(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.