High pressure structural and transport measurements of InTe, GaTe, and InGaTe2

In this paper, the effect of pressure on the transport and structural properties of GaTe, InTe, and InGaTe2 is reported. All materials were found to exhibit pressure-induced structural transitions. For GaTe, the ambient structure transforms to a mixed state at 8GPa, which transforms at 15GPa to an ordered state. InTe, which crystallizes in a tetragonal structure, shows transformations at 6 and 14GPa. InGaTe2, also initially tetragonal, undergoes two transitions at 9.25GPa and 13GPa. These transitions have shown noticeable effects on the transport properties. In particular, the Seebeck coefficient for the solid solution changes sign at the first phase transition. From these results, the thermoelectric figure of merit has been evaluated for each material. For some of these materials (InTe and InGaTe2) this yields a lower efficiency than ambient conditions. However, for GaTe, this has been shown to increase the figure of merit by 14 times to 8GPa. ► We measure the high pressure properties of InTe/GaTe based materials. ► Increasing pressure induces several structural transitions in all materials, which show changes in the transport properties. ► Mixed phases can improve the figure of merit. ► All three materials trend towards metallicity with increasing pressure.