Crystallization of LiAlSiO4 Glass in Hydrothermal Environments at Gigapascal Pressures-Dense Hydrous Aluminosilicates.
Crystallization of LiAlSiO4 Glass in Hydrothermal Environments at Gigapascal Pressures-Dense Hydrous Aluminosilicates.
复制标题
LiAlSiO4 玻璃在吉帕压力水热环境中的结晶-致密水合铝硅酸盐。
DOI：
10.1021/acs.inorgchem.6b01181
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发表时间：
2016
影响因子：
4.6
通讯作者：
U. Häussermann
中科院分区：
文献类型：
--
作者：
K. Spektor;A. Fischer;U. Häussermann
高压水热环境可以大大降低相变的动力学约束，并在相对较低的温度下提供氧化物的高压改性。在某些情况下，这样的环境允许获得动力学上有利的相，包括具有作为羟基结合的水的含水相。我们研究了在0.25-10 GPa的压力范围和200 - 600 °C的温度下，在大量过量水的存在下玻璃的结晶。通过粉末X射线衍射、扫描电子显微镜和红外光谱分析p和T淬火样品。在0.25- 2GPa压力下，低温和高温下分别得到了亚稳的Li-ABW沸石和稳定的α-锂霞石，其晶体结构以四面体配位的Al和Si原子为基础。在5GPa下，LiAlSiO_4生成新的水合相LiAlSiO_3（OH）_2 = LiAlSiO_4·H_2O。其晶体结构由单晶X射线衍射数据表征（空间群P21/c，a = 9.547（3）B = 14.461（5），c = 5.062（2），β = 104.36（1）°）。单斜结构类似于α-锂辉石（LiAlSi 2 O 6），并构成角凝聚的SiO 4四面体链和共享边缘的AlO 6八面体链的交替层。OH基团是八面体Al配位的一部分，并延伸到SiO 4四面体链层内提供的通道中。在10 GPa下，产生了另一种目前结构未知的LiAlSiO 4水合相。水合形式的LiAlSiO 4的形成显示了在千兆帕压力下的水热环境创造真正新材料的潜力。在这种特定情况下，它表明通常获得辉石型铝硅酸盐的可能性与晶体量的羟基结合。这也可能对地球科学产生影响，因为它代表了地球深处的水储存和运输机制。
High-pressure hydrothermal environments can drastically reduce the kinetic constraints of phase transitions and afford high-pressure modifications of oxides at comparatively low temperatures. Under certain circumstances such environments allow access to kinetically favored phases, including hydrous ones with water incorporated as hydroxyl. We studied the crystallization of glass in the presence of a large excess of water in the pressure range of 0.25-10 GPa and at temperatures from 200 to 600 °C. The p and T quenched samples were analyzed by powder X-ray diffraction, scanning electron microscopy, and IR spectroscopy. At pressures of 0.25-2 GPa metastable zeolite Li-ABW and stable α-eucryptite are obtained at low and high temperatures, respectively, with crystal structures based on tetrahedrally coordinated Al and Si atoms. At 5 GPa a new, hydrous phase of LiAlSiO4, LiAlSiO3(OH)2 = LiAlSiO4·H2O, is produced. Its crystal structure was characterized from single-crystal X-ray diffraction data (space group P21/c, a = 9.547(3) Å, b = 14.461(5) Å, c = 5.062(2) Å, β = 104.36(1)°). The monoclinic structure resembles that of α-spodumene (LiAlSi2O6) and constitutes alternating layers of chains of corner-condensed SiO4 tetrahedra and chains of edge-sharing AlO6 octahedra. OH groups are part of the octahedral Al coordination and extend into channels provided within the SiO4 tetrahedron chain layers. At 10 GPa another hydrous phase of LiAlSiO4 with presently unknown structure is produced. The formation of hydrous forms of LiAlSiO4 shows the potential of hydrothermal environments at gigapascal pressures for creating truly new materials. In this particular case it indicates the possibility of generally accessing pyroxene-type aluminosilicates with crystallographic amounts of hydroxyl incorporated. This could also have implications to geosciences by representing a mechanism of water storage and transport in the depths of the Earth.