Mixed-crystal lattice dynamics of Hf_xTi_1-xSe₂

Authors

Vanvilai Katkanant, University of Nebraska - Lincoln
Roger D. Kirby, University of Nebraska-LincolnFollow

Date of this Version

July 1989

Comments

Published Phys. Rev. B 40, 1152 (1989). Permission to use.

Abstract

The first-order Raman spectra of the mixed-crystal layered compound Hf_xTi_1-xSe₂ have been studied over the whole range of concentrations 0≤x≤1. Both pure compounds, TiSe₂ and HfSe₂, have the CdI₂ structure and so have two Raman-active phonons of A_1g phonon is at about 205 cm ^-1. As x is decreased from 1.0, a new Raman peak, of A_1g symmetry, appears near 180 cm ^-1. As x is decreased further, this peak shifts smoothly upwards in frequency, until it finally merges (by x=0.05) with the pure TiSe₂ A_1g phonon. A modified random-element isodisplacement model involving only short-range forces is developed to describe the observed concentration dependences of the frequencies of these phonons. The calculated concentration dependences are in good quantitative agreement with the experimental results.