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

The Raman frequencies of the lattice modes (147 cm-1 and 207 cm-1 are analyzed for the α-β transition in quartz according to a power-law formula with the critical exponent by using the experimental data. The temperature dependence of the Raman frequency is associated with the order parameter (polarization P) for this transition in the quartz crystal. The damping constant of the lattice modes studied here is calculated using the Raman frequencies at various temperatures for the α-β transition in quartz (Tc = 846K) using the soft mode - hard mode and the energy fluctuation models. Our calculations for the damping constant (bandwidths) give an evidence that the lattice mode of the 147 cm -1 exhibits a soft mode behavior for the α-β transition in quartz. Copyright © 2012 De Gruyter