Determination of temperature dependence of lattice parameters at three successive phase transitions m3m-4mm-mm2-3m

Abstract

The temperature dependence of lattice parameters at three structural phase transition was determined from the condition of paraelectric phase macrosymmetry conservation in a polydomain crystal. Three analytical solutions for a second order phase transition are obtained. The analysis of the functions was made on the sample in BaTiO₃. It is shown that one solution corresponds to the tetragonal and rhombohedral phases, the second one corresponds to orthorhombic phase, and the third solution is not realized.

Keywords:

• Ferroelectrics
• temperature dependence of lattice parameters
• macrosymmetry conservation
• BaTiO3