Abstract
Background: PbTe is an important thermoelectric compound. Ni is commonly used as a barrier layer. To provide fundamental information, an Ni-Pb-Te phase equilibria isothermal section at 650 °C and Ni/PbTe interfacial reactions at 650 o C, 500 o C and 400 o C are determined. Methods: The isothermal section is proposed based on results of equilibrated alloys and related phase diagrams. The interfacial reactions are examined using reaction couples. Significant Findings: There is no ternary compound. At 650 o C, the liquid phase extending from the Pb corner has significant symmetrical solubilities of Ni and Te, and displays a peculiar deep and narrow shape. No interfacial reactions are observed in the Ni/PbTe couple heat-treated at 500 o C and 400 o C for a month. However, significant reactions are observed when reacted at 650 o C. Reaction zone thickness is 120 μm when reacted for 30 min. The reaction zone has many phases, and yet has clear phase region boundaries. Liquid and β-Ni 3 Te 2 phases are formed, and the reaction path is Ni/β-Ni 3 Te 2 +Liquid (I)/Liquid (I)/PbTe. Many phases were formed from solidification when the couple was removed from a furnace. Ni is the dominating diffusion species in the Ni/PbTe couples. Ni penetrates into the PbTe substrate, reacts with Te to form Ni 3 Te 2 , and the liquid phase is formed with excess Pb.