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      Permanent link:
      https://www.ias.ac.in/article/fulltext/jcsc/103/05/0613-0619

    • Keywords

       

      EPR; apophyllite; vanadyl; bonding parameters; annealing

    • Abstract

       

      Single crystal EPR spectra of a natural mineral, apophyllite, containing VO(II) ion as an impurity have been investigated. The EPR spectra of the mineral, as obtained, was complex in nature, but was simplified by annealing the crystals at 490 K. The EPR parameters of the VO(II) species in the annealed crystal,g∥ = 1.924 (2);g⊥ = 1.983 (2);A∥ = 18.35 (5); andA⊥ = 7.24 (5)mT, are very close to a typical VO(II) impurity. Theoretically calculated line positions, using second-order hyperfine terms in the spin Hamiltonian with an axially symmetricg andA tensor values, agreed very well with the experimental ones. The EPR analysis of the annealed crystal has further revealed that the most preferred location of the VO(II) impurity is a substitutional Ca(II) site. The calculated bonding parameters and admixture coefficients indicate a fair amount of covalent bonding in the complex.

    • Author Affiliations

       

      Geetha Ramakrishnan1 M B V L N Swamy1 P Sambasiva Rao1 S Subramanian1

      1. Regional Sophisticated Instrumentation Centre, Indian Institute of Technology, Madras - 600 036, India

    • Dates

       
      Published
      October 1991
      Manuscript received
      28 November 1990
      Manuscript revised
      5 April 1991

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