The spinodal decomposition in the BST system

A study of Ba1-xSrxTiO3 solid solutions (0.00 <= x <= 1.00) prepared by conventional ceramic technology have been performed. By the X-ray diffraction method, a discrepancy between the phase diagram (room temperature) of the quasi-binary system BaTiO3-SrTiO3 and the well-known phase diagram is established. According to the latter, at x approximate to 0.3, there is a transition from the tetragonal phase to the cubic phase. Our study revealed a splitting of diffraction peaks in the cubic phase (0.3 < x < 0.7), a bimodal distribution of particles in solid solutions, and sinusoidal modulation of the structure. The concentration dependences of the coherent-scattering region and the microstrains do not correspond to the phase transition by the of nucleation and growth mechanism -> The ferroelectric. paraelectric phase transition in the solid solutions with x = 0.1, 0.2 is a first-order transition, and with x = 0.3, it is the second-order transition or close to it. The dielectric spectra of solid solutions with x = 0.1 and x = 0.2 are characterized by strong dispersion, an increase in the dielectric constant at low frequencies and a giant increase dielectric constant in the solid solution with x = 0.2. The conclusion about spinodal decomposition of Ba1-xSrxTiO3 solid solutions in the range of 0.275 <= x < 0.800 at room temperature was made. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The study of Ba1-xSrxTiO3 solid solutions prepared by conventional ceramic technology shows discrepancies in structure, phase transitions, and dielectric properties, compared to the well-known phase diagram. With varying x values, the solid solutions exhibit different characteristics in structure, phase transitions, and dielectric behaviors.