Synthesis and Characterization of Desified Amorphous Phasee

根据目前的研究项目，我们进行了以下三项研究。1)在27 ~ 500^oC的温度范围内，将组合物GeO_2和li22o - 3geo_2压缩到30gpa，在此温度范围内，Ge的六倍配位是稳定的。对GeO_2和Li_2O-3GeO_2玻璃分别实现了10%和15%的致密化。高压li22o - 3geo_2玻璃的Ge EXAFS测量表明，Ge配位数为4。用EXAFS测定的第二和第三近邻距离（Ge-Gel和Ge-Ge2）表明，与环境玻璃相比，四面体的扭曲堆积更能解释致密化机制。在Li_2O-3GeO_2和GeO_2玻璃中，压缩引起的配位变化是可逆的。讨论了锗在锗酸盐玻璃中六重配位的可淬性。2)利用高压差热分析（HP-DTA）系统和立方多砧高压仪，测定了port…More土的熔点，Ca(OH) _<nu>高达6GPa， 1000个硫化氢含量。在800 - 2.5GPa、769 - 3.5GPa、752 - 4.0GPa、686 - 5.0GPa和596 - 6.0GPa的温度和压力条件下，我们检测了吸热特性。在压力下，通过原位x射线研究，观察到波特兰石在730、4.32、640、5.81GPa时的熔融过程。HP-DTA和x射线的研究结果在实验误差范围内是一致的。熔融曲线呈负梯度，表明在此压力范围内液态Ca(OH)_2的密度高于硅酸盐。3)利用光子工厂的同步辐射立方砧式高压装置，测量了高温高压下金刚石和白锡型锗k边附近的EXAFS光谱。根据金刚石型Ge的等温状态方程，在0.4GPa的精度范围内估计出了高达10.6GPa的压力值。通过x射线衍射实验，用NaCl标度测定了样品胞组内的压力。金刚石型Ge对于高温下EXAFS测量的压力校准器具有很大的优势，因为谐波近似可以应用到高达700ºC。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