An X-ray diffraction study of the system Al₂S₃–In₂S₃ in the In-rich region

A series of samples in the system Al₂S₃–In₂S₃ in the In-rich region have been synthesized and studied by X-ray diffraction. At the lowest values of the Al/In (molar) ratio, r, the existing phase, β, is isostructural with the room-temperature, ordered, tetragonal phase of In₂S₃. As the Al content increases a progressive disorder of cations takes place. For r≳l/10 this disorder is completed and β is replaced with a phase, denoted as α, which is isostructural with the first high-temperature, cubic, phase of In₂S₃. The unit-cell parameters of the ternary β and α alloys, (Al_xIn_{1 − x})₂S₃, decrease linearly as the Al content increases. From r≳1/3 to r~ 2/3 there is a two-phase region, α + γ₁. The hexagonal phase γ₁ is isostructural with AlInS₃, appearing at r = 1, and with the second high-temperature, γ, modification of In₂Se₃. The phase γ₁ also exists in the systems Ga₂Se₃–In₂Se₃ and Al₂Se₃–In₂Se₃ in the In-rich region for the (Ga, Al)/In (molar) ratio greater than ~ 1/50.