Synthesis, X-ray and optical characterizations of two new oxysulfides: LaInS2O and La5In3S9O3

摘要

Two new compounds, LaInS2O and La5In3S9O3 were synthesized in the La-In-S-O quaternary system. Both compounds crystallize in the orthorhombic system with lattice constants a = 20.5421(6) Angstrom, b = 14.8490(4) Angstrom, c = 3.9829(1) Angstrom for LaInS2O, and a = 4.1018(1) Angstrom, b = 26.833(1) Angstrom, c = 16.023(1) Angstrom for La5In3S9O3. The structure of La5In3S9O3 was solved from single-crystal X-ray data, in the space group Pbcm, with Z = 4: it is built from three-atom-thick (100)(NaCl) layers interleaved with fluorite-type ribbons, and is closely related to the structures of the known lanthanum and indium compounds La10In6S17O6 and La4In5S13. Both compounds LaInS2O and La5In3S9O3 exhibit a yellow color; measurement of their optical gaps gave 2.73 and 2.60 eV, respectively. (C) 2003 Elsevier Inc. All rights reserved.