Phase transitions in Li0.13Na0.87NbO3 crystals

Li0.13Na0.87NbO3 crystals were studied by dilatometric, dielectric, acousti c emission, and optical methods on heating in a temperature range from 20 t o 700 degreesC. Based on the results of these measurements, the following s equence of phases was established: 20-350 degreesC, ferroelectric orthorhom bic Pmm2; 350- 400 degreesC, ferroelectric orthorhombic Pmmm; 400-630 degre esC, ferroelectric tetragonal, 14/mmm; above 630 degreesC, cubic Pm3m. The latter two transformations can be classified as second-order ferroelectric phase transitions. (C) 2001 MAIK "Nauka/Interperiodica".