Calculation of the soft-mode frequency for the alpha – beta transition in quartz

Abstract

The ? – ß structural transition occurs in quartz at TC = 846 K. The frequency of the soft mode associated with the volume increase, decreases with increasing temperature as the transition temperature is approached. In this study, we calculate the soft-mode frequency as a function of temperature using the volume data by means of the mode Grüneisen parameter for the ? – ß transition in quartz. Our calculated frequencies of the soft-mode agree with the observed data from the literature. This shows that the method of calculating the soft mode frequency from the crystal volume is adequate, which can explain the soft mode behavior associated with the ? – ß transition in quartz.