Calculation of the ultrasonic frequencies of the q[110] mode for the first-order and tricritical phase transitions in NH4Cl

Yurtseven H. H. , Bas M.

JOURNAL OF MOLECULAR STRUCTURE, vol.525, pp.87-96, 2000 (Peer-Reviewed Journal) identifier identifier

  • Publication Type: Article / Article
  • Volume: 525
  • Publication Date: 2000
  • Doi Number: 10.1016/s0022-2860(00)00420-8
  • Journal Indexes: Science Citation Index Expanded, Scopus
  • Page Numbers: pp.87-96
  • Keywords: ultrasonic frequencies, first-order and tricritical phase transitions, NH4Cl, CRYSTALS


We study here the ultrasonic frequencies of the q[110] mode of NH4Cl, which we have correlated to the volume changes for the first-order and the tricritical phase transitions in this crystal. We calculated the ultrasonic frequencies of this mode by means of our correlations for the pressures of 0, 0.5 and 0.95 kbar in the first order, and for 1.5 kbar in the tricritical phase regions in NH4Cl using the observed data.