Specific heat of NH4Br and NH4BrxCl1-x crystals close to the antiferroelectric transition

Yurtseven H., Yanik A.

JOURNAL OF APPLIED PHYSICS, vol.98, no.9, 2005 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 98 Issue: 9
  • Publication Date: 2005
  • Doi Number: 10.1063/1.1989427
  • Journal Name: JOURNAL OF APPLIED PHYSICS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Middle East Technical University Affiliated: Yes

Abstract

We calculate the specific heat C-VI of NH4Br and mixed crystals of NH4BrxCl1-x using the Ising model for the transition between the disordered (D) and antiferro- (AF) electric phases in these crystalline systems. Our C-VI values, which we calculated for x(Br)=1, 0.26, and 0.51 are in good agreement, both below and above T-C, with the observed C-P data from the literature. Our value of congruent to 0.1 (T < T-C and T>T-C) for the critical exponent of the specific heat agrees with the value of 0.125 predicted by a three-dimensional Ising model.