K_2NiF_4型La_<2-x>Sr_xMnO_<4+δ>の合成と電気的性質

概要

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Polycrystalline bodies of La_<2-x>Sr_xMn0_<4+δ> (1.0≦x≦2.O) with a K_2NiF_4 structure were prepared by a standard ceramic method. Lattice parameters, electrical conductivity and Seebeck voltage were measured. Fur thermore, optical absorption spectra were recorded to obtain information on changes in the electronic structure in the vicinity of the energy band gap. Changes in lattice parameters were attributed to the disappearance of Jahn Teller distortion of Mn0_6 0ctahedra upon Sr doping. The results suggested that holes doped in the present system were mainly localized on man ganeseions. The temperature dependence of electrical conductivities of all the samples was almost Arrhenius type. Seebeck voltages and optical absorption spectra changed drastically in the composition ranges of 1.0<x< 1.2 and 1.6<x<2.0. It was suggested that the electronic structure near the energy band gap changed drastically in those composition ranges.
社団法人日本セラミックス協会の論文
1995-12-01