1:1 Ordered Domain Growth in Pb(Mg1/3Ta2/3)O3‐La(Mg2/3Ta1/3)O3 Relaxor Ferroelectric Perovskites

Single‐phase perovskite solid solutions are formed across the entire (1 ‐ x )Pb(Mg _1/3 Ta _2/3 )O ₃ ‐ x La(Mg _2/3 Ta _1/3 )O ₃ (PLMT) pseudobinary system. Although as‐sintered (1300°C, 3 h) samples with x lessthan equal to 0.1 adopt a phase‐separated, “PMN‐type” microstructure comprising small (2‐3 nm) ordered domains dispersed in a disordered matrix, extensive domain growth and complete order can be induced by extended thermal annealing (1300°C, 24 h). These observations, and the alterations in the thermal stability and domain size across the system, can be interpreted using a charge‐balanced random site model for the cation order. No evidence is found to support the space‐charge models currently used to describe the cation ordering and properties of the corresponding niobate systems.