We have performed X-ray powder diffraction measurements in a mixed valence compound of Fe2 BO4 using synchrotron radiation. The diffraction patterns obtained at several temperatures between 85 and 386 K were analyzed by the Rietveld method. The monoclinic-orthorhombic transition, ascribed to charge-ordering of Fe2 + and Fe3 + ions, was confirmed by the temperature dependence of the monoclinic angle β. No superlattice reflection due to the charge-ordering was detected. The temperature dependences of the lattice parameters show anomalies around 270 K as well as the monoclinic-orthorhombic transition temperature of 327-347 K. The structural change around 270 K is attributable to the onset of the partial charge-delocalization.
|ジャーナル||Journal of Magnetism and Magnetic Materials|
|号||2 SUPPL. PART 1|
|出版ステータス||Published - 3月 2007|
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