摘要

The effects of Mn2+ doping on the structural, optical and magnetic properties of the corundum-related oxide Zn3TeO6 were investigated. Polycrystalline ceramic samples of the solid solution Zn3-xMnxTeO6 (0<x <= 2.0) were prepared by a solid-state reaction route. Phase diagram as a function of Mn concentration indicates monoclinic (C2/c) structure for x<1.0, disproportionated mixing of both monoclinic (C2/c) and rhombohedral (R-3) structure for 1.0 <= x <= 1.6, and R-3 structure for x >= 1.8. Moreover, when x=2.0, ZnMn2TeO6 was formed, in which the bond length of Te-O and Mn/Zn-O increased, and the Mn/ZnO6 octahedra became more distorted. Rietveld refinements of the crystal structures from the powder X-ray diffraction (XRD) data showed that the Zn/MnO6 octahedra were highly distorted in R-3 phase. With the increase of Mn2+ doping content, the solid solution Zn3-xMnxTeO6 demonstrated not only the structure change from C2/c to R-3, but also the color evolution from light yellow to dark yellow. In optical absorption spectroscopy, with the increase of Mn2+ doping concentration, the absorption at 400-550 nm was enhanced, and the optical band gap of the samples gradually decreased from 3.25 eV (x=0.1) to 2.08 eV (x=2.0). Analysis revealed that the color of samples changed from light yellow to dark yellow is due to the d-d transition of Mn2+ ions in Zn/MnO6 octahedron. Magnetic measurements indicate that the antiferromagnetic transition temperature of the solid solution gradually increased with the increase of the doping amount of Mn2+, and the doped Mn2+ ions exist in a high spin state.

  • 单位
    中山大学

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