| Summary: | 碩士 === 國立成功大學 === 材料科學及工程學系 === 106 === Suitable synthesis conditions, including the starting chemicals and compositions, applied pressures, reacting temperatures, and times, for the synthesis of a pure phase of (LixFe1-x)OHFeSe were studied. The starting chemicals included pre-synthesized β-FeSe from Se and Fe, LiOH·H2O, and α-FeO(OH) powders. The following ranges of synthesis parameters were attempted: pressure 0.5~1.25 GPa, temperatures from 300~500 ℃, and a reaction time of 24~48 hours. The results indicated that (LixFe1-x)OHFeSe appeared in all samples, but the optimal composition, which contained the highest amount of the desired (LixFe1-x)OHFeSe was β-FeSe:α-FeO(OH):LiOH=1:0.1:1.1. The proper ranges of sintering temperature and external pressure were 300~400℃ and 0.75~1 GPa, respectively. Although it was found that some secondary phases, i.e. δ-FeSe, (Li0.63Fe0.37)FeO2, etc. β-FeSe, one of the starting chemicals, which had usually appeared before, were successfully eliminated from the samples, indicating that it was reacted completely. An anomaly was observed in all of the samples at about 12 K~14 K in the magnetic susceptibility measurements, which was considered to be glassy magnetic behavior. However, no obvious superconductivity was found in either the magnetic and electrical measurements. Based on the x-ray diffraction data, the lattice constants of the synthesized (LixFe1-x)OHFeSe were refined using Total Pattern Analysis Solution (TOPAS) software, allowing the influences of the processing parameters on the lattice constants to be discovered.
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