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 sing le X-ray powder diffraction pattern using the Rietveld method. The X-ray po wder pattern was composed of 42.7% of AgIn5S8, 32.7% of AgInS2 (tetragonal phase) and 24.6% of AgInS2 (orthorhombic phase). The AgInS2 (tetragonal pha se) crystallizes in the space group I-42d (D-2d(11), No. 122), Z = 4, with unit cell parameters a = 5.8760(2) Angstrom, c = 11.2007(7) Angstrom, V = 3 86.73(3) Angstrom (3). The AgInS2 (orthorhombic phase) crystallizes in the space group Pna2(1) (C-2v(9), No. 33), Z = 4, with a = 6.9972(6) Angstrom, b = 8.2733(6) Angstrom, c = 6.6939(6) Angstrom, V 387.51(6) Angstrom (3). T he AgIn5S8 crystallizes in the space group Fd-3m O-h(7), No. 227), Z = 8, w ith a = 10.8265(2) Angstrom, V = 1269.01(4) Angstrom (3). The refinement of 45 instrumental and structural parameters led to R-rho = 9.1%, R-wp = 11.4 %, R-exp = 8.2% and S = 1.4; R-B = 5.6% (AgInS2 tetragonal), R-B = 5.2% (Ag InS2 orthorhombic), R-B = 8.9% (AgIn5S8 cubic), for 162, 540, and 110 indep endent reflections, respectively. (C) 2001 Elsevier Science Ltd. All rights reserved.