Temperature dependence of the IR mode frequency calculated from the volume data for DMNaFE

Abstract

We analyze the infrared (IR) frequencies of the internal mode of asymmetric ${\nu }_{\mathit{as}}\left(\mathit{CNC}\right)$ close to phase transition $\left(T_C=167\mathrm{ }\mathrm{K}\right)$ in DMNaFe. By means of the mode Grüneisen parameter $\left({\gamma }_p\right)$, the IR frequencies are calculated from the observed volume data given in the literature. Calculated frequencies are fitted to the observed data for both below and above $T_C$ as the ${\gamma }_p$ varies with the temperature in the low and high temperature phases in this compound. Our results show that the critical behavior of the observed IR frequencies can be explained from the volume data to describe a first order structural phase transition in DMNaFe.

Keywords:

• Structural phase transition
• IR mode frequencies
• DMNaFe