Phase equilibria of Cu-In-SeII. The In-In2Se3-Cu2Se-Cu subsystem

In three subsequent publications we report new results on the phase equilib ria of Cu-In-Se. This work, part II, deals with the subsystem In-In2Se3-Cu2 SeCu. For this subsystem we show and discuss the liquidus, a reaction schem e of the phase equilibria, five isopleths, and one isothermal section of th e ternary phase diagram at 500 degrees C. The subsystem includes twenty-eig ht four-phase equilibria. Twenty of these involve a liquid phase (sixteen t ransition planes, two ternary eutectia, two ternary monotectica). Moreover, we have determined thirteen critical tie lines and twenty-one different su rfaces of primary crystallization within the liquidus. The miscibility gaps in the In-rich and the Cu-rich parts of the binary component systems, resp ectively, are continuously linked with each other. The phase equilibria of the In-In2Se3-Cu2Se-Cu subsystem are largely determined by eutectic, metate ctic, and monotectic critical tie lines. In particular, metatectic and mono tectic critical tie lines lead to two primary crystallization surfaces of t he alpha phase (CuInSe2), which is of particular importance for photovoltai c applications.