NIR absorption and light-induced charge transfer in photorefractive Ba0.77Ca0.23TiO3 crystals doped with iron

Autor(en): Wierschem, M
Lindemann, T
Pankrath, R
Kapphan, SE
Stichwörter: barium-calcium-titanate (BCT) crystal; charge transfer model; Fourier-IR spectroscopy; light-induced absorption; Materials Science; Materials Science, Multidisciplinary; Physics; Physics, Condensed Matter; Ti3+ polarons; TRANSPORT
Erscheinungsdatum: 2001
Herausgeber: TAYLOR & FRANCIS LTD
Journal: FERROELECTRICS
Volumen: 264
Ausgabe: 1-4
Startseite: 1973
Seitenende: 1982
Zusammenfassung: 
Barium-calcium-titanate crystals of the congruently melting composition Ba077Ca0.23TiO3 doped with iron to enhance photorefractive properties, is investigated by Fourier IR spectroscopy under Ar+-Laser irradiation at low temperatures. The light-induced absorption in the NIR and visible range (VIS) is investigated as a function of light intensity, temperature and time. The dependence on temperature and on light intensity of the decay of the light-induced absorption after switching-off the laser light reveals a characteristic behaviour. The light induced absorption of Ti3+ polarons around 0.7 eV can be quantitatively fit in its temperature, intensity and time dependence by a simple charge transfer model Fe2++Ti4+ <-> Fe3++Ti3+. The time- and temperature-dependence reveal tunnelling and thermally activated hopping contributions to the polaron decay. At room temperature both, the (NIR) Ti(3+-)polarons and the VIS-Centers are observed to be thermally ionized and no NIR light-induced absorption can be observed any more under steady state conditions.
Beschreibung: 
3rd Asian Meeting on Ferroelectricity (AMF-3), HONG KONG, PEOPLES R CHINA, DEC 12-15, 2000
ISSN: 00150193

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