Synthesis and Characterization of Desified Amorphous Phasee

根据本研究项目，我们进行了以下三个方面的研究：1）在Ge六配位稳定的温度范围内，对GeO_2和Li_2O-3GeO_2玻璃进行了压缩，压缩温度为27 - 500 ℃，压缩压力为30 GPa。GeO_2和Li_2O-3GeO_2玻璃的致密度分别达到10%和15%。高压下回收的Li_2O-3GeO_2玻璃的Ge EXAFS测量表明Ge的配位数为4。EXAFS测定的第二和第三近邻距离（Ge-Gel和Ge-Ge 2）表明，致密化机制是由于GeO_4四面体的扭曲堆积。在Li_2O-3GeO_2和GeO_2玻璃中，压缩引起的配位变化是可逆的。利用高压差热分析（HP-DTA）系统和多砧高压装置，对锗酸盐玻璃中锗的熔点进行了测定，并对锗酸盐玻璃中锗的熔点进行了分析 关于我们 在<nu>800 ℃和2.5GPa、769 ℃和3.5GPa、752 ℃和4.0GPa、686 ℃和5.0GPa、596 ℃和6.0GPa的温度和压力条件下，我们检测到吸热峰。通过原位X射线研究，在730 ℃、4.32GPa和640 ℃、5.81GPa下观察到了氢氧钙石的熔融。HP-DTA和X射线研究的结果在其实验误差范围内是和谐的。熔融曲线呈负梯度，表明在此压力范围内，液态Ca（OH）_2的密度高于氢氧化钙的密度。3）用光子工厂的同步辐射高压装置，测量了金刚石和白锡型锗在高温高压下K边附近的EXAFS谱。根据金刚石型Ge的等温状态方程，在0.4GPa的精度范围内，估算了10.6GPa的压力值。样品池组件中的压力也通过使用NaCl刻度的X射线衍射实验来确定。金刚石型Ge作为高温EXAFS测量的压力校准剂具有很大的优势，因为谐波近似可以应用到700 ℃。少

According to the present research project, we have pefformed following three studies.1) Glasses of composition GeO_2 and Li_2O-3GeO_2 were compressed up to 30 GPa at temperatures from 27 to 500^oC where sixfold coordination of Ge is stable. Densification of 10 and 15% was achieved for GeO_2 and Li_2O-3GeO_2 glasses, respectively. Ge EXAFS measurements of Li_2O-3GeO_2 glasses retrieved from high pressure indicated that the coordination number of Ge is 4. The second and third neighbor distances (Ge-Gel and Ge-Ge2) determined by EXAFS show that the densification mechanism is explained by more distorted packing of GeO_4 tetrahedra than that in ambient glass. Coordination change by compression in the present Li_2O-3GeO_2 and GeO_2 glasses is reversible. The quenchability of the sixfold coordination of Ge in germanate glass is discussed.2) Using High-Pressure Differential Thermal Analysis (HP-DTA) system with a cubic multi-anvil high pressure apparatus, we measured the melting points of port … More landite, Ca(OH) _<nu> up to 6GPa and 1000ﾟC.We detected endothermic due to meeting peaks at the temperature and pressure conditions of 800ﾟC and 2.5GPa, 769ﾟC and 3.5GPa, 752ﾟC and 4.0GPa, 686ﾟC and 5.0GPa, and 596ﾟC and 6.0GPa. By in-situ x-ray studies under pressure, the melting of portlandite was observed at 730ﾟC and 4.32GPa and at 640ﾟC and 5.81GPa. Results of both HP-DTA and x-ray studies were harmonious within their experimental errors. The melting curve has a negative gradient indicating the higher density of liquid Ca(OH)_2 than that of portlandite in this pressure range.3) EXAFS spectra near the Ge K-edge in diamond and white-tin type Ge under high temperature and pressure were measured using a cubic anvil type high pressure device with synchrotron radiation from thr Photon Factory. Pressure values up to 10.6GPa were estimated on the basis of the isothermal equation of state of the-diamond type Ge within an accuracy of 0.4GPa. Pressures in the sample cell assembly were also determined by X-ray diffraction experiment using the NaCl scale. The diamond type Ge is of great advantage to the pressure calibrant of EXAFS measurements at elevated temperature because a harmonic approximation can be applied up to 700ﾟC. Less