| Autor: |
J.F. Carvalho, R.W.A. Franco, C. J. Magon, L.A.O. Nunes, F. Pellegrini, A.C. Hernandes |
| Jazyk: |
angličtina |
| Rok vydání: |
1999 |
| Předmět: |
|
| Zdroj: |
Materials Research, Vol 2, Iss 2, Pp 87-91 (1999) |
| Druh dokumentu: |
article |
| ISSN: |
1516-1439 |
| DOI: |
10.1590/S1516-14391999000200008 |
| Popis: |
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. |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
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