Growth of orthorhombic and tetragonal modifications of TlInS 2 from its monoclinic phase

Orthorhombic (O) and tetragonal (T) modifications of TlInS 2 were grown by sulfur vapor annealing of monoclinic (M) crystals. Lattice parameters and syngony of the grown crystals were determined from X‐ray investigations (Laue, Weissenberg, rocking crystal and powder diffractions). The lattice parameters a = 6.88 Å, b = 14.04 Å, c = 4.02 Å, Z = 4 and a = b = 7.76 Å, c = 26.6 Å, Z = 20 as well as space groups (SG), P2 1 2 1 2 1 and P4 1 2 1 2 were ascribed to O and T modifications, correspondingly. The transition of M‐crystals to O‐ or T‐phase takes place through the intermediate disordered state of M‐phase in which the unit packets with c ≈ 15 Å are randomly positioned along the c‐axis. From photoconductivity (PC) edge it was found that the band gap of O‐TlInS 2 (E g = 2.52 ± 0.01 eV) is slightly higher whereas that of T‐TlInS 2 (E g = 1.87 ± 0.01 eV) is noticeably lower than the band gap of M‐TlInS 2 . (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)