LAUSR

The Cu2Te chalcogenide alloy is doped with 2 at. % Ni to increase the charge carrier concentration and then is further doped with 3 at. % Se to reduce the thermal conductivity. The alloys processing is kept simple–vacuum arc melting only to make a dense alloy for characterization. This also results in retaining the as-solidified highly layered structure. The alloys are found to have two polymorphic forms: hexagonal and orthorhombic at room temperature with a superstructure. The fractured surface shows clearly the layered structure with ∼300 nm thick platelet like features stacked together to form large defect free grains. The electrical conductivity increases to ∼7 × 103 S cm−1 due to Ni-doping compared to ∼5 × 103 S cm−1 for the undoped alloy at room temperature. This however decreases to ∼2.5 × 103 S cm−1 due to double doping, i.e., Ni and Se. In both cases, the alloys exhibit a weak metallic behavior with the conductivity decreasing with increasing temperature. The Seebeck coefficient however increases...