Ultrasonic frequency shifts close to the first order and tricritical phase transitions in NH4Cl


Yurtseven H., Tari O., Bas M.

JOURNAL OF MOLECULAR STRUCTURE, vol.598, pp.109-116, 2001 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 598
  • Publication Date: 2001
  • Doi Number: 10.1016/s0022-2860(01)00628-7
  • Title of Journal : JOURNAL OF MOLECULAR STRUCTURE
  • Page Numbers: pp.109-116

Abstract

This study examines our spectroscopic modifications of the Pippard relations using the ultrasonic frequencies of the q[110] and q[1 (1) over bar0] modes for the first order phase transition in NH4Cl. We also examine our relations using the ultrasonic frequencies of the q[110] mode for the tricritical phase transition in this crystal. From our plots of the specific heat C-p as a function of the frequency shifts (1/nu)(partial derivative nu/partial derivativeT)(p), we obtain that our spectroscopically modified Pippard relation considered here is satisfied for those phonon modes studied close to the first order and tricritical phase transitions in NH4Cl. (C) 2001 Elsevier Science B.V. All rights reserved.