Meng Fancheng, Liu Yahui, Wang Lina, Chen Desheng, Zhao Hongxin, Zhen Yulan, Chen Jing, Qi Tao
National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China.
State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming 650093, China.
Materials (Basel). 2021 Apr 27;14(9):2259. doi: 10.3390/ma14092259.
Natisite (NaTiSiO) is a layered sodium titanosilicate containing TiO square pyramids. The structure evolution of natisite in water and acid solutions is the basis for its potential applications. With NaSiO as the silicon source, natisite with the shape of the square sheet was selectively prepared from the hydrothermal method with 14.3 mol/L NaOH solution at 240 °C. Natisite has 20 Raman active modes and 22 infrared active modes from the first-principles calculations within density functional theory, and the calculated Raman and infrared spectra agree well with the experimental ones. The characteristic Raman peak at 844 cm is caused by the symmetric stretching of the apical Ti-O bond in the TiO unit, assigning to and modes. Natisite remains relatively stable in water with a sodium leaching percentage of lower than 6%. When washing with sulfuric acid solutions, the interlayer spacing of natisite is reduced due to the extensive removal of sodium ions, and an intermediate composed of SiO and newly formed TiO units may be formed. Moreover, after washing with water and acid solutions, 95.5%, 63.4%, and 35.2% of Na, Si, and Ti in natisite can be leached in total, respectively, resulting in the structural disintegration of natisite.
钠钛硅石（NaTiSiO）是一种含有TiO四方锥的层状钠钛硅酸盐。钠钛硅石在水和酸溶液中的结构演变是其潜在应用的基础。以NaSiO为硅源，在240℃下用14.3mol/L的NaOH溶液通过水热法选择性制备了方形片状的钠钛硅石。基于密度泛函理论的第一性原理计算表明，钠钛硅石有20个拉曼活性模式和22个红外活性模式，计算得到的拉曼光谱和红外光谱与实验结果吻合良好。844cm处的特征拉曼峰是由TiO单元中顶端Ti-O键的对称拉伸引起的，归属为和模式。钠钛硅石在水中相对稳定，钠浸出率低于6%。用硫酸溶液洗涤时，由于大量钠离子的去除，钠钛硅石的层间距减小，可能形成由SiO和新形成的TiO单元组成的中间体。此外，用水和酸溶液洗涤后，钠钛硅石中Na、Si和Ti的总浸出率分别可达95.5%、63.4%和35.2%，导致钠钛硅石结构解体。
