Reaction evolution and alternating layer formation in Sn/(Bi0.25Sb0.75)2Te3 and Sn/Sb2Te3 couples

► Interfacial reactions in Sn/(Bi0.25Sb0.75)2Te3 and Sn/Sb2Te3 at 250 °C are examined. ► The growth rates of the reaction layer are extremely fast. ► The initial reaction product is SnTe phase with nano-size pores filled with liquid. ► A self-assembled Sn3Sb2/SnTe alternating layer is formed for longer reaction time.