Wydział Chemii

Janusz Przesławski

Bogdan Kosturek

Sławomir Dacko

Ryszard Jakubas

2007

Solid State Communications

142

713-717

10.1016/j.ssc.2007.04.033

Naukowa

Angielski

Artykuł

Thermal (specific heat) and optical (linear birefringence) studies were performed for a new ferroelectric crystal (C₃N₂H₅)₅Bi₂Cl₁₁. Two phase transitions were confirmed and described. The first-order paraelastic–ferroelastic phase transition at 360 K was studied with a polarizing microscope. The continuous second-order phase transition at 165 K to the ferroelectric phase is described by the Landau model using specific heat and linear birefringence data. The Landau expansion coefficients and are of an order of magnitude higher than the closely related ferroelectric crystal; MAPCB — (CH₃NH₃)₅Bi₂Cl₁₁. Thermal parameters (such as the excess enthalpy and the excess entropy ) of the continuous transition were estimated and discussed. The ‘two-site’ model describing the motion of three of the five imidazolium cations, which is proposed from the structural studies, is fully confirmed by the data from the ac-calorimetric measurements.

Ferroelectrics, Heat capacity, Optical properties

https://doi.org/10.1016/j.ssc.2007.04.033

http://www.elsevier.com