ISSN:
1573-482X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Electrical Engineering, Measurement and Control Technology
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Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract EPR and magnetic susceptibility investigations on the $$x{\text{V}}_{\text{2}} {\text{O}}_{\text{5}} \cdot {\text{(100}} - {\text{x)[2P}}_{\text{2}} {\text{O}}_{\text{5}} \cdot {\text{PbO]}}$$ glass system with 0〈x≤50 mol % were performed. The covalence degree of vanadium bonds was evaluated according to the LC AO-MO model. The changes observed in the EPR spectra with increasing V4+ ion content are explained using a simulation program on the assumption of the superposition of two signals, one with hyperfine structure (hfs) typical for isolated ions and another one consisting of a broad line without hfs characteristic for clustered ions. The hfs is not shown for x〈3mol%V2O5. The EPR data show the presence of V4+ ions in a square-pyramidal co-ordination (C4V) for 3≤x≤20mol%V2O5. The progressive disappearance of hfs for high V2O5 content (〉20 mol %) suggests the increase of the associated ion number coupled by superexchange interactions. This result is consistent with magnetic susceptibility data for 〉3 mol % where the temperature dependence of magnetic susceptibility is described by the Curie–Weiss type law with a negative paramagnetic Curie temperature. The magnetic susceptibility results allowed the estimation of the V4+/V4+ + V5+ ratio in the sample studied.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1008963104126
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