Light-induced VIS and NIR absorption in SBN : Ce and SBN : Cr crystals

Autor(en): Gao, M
Porcher, S
Pankrath, R
Kapphan, S
Stichwörter: PHOTOREFRACTIVE SR0.61BA0.39NB2O6-CE CRYSTALS; Physics; Physics, Multidisciplinary
Erscheinungsdatum: 1998
Herausgeber: KOREAN PHYSICAL SOC
Journal: JOURNAL OF THE KOREAN PHYSICAL SOCIETY
Volumen: 32
Ausgabe: 2, S
Startseite: S542-S544
Zusammenfassung: 
Congruent Sr0.61Ba0.39Nb2O6 crystals doped with Ce or Cr are investigated under immersion techniques with Fourier spectroscopy in a wide spectral range from UV to FIR. for enhanced light-induced absorption effects leading to photorefractive properties. Spectroscopic evidence is found for the 3+ majority state (FIR Ce3+ spin-orbit and crystal field split 4f transitions and Cr3+ R-lines). The broad polaronic Nb4+ absorption (at 0.78 eV/1.6 mu m), known from reduced SBN, appears also under Ar+-laser illumination at low temperatures (T<140 K). With red Kr+-laser (647 nm) illumination the polaronic Nb4+ absorption for SBN doped with Cc is found to be several orders of magnitude larger than for SBN:Ce, indicating the enhanced red sensitivity of this material. The intervalence transition model Ce3++Nb5+ --> Ce4++Nb4+ must be extended to accomodate new experimental features like nonlinear intensify dependence, non-monoexponential decay kinetics and complicated temperature dependence of the light-induced absorption in the NIR and of new light-induced broad absorption bands in the uv-visible region.
Beschreibung: 
9th International Meeting on Ferroelectricity (IMF-9), SEOUL, SOUTH KOREA, AUG 25-29, 1997
ISSN: 03744884

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