采用稀释成盐法从富硼浓缩盐卤中合成的镁硼酸盐化合物及其结构与性质（英文）

Synthesis, Structure and Properties of a Magnesium Borate in Concentrated Boron-Bearing Salt Lake Brine by Dilution Method

通过稀释成盐法在富硼浓缩盐卤体系Na-K-Mg-Cl-SO_4中合成了一种新的六硼酸镁Mg[B_6O_7(OH)_6]·5H_2O化合物。根据X射线粉末衍射数据对其晶体结构进行了精修,并采用红外及拉曼光谱法对其结构进行了表征,分析了其光谱及结构特征。结果表明,该化合物由1个Mg原子、1个B_6O_7(OH)_6基团和5个H_2O分子构成,Mg原子以六配位形式与氧结合形成畸变MgO_6八面体构型;热重分析表明,高温分解过程该化合物脱水转化为四硼酸镁MgB_4O_7;通过紫外可见漫反射法求得其禁带宽度为4.44 eV。

A new magnesium borate mineral, Mg[B6O7（OH）6] ·5H2O was synthesized via dilution method from boron-bearing Na-K-Mg-Cl-SO4 salt lakes. The crystal structure of the new phase was solved and refined using X- ray powder diffraction data and characterized with FTIR and Raman. Its asymmetric unit consists of one Mg atom, one B6O7（OH）6 cluster and five H/O molecules. The Mg atom is 6-coordinated with six O atoms to form a MgO6 oetahedron. Thermal gravimetry （TG/DSC） was used to investigate the thermal behavior of the new compound. During the high temperature decomposition process the dehydrated product MgB4O7 formed. The optical absorption characteristic of this new mineral was investigated by UV-Vis spectrometer and its energy gap Es is about 4.44 eV.