Electrical resistivity of Cu doped As-Se glasses at high pressure

Abstract

Electrical resistivity measurements have been performed on Cu_xAs₄₀Se_60-x glasses with x between 0 and 28 at% of Cu. The resistivity of these glasses continuously decreases and saturates at higher quasi-hydrostatic pressures. The pressure derivative of the electrical resistivity shows distinct changes as a function of composition; a large change for the initial addition of Cu (≤ 10 at% Cu) and levelling off for higher content of Cu. To understand this, Differential Scanning Calorimetric (DSC) and thermal crystallization studies have been carried out on all these glasses. Thermal crystallization of As-Se glasses with 5 and 10 at% Cu results in crystalline Cu₃AsSe₄ and As₂Se₃ phases, whereas glasses with 15 and 20 at% of Cu crystallize into Cu₃AsSe₄ phase only. Glasses with 25 and 28 at% of Cu yield a new binary Cu₂As₃ and the ternary Cu₃AsSe₄ phase. These structural differences arising as a function of composition are reflected in the pressure derivative of the resistivity of the glasses.