The effect of temperature and pressure on the optical absorption edge in Cu6PS5X (X=Cl, Br, I) crystals

✍ Scribed by I.P. Studenyak; M. Kranjčec; Gy.S. Kovács; V.V. Pan'ko; I.D. Desnica; A.G. Slivka; P.P. Guranich

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 200 KB
• Volume: 60
• Category: Article
• ISSN: 0022-3697
• DOI: 10.1016/s0022-3697(99)00220-6

✦ Synopsis

The absorption edge of monocrystalline Cu 6 PS 5 X X Cl; Br; I superionic ferroelastics was studied in the 77-303 K temperature range and the mechanisms of exciton-phonon interactions resulting in exponential absorption edges and Urbach tails were analysed. Various types of disordering, affecting the optical absorption tails, were studied. The investigation of the influence of hydrostatic pressure (up to 400 MPa) on optical transitions of Cu 6 PS 5 X at 295 K revealed that the increase of pressure causes an increase of the optical pseudogap as well as the increase of the slope of the absorption edge indicating pronounced ordering in most disordered crystals. Data obtained from the pressure studies confirmed the predominant contribution of exciton-phonon interaction to the temperature shift of the Urbach absorption edge.