Dielectric and ferroelectric behaviours of Ba(Ti1-xLi x) (O3-3xF3x) ceramics

BaTiO₃ was doped with BaLiF₃ to form a solid solution of Ba(Ti_1-xLi_x)(O_3-3xF_3x ) composition. Special care was taken to prevent hydrolysis during firing. The Curie temperature of the solid solution decreased from 393 (BaTiO₃) to 300 and to 225 K for compositions x=0, x=0.025, and x=0.10, respectively. Temperature dependencies of the dielectric constant for various frequencies are presented. It is seen that the three successive phase transitions of pure barium titanate are preserved for lightly doped materials, while for heavily doped materials only one phase transition can be observed in the same temperature range. Temperature dependences of spontaneous polarization and coercive field, as determined from ultra-low-frequency measurements of hysteresis loops of the materials, are presented