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NIR Absorption of Nb 4+ Polarons in Reduced SBN Crystals
Author(s) -
Gao M.,
Kapphan S.,
Pankrath R.,
Zhao J.
Publication year - 2000
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/(sici)1521-3951(200002)217:2<999::aid-pssb999>3.0.co;2-6
Subject(s) - polaron , absorption (acoustics) , materials science , oscillator strength , absorption spectroscopy , absorption band , analytical chemistry (journal) , condensed matter physics , chemistry , optics , physics , spectral line , composite material , electron , chromatography , quantum mechanics , astronomy
A stable broad absorption band around 0.72 eV, assigned to the absorption of Nb 4+ polarons, is observed in pure SBN, SBN:Cr or SBN:Ce crystals after previous reduction treatment at T < 800 °C in Ar, vacuum or H 2 . The absorption spectrum of Nb 4+ polarons in reduced SBN crystals shows a considerable dichroism, which exists even far above room temperature. The peak position and the integrated absorption of Nb 4+ polarons are measured as a function of temperature. The maximum of the Nb 4+ polaron absorption shifts to higher energies with decreasing temperature. A comparison of optical absorption and recent literature values [1] of the magnetic susceptibility and therefore concentration of polarons yields values of the optical oscillator strength estimated to be f ≈ (5 ± 0.6) × 10 2 .