Optical and dielectric investigations in SBN:Ce

Autor(en): Kapphan, S
Greten, G
Pankrath, R
Herausgeber: Matthews, GE
Williams, RT
Stichwörter: ABSORPTION; Ce3+; CRYSTALS; light-induced adsorption; Materials Science; Materials Science, Multidisciplinary; Nb4+ polarons; NIOBATE; photorefractive; SBN:Ce; TEMPERATURES
Erscheinungsdatum: 1997
Herausgeber: TRANS TECH PUBLICATIONS LTD
Journal: PROCEEDINGS OF THE 13TH INTERNATIONAL CONFERENCE ON DEFECTS IN INSULATING MATERIALS - ICDIM 96
MATERIALS SCIENCE FORUM
Volumen: 239-
Startseite: 321
Seitenende: 324
Zusammenfassung: 
In Sr0.61Ba0.39Nb2O6 (SBN) doping with Ce enhances the photorefractive properties [1]. Many details and microscopic properties of the centers and their interaction with light are not yet sufficiently understood. Fourier-spectroscopy in a wide spectral range from UV to the FIR was employed to investigate the absorption spectra and their change under intensive Ar+-laser light illumination. At about 2200 cm(-1) transitions due to Ce3+ spin orbit split 4f-states display at low temperatures characteristic light induced changes indicative of the Ce3+-oxidation state. A broadband polaronic Nb4+-absorption at about 1.6 mu m, known from reduced SBN crystals, also appears under Ar+-laser illumination at low temperature. Light induced charge transfer processes lead to absorption changes, which can be explained consistently on the basis of a simplified model involving Ce3+/4+-centers and polaronic Nb4+-centers [6]. In addition to the ferroelectric relaxer transition at T = 350 K (4/mmm to 4 mm) a further phase transition (4 mm to m) [7] at low temperature (T approximate to 90 K) has been confirmed by dielectric and pyroelectric measurements. Both phase transition temperatures are shifted to lower values with increasing cerium content.
Beschreibung: 
13th International Conference on Defects in Insulating Materials (ICDIM 96), WAKE FOREST UNIV, WINSTON SALEM, NC, JUL 15-19, 1996
ISBN: 9780878497560
ISSN: 02555476
DOI: 10.4028/www.scientific.net/MSF.239-241.321

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