Interfacial Reactions in Ni/PbSe

PbSe-based alloys are promising thermoelectric materials, and in these materials, nickel is commonly used as barrier layer. This study investigates the interfacial reactions in Ni/PbSe couples reacted at 250 degrees C, 300 degrees C, 350 degrees C and 400 degrees C. The reaction couples are prepared by electroplating a Ni layer on PbSe substrates. Experimental results show that one reaction phase, Ni3Pb2Se2, is formed in the Ni/PbSe couples reacted at 300 degrees C, 350 degrees C and 400 degrees C, but no interfacial reaction occurs at 250 degrees C. The reaction layer grows thicker with higher temperature and longer reaction time. The growth rate constants at 300 degrees C, 350 degrees C and 400 degrees C are 1.8, 3.5 and 11.8 mu m/root d, respectively. It is concluded that the reaction path is Ni/Ni3Pb2Se2/PbSe, and that nickel is the fastest diffusion species in the Ni/PbSe couples.