Phase Pattern of Barium Strontium Titanate System and Dielectric Responses of Its Solid Solutions

Resumo

Samples of solid solutions of the system Ba_1–xSr_xTiO₃ (0 ≤ x ≤1.0) are produced by solid-phase synthesis followed by sintering using conventional ceramic technology. Their crystal structure and grain structure are studied at room temperature and dielectric properties – in a wide range of external influences (temperature and frequency of the alternating electric field). Based on these results, the state diagram of the system is constructed including three single-phase fields with different-symmetry (tetragonal, pseudocubic, and cubic) and two morphotropic fields with coexistence of the tetragonal and pseudocubic, pseudocubic and cubic phases. Peculiarities of the grain landscape associated with the formation of morphotropic areas and melting of barium hydroxide are revealed. The dependence of the dielectric properties of solid solutions on their crystal-chemical specifics and position in the phase diagram of the system is demonstrated. A conclusion is made about the possibility of using the compositions with x = 0.2 to create materials with high dielectric constants promising for applications in microelectronics.