摘要
以天然水镁石矿石为原料,采用高能球磨方法制备了水镁石超细粉体.通过X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)和激光粒度分析(LP)等对水镁石粉体进行了表征,探讨了球磨时间对水镁石平均粒径和晶格结构的影响.采用第一性原理计算方法研究了不同静压对水镁石晶体结构的影响.结果表明:机械外力作用使晶体结构沿[001]方向更易发生畸变;随球磨时间增加,水镁石红外光谱发生蓝移和宽化特征;球磨3h后,样品平均粒径为3.56μm.当理论计算中静水压力增加,晶格常数a线性减小,c非线性减小.水镁石体系的带隙随压强增加而增大,主要是Mg 2p导带向高能方向移动所致.基于不同静水压力下水镁石晶体的Mulliken布居和电子密度差分结果,其强共价键(O—H键)键长随静压增加保持不变;当静压增加到10.9GPa时,H键(H…O′键)发生重排,体系无序程度减小,与实验结果一致.
Ultrafine brucite powder was prepared by the high energy ball-milling method with brucite mineral as raw material.The effect of ball-milling time on the lattice structure and the mean particle size was analyzed by X-ray diffraction(XRD),Fourier-transform infrared spectroscopy(FTIR)and laser particle(LP).The mechanism of different hydrostatic pressures on the crystal structure of brucite was studied by the first principles calculation.The experimental results show that the crystal structure is more easily distorted along the[001]direction with the mechanical activation,and that,with longer ball-milling the peaks of IR spectrum in brucite exhibit blue-shift and broadening,and the ultrafine brucite powder with the mean particle size of 3.56μm is obtained after ball-milling for 3 h.The theoretical results show that the lattice constant a decreases linearly and c decreases nonlinearly as the hydrostatic pressure increases.The band gap increases with the increases in pressure,which is mainly due to the conduction band of Mg 2p shifts to the high energy direction.The comparison of Mulliken population and electronic density difference of brucite crystal at 0 GPa and 10.9 GPa shows that the O-H bond is a strong covalent bond and the bond length remains unchanged with the increase in hydrostatic pressure.When the hydrostatic pressure increasing to 10.9 GPa,the H disorder decreases with the H…O′bond rearrangement,which is consistent with the previous experimental results.
作者
汪月琴
刘银
张明旭
闵凡飞
WANG Yueqin;LIU Yin;ZHANG Mingxu;MIN Fanfei(School of Material Science and Engineering,Anhui University of Science and Technology,Huainan 232001,China;School of Mechanics and optoelectronic Physics,Anhui University of Science and Technology,Huainan 232001,China)
基金
国家自然基金(51474011)
安徽省科技攻关计划项目(1604a0802122)
中国博士后基金(2014M550337)
安徽理工大学青年教师研究基金(QN201504)资助
关键词
水镁石
机械活化
静压
第一性原理
brucite
mechanical activation
hydrostatic pressure
first-principles
