High pressure synthesis of LixFe1-xOHFeSe and the variation of its properties under different processing parameters

摘要

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 ?-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:?-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

獎項日期	2018 8月 23
原文	English
監督員	Xiao-Ding Qi (Supervisor)