Morphology Control During Heat Treatment of GeTe-PbTe Alloys

Abstract

Abstract Microstructural evolution of GexPb1–xTe (x=0.5, 0.87, 0.9) alloys with respect to spinodal decomposition and continuous/discontinuous precipitation is investigated. Solution treatment at 630 °C for 10 days leads to a single-phase grain structure with homogeneous concentration distribution. In Ge0.5Pb0.5Te, after aging at 300, 400, and 450 °C for 3 days a lamellar spinodally decomposed microstructure was observed. For the alloys with higher Ge content, a diffusion controlled decomposition of the supersaturated solid solution occurs, during which two different microstructures form either simultaneously or separately. Inside the miscibility gap, but outside the spinodal line, a nucleation and growth mechanism leads to continuous and discontinuous precipitation at the grain boundaries, followed by continuous precipitation in the grain interior.