Thermal properties of (PbySn1-y)2P2(SexS1-x)6 crystals with tricritical Lifshitz point on a phase diagram

A brief survey of the data on thermal properties of (PbySn1-y)2P2(SexS1-x)6 crystal is presented. On the basis of experimental phonon-state density values, the temperature dependence of the heat capacity has been calculated, and estimates of Debye temperatures, Gruneisen parameters and Lindeman constants are presented. The concentration transformation of specific heat for crystals under study has been investigated for the isovalent replacements within a wide temperature range including phase transitions (PT). Critical behaviour of heat capacity in the vicinity of the PT has been studied. Data on thermal expansion coefficient values and thermal conductivity are given. Results obtained have been analysed with consideration for the proximity of phase transitions to the tricritical Lifshitz point.

Keywords:

• Thermal properties
• phase transition
• critical behavior
• ferroelectrics
• tricritical Lifshitz point
• phase diagram