The charge ordering effect in LuFe_(2)O_(4) powder is investigated with the vibrating sample magnetometer and Mossbauer spectroscopy. The crystal structure of LuFe_(2)O_(4) shows the two-dimensional layered type rhombohedral(R3m) structure. The lattice constants are found to be a_(0)velence3.439 A and c_(0)velence25.258 A by the Rietveld refinement. The Neel temperature (T_(N)) is determined to be 250 K. The Mossbauer spectra consist of four sextets indicating the magnetic ordering below T_(N), where three sets are assumed to be Fe~(3+) phases and the other is Fe~(2+) at 4.2 K, and two doublets splitting in a paramagnetic region. At room temperature, the electric quadrupole splittings ((DELTA)E_(Q)) of two doublets are 0.22 +- 0.01 and 0.67 +- 0.01 mm/s, respectively. The isomer shift value of a doublet with smaller (DELTA)E_(Q) is 0.18 +- 0.01 mm/s relative to the Fe metal, which is consistent with the Fe~(3+) valence state, while the value of a doublet with larger (DELTA)E_(Q) is 0.83 +- 0.01 mm/s indicating Fe~(2+) state. The Mossbauer spectra suggest that the observed asymmetry below 370 K is due to the charge ordering effect between Fe~(2+) and Fe~(3).
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