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Title: Observation of high-spin mixed oxidation state of cobalt in ceramic Co{sub 3}TeO{sub 6}

We report coexistence of high spin Co{sup 3+} and Co{sup 2+} in ceramic Co{sub 3}TeO{sub 6} using X-ray Absorption Near Edge Structure (XANES), DC magnetization, and first principles ab-initio calculations. The main absorption line of cobalt Co K-edge XANES spectra, along with a linear combination fit, led us to estimate relative concentration of Co{sup 2+} and Co{sup 3+}as 60:40. The pre edge feature of XANES spectrum shows crystal field splitting of ∼1.26 eV between e{sub g} and t{sub 2g} states, suggesting a mixture of high spin states of both Co{sup 2+} and Co{sup 3+}. Temperature dependent high field DC magnetization measurements reveal dominant antiferromagnetic order with two Neel temperatures (T{sub N1} ∼ 29 K and T{sub N2} ∼ 18 K), consistent with single crystal study. A larger effective magnetic moment is observed in comparison to that reported for single crystal (which contains only Co{sup 2+}), supports our inference that Co{sup 3+} exists in high spin state. Furthermore, we show that both Co{sup 2+} and Co{sup 3+} being in high spin states constitute a favorable ground state through first principles ab-initio calculations, where Rietveld refined synchrotron X-ray diffraction data are used as input.
Authors:
; ;  [1] ;  [2] ;  [3]
  1. Indus Synchrotrons Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India)
  2. Technical Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)
  3. Atomic and Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)
Publication Date:
OSTI Identifier:
22402730
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 21; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ABSORPTION; ABSORPTION SPECTROSCOPY; ANTIFERROMAGNETISM; CERAMICS; COBALT IONS; CRYSTAL FIELD; GROUND STATES; HIGH SPIN STATES; MAGNETIC MOMENTS; MAGNETIZATION; MIXTURES; MONOCRYSTALS; NEEL TEMPERATURE; SPECTRA; SPIN; TEMPERATURE DEPENDENCE; X RADIATION; X-RAY DIFFRACTION; X-RAY SPECTROSCOPY