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Specific features of the optical spectra in Tl 2 In 2 S 3 Se layered single crystals
Author(s) -
Gasanly N. M.,
Guler I.,
Goksen K.
Publication year - 2007
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.200610874
Subject(s) - refractive index , monoclinic crystal system , dispersion (optics) , oscillator strength , anisotropy , band gap , analytical chemistry (journal) , absorption (acoustics) , spectral line , materials science , absorption spectroscopy , diffraction , chemistry , optics , molecular physics , crystallography , optoelectronics , crystal structure , physics , chromatography , astronomy
The optical properties of Tl 2 In 2 S 3 Se layered single crystals have been studied by means of transmission and reflection measurements in the wavelength range of 450‐1100 nm. The analysis of the absorption data revealed the presence of both optical indirect and direct transitions with energy band gaps of 2.16 and 2.42 eV, respectively. The observed coexistence of indirect and direct energy band gaps is related to the anisotropy of the Tl‐containing layered crystals. The dispersion of the refractive index is discussed in terms of the Wemple‐DiDomenico single‐effective‐oscillator model. The refractive index dispersion parameters: oscillator energy, dispersion energy, oscillator strength and zero‐frequency refractive index were found to be 4.78 eV, 43.58 eV, 13.18 × 10 13 m –2 and 3.18, respectively. From X‐ray powder diffraction study, the parameters of monoclinic unit cell were determined. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)