The orthorhombic-tetragonal morphotropic phase boundary in high-pressure synthesized BiMg0.5Ti0.5O3–BiZn0.5Ti0.5O3 perovskite solid solutions

Abstract

(1–x)BiMg0.5Ti0.5O3− xBiZn0.5Ti0.5O3 [(1− x)BMT–xBZT] ceramics of perovskite solid solutions, in which BMT and BZT are lead-free structural analogs of PbZrO3 and PbTiO3, respectively, have been synthesized under high pressure. It was found that the as-prepared compositions with a relative BZT content of <75 mol% are orthorhombic (space group Pnnm), while those with a BZT content above this value are tetragonal (P4mm). In the solution with x = 0.75, both phases coexist forming a morphotropic phase boundary (MPB). The compositional dependence of the normalized unit cell volume exhibits a ~5% jump at x = 0.75. At the same time, the microstructure of the obtained (1–x)BMT− xBZT ceramics shows no particular variation with the chemical composition over MPB. Piezoresponse force microscopy measurements indicate the ferroelectric state of the studied materials and allowed one to estimate their intrinsic piezoelectric coefficients.