Ca0.85(Li0.5Ce0.25Nd0.25)0.15Bi2Nb2O9 (CBNLCN-15) ceramics had optimum properties, and d33 and Tc values were found to be ~ 13.1 pC/N and ~ 900 °C, respectively.