Metal‐Insulator Transition in Titanium Disulphide Crystals

Abstract

A temperature induced metal (M) → insulator (I) transition is investigated which is possibly first of its kind in the titanium rich titanium disulphide crystals confirming to the composition Ti1.17S2. This transition is established by monitoring the temperature dependence of the electrical conductivity and the thermoelectric power. The structural characteristics at room temperature and at high temperatures (≈ 573 K) also are explored through electron diffraction. The M → I transition is believed tooccur due to the increase of disorder which occurs at high temperature where the short range order state of excess Ti atoms in the van der Waals gapgives rise to a highly disordered amorphous like state. This may lead toshifting of the mobility edge from below the Fermi energy to above the Fermienergy, thus leading to the observed M → I transition. Copyright © 1986 WILEY‐VCH Verlag GmbH & Co. KGaA