Study of vibrational modes in CuxAg1-xIn5S8 mixed crystals by infrared reflection measurements


INDIAN JOURNAL OF PHYSICS, vol.92, no.4, pp.431-435, 2018 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 92 Issue: 4
  • Publication Date: 2018
  • Doi Number: 10.1007/s12648-017-1114-z
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.431-435
  • Keywords: Semiconductors, Crystal growth, Phonons, Optical spectroscopy, CUIN5S8 SINGLE-CRYSTALS, AGIN5S8 THIN-FILMS, PHYSICAL-PROPERTIES, GROWTH, SPECTRA, SPINELS
  • Middle East Technical University Affiliated: Yes


Infrared reflection spectra of CuxAg1-xIn5S8 mixed crystals, grown by Bridgman method, were studied in the wide frequency range of 50-2000 cm(-1). All four infrared-active modes were detected, which are in full agreement with the prediction of group-theoretical analysis. Real and imaginary parts of the dielectric function, refractive index and the energy losses function were evaluated from reflectivity measurements. The frequencies of TO and LO modes and oscillator strengths were also determined. The bands detected in IR spectra of studied crystals were assigned to various vibration types (valence and valence-deformation) on the basis of the symmetrized displacements of atoms obtained employing the Melvin projection operators. The linear dependencies of optical mode frequencies on the composition of CuxAg1-xIn5S8 mixed crystals were obtained. These dependencies display one-mode behavior.