Experimental manifestations of the Nb.sup.4+./sup.-O.sup.-./sup. polaronic excitons in KTa.sub.0.988./sub.Nb.sub.0.012./sub.O.sub.3./sub..

0368223 - FZÚ 2012 RIV US eng J - Journal Article
Yusupov, R.V. - Gracheva, I.N. - Rodionov, A.A. - Syrnikov, P. P. - Gubaev, A. I. - Dejneka, Alexandr - Jastrabík, Lubomír - Trepakov, V.A. - Salakhov, M.K.
Experimental manifestations of the Nb⁴⁺-O^- polaronic excitons in KTa_0.988Nb_0.012O₃.
Physical Review. B. Roč. 84, č. 17 (2011), 174118/1-174118/7. ISSN 1098-0121
R&D Projects: GA MŠMT(CZ) 1M06002
Institutional research plan: CEZ:AV0Z10100522
Keywords : photoinduced EPR * Nb⁴⁺-O^- polaronic excitons * KTa_0.988Nb_0.012O₃
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 3.691, year: 2011

The formation of the photopolaronic excitons has been detected experimentally by means of the photoinduced EPR studies of KTa0.988Nb0.012O3 crystals.The signal is attributed to the single trapped charge carriers.The anisotropic spectrum is caused by the axial centers oriented along the C4 axes.The anisotropic spectrum is attributed to the Nb4+-O- polaronic excitons.The temperature dependence of the anisotropic component is characterized by two activation energies: the internal dynamics activation energy (3.7 meV), which makes the EPR spectrum unobservable above 10 K, and the destruction energy (52 meV).By comparing the anisotropic photo-EPR spectrum and the photoinduced optical absorption temperature dependencies, we found that the Nb4+-O- polaronic excitons also manifested themselves via the wide absorption band at ~ 0.7 eV arising under ultraviolet light excitation.Klíčová slova: photoinduced EPR, Nb4+-O- polaronic excitons , KTa0.988Nb0.012O3
Permanent Link: http://hdl.handle.net/11104/0202622