The 4th International Conference on Matter and Radiation at Extremes (ICMRE 2019)

488 / 2019-03-18 19:22:20

The study of structural phase transitions in Cu2-xTe under high pressure

pressure-induced phase transition,Cu2-xTe,crystal structure prediction,X-ray diffraction

Plenary track > High Pressure Physics and Materials Science

Cu2Te is one of the most commonly used as conductive back contacting materials for CdTe solar cells due to the formation of p+ interface with CdTe absorber. First-principle calculations indicate that the stoichiometric Cu2Te spontaneously decomposed to Cu2-xTe with Cu deficiency, which leads to complex structures at ambient conditions. Thereby, the high-pressure behavior has never been reported up to now. Here, combining X-ray diffraction (XRD) technique with extensive first-principles swarm structure search, we investigated the structural phase transition of Cu2-xTe under high-pressure. Inductive coupled plasma emission spectrum (ICP) suggests our sample as Cu1.875Te. The structural refinement with Cu deficiency from XRD unravels that Cu1.875Te undergoes a phase transition from trigonal structure (P-3m1) to tetragonal structure (I4/mmm) at ~ 2.9 GPa, which apply to Cu2-xTe at least in the range of 0≤x≤0.125 according to first-principle calculations. The electronic band structure dispersions indicate metallic character of I4/mmm Cu2Te and Cu1.875Te. I4/mmm phase will reverse to P-3m1 after decompressing to a very low pressure of 0.3 GPa. Meanwhile, the analysis of mechanical and dynamical stability at ambient pressure implies that the I4/mmm phase Cu2Te has potential to be stabilized to ambient conditions as a metastable material, and if so, it is expected to be used as a new candidate material for industrial application.