Pressure-induced semimetal-metal and metal-metal transitions in 1T and 2H TaS₂

Abstract

The reversible transition from the semimetallic (1T2) to the metallic (1T1) octahedral form of the layer crystal TaS2 which takes place on heating at 325 K is investigated at pressures up to 60 kbar and in the temperature range 170-330 K. Resistivity data as a function of temperature reveal a semimetal-metal transition under pressure within the 1T2 phase, and a model to account for this result is proposed. A new shear-induced transition under pressure in the trigonal prism metal 2H TaS2 is described, and the resistivity values suggest that 1T1 is the resultant phase at high pressure.