Phase Transitions and Dielectric Properties of Modified BSPT Ceramics

Abstract

Influence of complex NaCl/KCl and CaCl₂/KCl additives (with molar ratios 1:1 and 0.75:0.25, respectively) with low melting temperatures on structure, dielectric and polar properties of ceramic solid solutions on the base of the composition from Morphotropic Phase Boundary in the system (1-x)BiScO₃ - xPbTiO₃ with x = 0.645 (BSPT) was studied. Using the initial BSPT powders prepared from nitrates solutions dense single phase ceramic samples doped by the additives in amounts 5–15 w.% were obtained at 1050°C (2 h). The shift of initial BSPT composition from mixture of rhombohedral and tetragonal phases to tetragonal in case of the NaCl/KCl additives and to pseudocubic (rhombohedral) in case of the CaCl₂/KCl additives was observed. Slight increase in the Curie temperature T_C value from 673 to 681-679 K initiated by the addition of K⁺ ions into A site of perovskite lattice was observed in the samples doped by the NaCl/KCl additives, while monotonous decrease of the T_C value was typical of the compositions doped by the CaCl₂/KCl additives.

Keywords:

• BiScO₃-PbTiO₃ ceramic solid solutions
• morphotropic phase boundary
• NaCl/KCl and CaCl₂/KCl additives
• ferroelectric phase transitions

Funding

The work was supported by the Russian Foundation for Basic Research (Grant 12-03-00388).