Materials Research | |
Vanadium characterization in BTO: V sillenite crystals | |
J.f. Carvalho2  R.w.a. Franco1  C. J. Magon1  L.a.o. Nunes1  F. Pellegrini2  A.c. Hernandes1  | |
[1] ,Universidade Federal de GoiásGoiânia GO ,Brazil | |
关键词: sillenite; photorefractive; defects; BTO; | |
DOI : 10.1590/S1516-14391999000200008 | |
来源: SciELO | |
【 摘 要 】
Visible and Infrared Optical Absorption and Electron Paramagnetic Resonance (EPR) techniques have been used to characterize the intrinsic defects in sillenite type crystals: nominally pure Bi12TiO20 (BTO) and doped with vanadium (BTO:V). Optical quality crystals, with the composition Bi12.04±0.08Ti0.76±0.07V0.16±0.02O20, have been grown. Results obtained by these different techniques have shown unambiguously the 5+ valence state of the vanadium ion in BTO:V crystals. In pure BTO samples, the EPR and optical spectra show strong evidence of the presence of the intrinsic defect BiM3+ + ho+, which consists of a hole h+, mainly located on the oxygen neighbors of the tetrahedrally coordinated Bi3+ ion. After doping with vanadium, results have shown that the characteristic bands, associated to this hole defect center, disappear, suggesting its transformation in single Bi3+. Anisotropy of the EPR spectra , at 20 K, is related to Fe3+ impurities.
【 授权许可】
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