Growth of orthorhombic and tetragonal modifications of TlInS₂ from its monoclinic phase

Abstract

Orthorhombic (O) and tetragonal (T) modifications of TlInS2 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), P212121 and P41212 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‐TlInS2 (Eg = 2.52 ± 0.01 eV) is slightly higher whereas that of T‐TlInS2 (Eg = 1.87 ± 0.01 eV) is noticeably lower than the band gap of M‐TlInS2. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Влияние химического состава кристаллов TlIn-=SUB=-1-x-=/SUB=-Er-=SUB=-x-=/SUB=-S-=SUB=-2-=/SUB=- (0≤ x≤0.01) на их диэлектрические характеристики и параметры локализованных состояний

“…В кристалле TlInS 2 ионно-ковалентные связи происходят между атомами, тогда как слабые ван-дер-ваальсовые связи создаются между последовательными двумерными слоями, которые перпендикулярны направлению (001). Согласно [2,3] пространственная группа C 6 2h характеризует кристаллическую симметрию TlInS 2 , которая имеет моноклинную структуру при комнатной температуре.…”

γ-Radiation Stimulated Structural Transition of Monoclinic TlInS2 to Hexagonal Phase

“…[1][2][3][4] The growth conditions for any of the above-listed modifications of TlInS 2 are already known. 5,6) Almost all A 3 B 3 C 2 6 crystals with layered or chain structure undergo a ferroelectric phase transition (FPT) accompanied by anomalies in temperature dependencies of the various parameters including dielectric function, "ðT Þ, and conductivity, ðT Þ. It has been shown 7) that various "ðT Þ-dependences observed so far on different samples of M-TllnS 2 are due to its different polytypes.…”