Structure of segnetoceramic materials Ba${}_{x}$Pb${}_{1-x}$Fe${}_{0.5}$Nb${}_{0.5}$O${}_3$

The regularities of the phase formation in compounds based on lead ferroniobate in the system BaCO${}_3$–PbO–Fe${}_2$O${}_3$–Nb${}_2$O${}_5$ at the heating in the air were studied. By the method of qualitative X-ray phase analysis, it is established that at the final synthesis temperature of 1373 K, solid solutions of Ba${}_x$Pb${}_{1-x}$Fe${}_{0.5}$Nb${}_{0.5}$O${}_3$ $(0\leq x\leq1.0)$, are formed that are isomorphic to the structure of the distorted perovskite. It is shown that compositions with a molar ratio x<0,06-0,07 at room temperature have a rhombohedral symmetry, and compositions with higher x values crystallize within the framework of tetragonal symmetry. The dielectric properties of ferroelectric ceramics have been studied for the perovskite-like phases obtained.