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キーワード:
Chemistry; Crystallography;
要旨:
Single crystals of new compound RbFe5(MoO4)(7) were successfully grown by the flux method, and their crystal structure was determined using the X-ray single-crystal diffraction technique. The XRD analysis showed that the compound crystallizes in the monoclinic space group P2(1)/m, with unit cell parameters a = 6.8987(4), b = 21.2912(12) and c = 8.6833(5) angstrom, beta = 102.1896(18)degrees, V = 1246.66(12) angstrom(3), Z (molecule number in the unit cell) = 2, R-factor (reliability factor) = 0.0166, and T = 293(2) K. Raman spectra were collected on the single crystal to show the local symmetry of MoO4 tetrahedra, after the confirmation of crystal composition using energy dispersive X-ray spectroscopy (EDS). The polycrystalline samples were synthesized by a solid-state reaction in the Ar atmosphere; the particle size and thermal stability were investigated by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) analyses. The compound decomposes above 1073 K in an Ar atmosphere with the formation of Fe(iii) molybdate. The thermal expansion coefficient along the c direction has the value alpha = -1.3 ppm K-1 over the temperature range of 298-473 K. Magnetic measurements revealed two maxima in the magnetization below 20 K, and paramagnetic behavior above 50 K with the calculated paramagnetic moment of 12.7 mu B per formula unit is in good agreement with the presence of 3Fe(3+) and 2Fe(2+) in the high-spin (HS) state. The electronic structure of RbFe5(MoO4)(7) is comparatively evaluated using X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations.
