Organizational Unit:
School of Materials Science and Engineering

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Now showing 1 - 2 of 2
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    Analysis of Cation Valences and Oxygen Vacancies in Magnetoresistive Oxides by Electron Energy-Loss Spectroscopy
    (Georgia Institute of Technology, 1998) Wang, Z. L. (Zhong Lin) ; Yin, Jinsong ; Berta, Yolande ; Zhang, Jiming
    Magnetic oxides of (La,A)MnO₃ and (La,A)CoO₃ have two typical structural characteristics: cations with mixed valences and oxygen vacancies, which are required to balance the charge introduced by cation doping. The consequences introduced by each can be different, resulting in different properties. It is important to quantitatively determine the percentage of charges balanced by each, but this analysis is rather difficult particularly for thin films. This paper has demonstrated that electron energy-loss spectroscopy (EELS) can be an effective technique for analyzing Mn and Co magnetic oxides with the use of intensity ratio of white lines, leading to a new technique for quantifying oxygen vacancies in functional and smart materials.
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    Studies of Mn valence conversion and oxygen vacancies in La₁₋ₓCaₓMnO₃₋[subscript y] using electron energy-loss spectroscopy
    (Georgia Institute of Technology, 1997-06-23) Wang, Z. L. (Zhong Lin) ; Yin, Jinsong ; Jiang, Yongdong ; Zhang, Jiming
    Using the white line intensities, electron energy-loss spectroscopy in a transmission electron microscope has been employed to characterize the valence conversion and oxygen vacancies in La₁₋ₓCaₓMnO₃₋[subscript y]. For a nominal doping composition x = 0.33, the ratio of Mn³⁺ to Mn⁴ ⁺ is determined to be more than 0.25 but less than 0.5, and the content of oxygen vacancy y is no more than 0.065 (equivalent to 2.2 at. % of the oxygen content). At y[subscript max] = 0.065, 60% of the residual charge introduced by Ca doping is balanced by the conversion of Mn³⁺ to Mn⁴ ⁺and 40% by oxygen vacancy.