The changeable coordination of structural and bonding characteristics in amorphous Cu2Te from ab initio molecular dynamics simulations

Abstract

Crystalline Cu2Te has recently attracted a great deal of attention owing to its good performance in thermoelectric materials. Yet, knowledge of the amorphous phase is still insufficient, which may restrict its practical application. Here, we have studied the structural and bonding characteristics of amorphous Cu2Te by ab initio molecular dynamics simulations. We show that, compared with its crystal phase, the Cu atoms bond more Cu than Te atoms in amorphous Cu2Te and Te atoms predominantly bond with Cu atoms. In detail, the amorphous Cu2Te is made up of Cu–Te network structures and Cu–Cu high-coordinated configurations, presenting the hexagonal and icosahedral structures, respectively. This result is probably ascribed to both the stronger bonding ability of Cu–Cu bonds and the multivalence of Te atoms. Our findings enrich the knowledge of the local structure and the bonding nature of amorphous Cu2Te, which can guide the design of good performance Cu2Te based thermoelectric devices further.