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

2001-12-01
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.
JOURNAL OF MOLECULAR STRUCTURE

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We correlate here by means of gamma-Gruneisen relations the volume changes with the ultrasonic frequencies of the q[1 (1) over bar 0] mode of NH4Cl for the first-order phase transition in this crystal. The ultrasonic frequencies were calculated by a method, which we have developed, using the length-change data from the literature at pressures of 0, 0.2, 0.3 and 0.6 kbar in the first-order phase region of NH4Cl.
Citation Formats
H. H. Yurtseven and M. Bas, “Ultrasonic frequency shifts close to the first order and tricritical phase transitions in NH4Cl,” JOURNAL OF MOLECULAR STRUCTURE, pp. 109–116, 2001, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/57613.