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뫼스바우어 분광법을 이용한 LuFe₂O₄의 자발분극과 철 이온의 거동과의 상관관계에 대한 연구
방봉규(Bong Kyu Bang),김철성(Chul Sung Kim),김성백(Sung Baek Kim),S-W. Cheong 한국자기학회 2007 韓國磁氣學會誌 Vol.17 No.1
Single crystalline, LuFe₂O₄, was grown by the floating zone method. The crystal structure was a two-dimensional layered-type rhombohedral (R3mh) structure, with an a? =3.440(2) A and a c? = 25.263(2) A. The magnetic Neel temperature (T<SUB>N</SUB>) was determined to be 250 K. The Mossbauer spectrum at 12 K was fitted with four sextet sets which was resulted from the crystal structure. The spectrum at room temperature consisted of three singlets and a doublet with the electric quadrupole splitting. The isomer shift (δ) value of the singlet was 0.20±0.01 ㎜/s relative to the Fe metal indicating the Fe<SUP>3+</SUP> valence state, and the value of the doublet was 0.70±0.01 mm/s indicating Fe<SUP>2+</SUP>. The Mossbauer absorption area ratio between Fe<SUP>3+</SUP> and Fe<SUP>2+</SUP> at room temperature was 1 : 1. The doublet phase of spectra gradually disappears by up to 360 K. At 360 K, the spectrum shows the singlet phase. We suggested that the spontaneous polarization effect of LuFe₂O₄ was caused by the change of iron behavior.