Interfacial reactions in Cu/PbTe and Cu/PbSe couples

Abstract

PbTe and PbSe are important thermoelectric compounds. Cu is commonly used as an electrode material. To provide fundamental information for the devices using these materials, the interfacial reactions in the Cu/PbTe and Cu/PbSe couples are examined. Similar interfacial reactions are observed in these two couples. No interfacial reactions are found in both kinds of couples reacted at 400 °C and 500 °C. There are very significant interfacial reactions in both kinds of couples reacted at 650 °C. The phase equilibria isothermal sections of Cu-Pb-Te and Cu-Pb-Se at 650 °C are proposed for better understanding the respective interfacial reactions. The reaction zone thickness is 160 µm in the Cu/PbTe couple reacted at 650 °C for 3 min, and its reaction path is Cu/Liquid (I)+Cu2Te/Cu2Te/Liquid (II)/PbTe. The reaction zone thickness is 155 µm in the Cu/PbSe couple reacted at 650 °C for 2 min, and its reaction path is Cu/ Liquid (I)+ (Cu)+Cu2Se/Cu2Se+Liquid (I)/Liquid (I)/PbSe. For both kinds of couples, Cu is the dominating diffusion species.