Electron diffraction and infrared study of the semimetallic layered compound Ti1?xVxSe2 |
| |
Authors: | HP Vaterlaus S Ansermet M Py F Lévy |
| |
Institution: | Laboratoire de Physique Appliquée, EPF-L, Lausanne, Switzerland |
| |
Abstract: | The crystals of the system Ti1?xVxSe2 (C ≤ x ≤ 0.05) undergo a second order structural phase transition. Electron diffraction studies show that the transition temperature decreases with progressive V-doping. The phase transition considerably affects the infrared reflectivity, measured at 300 and 77 K in the spectral range 40 cm?1 to 4000 cm?1.The presence of free carriers and the existence of optical infrared active Eu phonon modes confer their characteristic appearance to the spectra. At room temperature one phonon structure is measured at 143 cm?1. At 77 K a new series of phonon peaks appears up to a V-concentration of 5 % as a direct consequence of superlattice formation.At room temperature the plasma-edge shifts towards higher frequencies as the vanadium concentration increases. This effect is caused by a large increase of , associated with the mixing of impurities. It is indicative of the small density of states at the Fermi level in semimetallic TiSe2. Our results suggest a phase transition driven by lattice dynamical effects. |
| |
Keywords: | |
本文献已被 ScienceDirect 等数据库收录! |