Elastic and dielectric responses of VDF₇₀/Tr₃₀ near ferroelectric phase transition

Abstract

The infra-low frequency elastic modulus and the complex dielectric permittivity of vinylidene fluoride trifluoroethylene VDF₇₀/Tr₃₀, are studied within the temperature range of 20 ÷ 140 °C. The experimental results are used to determine the temperature dependence of order parameter η near the Curie temperature (T_c). It is revealed that spontaneous polarization P_s and spontaneous strain x_s are linearly coupled. The dielectric dispersion, due to the relaxation dynamics of polar microregions in the vicinity of the T_c, is found. The average relaxation time follows the Arrhenius law with activation energy depending on temperature.

Keywords:

• Polar copolymer
• elastic modulus
• phase transition
• spontaneous polarization and strain
• dielectric relaxation

Additional information

Funding

This study was supported partly by the Ministry of Science and Higher Education of the Russian Federation within studies over State task of Federal Scientific Research Center “Crystallography and Photonics”, Russian Academy of Sciences.