Simultaneous Rietveld refinement of three phases in the Ag-In-S semiconducting system from X-ray powder diffraction

Three phases of the Ag-In-S system were simultaneously refined from a single X-ray powder diffraction pattern using the Rietveld method. The X-ray powder pattern was composed of 42.7% of AgIn5S8, 32.7% of AgInS2 (tetragonal phase) and 24.6% of AgInS2 (orthorhombic phase). The AgInS2 (tetragonal phase) crystallizes in the space group I-42d (D112d, No. 122), Z = 4, with unit cell parameters a = 5.8760(2) إ, c = 11.2007(7) إ, V = 386.73(3) إ3. The AgInS2 (orthorhombic phase) crystallizes in the space group Pna21 (C92v, No. 33), Z = 4, with a = 6.9972(6) إ, b = 8.2733(6) إ, c = 6.6939(6) إ, V = 387.51(6) إ3. The AgIn5S8 crystallizes in the space group Fd-3m (O7h, No. 227), Z = 8, with a = 10.8265(2) إ, V = 1269.01(4) إ3. The refinement of 45 instrumental and structural parameters led to Rp = 9.1%, Rwp = 11.4%, Rexp = 8.2% and S = 1.4; RB = 5.6% (AgInS2 tetragonal), RB = 5.2% (AgInS2 orthorhombic), RB = 8.9% (AgIn5S8 cubic), for 162, 540, and 110 independent reflections, respectively.