Phase coexistence in highly deuterated ferroelectric triglycine selenate: Landau description

Departamento de Física de la Materia Condensada, Instituto Mixto de Ciencia de Materiales CSIC-Universidad de Sevilla - Apartado 1065, 41080 Sevilla, Spain

Corresponding author: fjromero@us.es

Received: 5 June 2006
Accepted: 3 October 2006

Abstract

The phase transition in a 90% deuterated sample of TGSe has been investigated by calorimetric and dielectric measurements. As a consequence of the presence of an internal crack in the sample, the transition takes place in two stages separated by an interval where the paraelectric and the ferroelectric phases coexist without latent heat contribution. From the latent heat, the specific heat excess and the Curie law for the dielectric constant, it is shown that the transition follows a 2-4-6 Landau potential, whose coefficients are determined. This potential describes completely all the data, including those corresponding to the coexistence interval.