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°C, 300°C, 350°C and 400°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°C, 350°C and 400°C, but no interfacial reaction occurs at 250°C. The reaction layer grows thicker with higher temperature and longer reaction time. The growth rate constants at 300°C, 350°C and 400°C are 1.8, 3.5 and 11.8 μm/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.