Control of the degree of long-range compositional order in ceramics of the compound perovskites Pb(B′1/2B″1/2)O3 using recrystallization

It is established that an ordered state forms in Pb(Yb_1/2Nb_1/2)O₃ at fairly low temperatures (650–800°C). Subsequent high-temperature heat treatment of the ceramic without additives (sintering or additional annealing) does not produce any significant change in the degree of long-range compositional order s because of the low diffusion rate of the Yb and Nb ions. The addition of Li₂CO₃, which forms a liquid phase, creates conditions for the dissolution of grains with a high value of s, the nucleation of new crystallization centers, and the growth of grains with a new equilibrium value of s at the sintering (annealing) temperature. Zh. Tekh. Fiz. 69, 24–30 (March 1999)