Birefringence Measurements of the Uniaxial-Stress Dependence of the Incommensurate Phase Transition in K₂SeO₄

Authors

D. P. Billesbach, University of Nebraska-LincolnFollow
F. G. Ullman, University of Nebraska-Lincoln
John R. Hardy, University of Nebraska-LincolnFollow

Date of this Version

8-1-1985

Comments

Published in Physical Review B Volume 32, Number 3, 1 August 1985. Copyright © 1985 The American Physical Society. Used by permission.

Abstract

The uniaxial-stress dependence of the incommensurate-phase-transition temperature (at 130 K) in K₂SeO₄ was measured along all three crystal axes by observation of the anomalies in the birefringence caused by the structure change. The results for the c-axis-stress dependence (- 17.0±0.2 K/kbar) agree with previous studies of other workers. This experiment has also provided the first direct measurements of the a-axis- and b-axis-stress dependences (+ 3.1 ±0.2 K/kbar and +7.7± 0.2 K/kbar, respectively). Also, a value of -6.2±0.3 K/kbar was calculated from these data for the dependence of the transition temperature on hydrostatic pressure. This is in agreement with hydrostatic-pressure measurements and thus confirms the reliability of the uniaxial-stress results.