Development of ultrahigh pressure apparatus based on high pressure produced by constraining expansion due to breaking of bonds between atoms and between molecules

提出了一种超高压装置，其中压力是由物质中的键断裂而产生的约束膨胀产生的。用脉冲钇铝石榴石激光照射由蓝宝石砧胞约束的玻碳。对样品室中红宝石的荧光发射进行了测量。在实验中，我们还用蓝宝石和金刚石砧作为体积约束，测量了金刚石的反射率。研制了一种脉冲x射线衍射装置，用于测量瞬态产生的压力，并将其组装在仪器中。研究结果如下：1。在蓝宝石电池中，压力超过300 GPa的时间约为1毫秒。2. 在金刚石电池中观察到的较宽波长范围内的荧光发射是由红宝石中压力诱导的^4T_2→^4A_2跃迁引起的，这似乎不是由压力诱导的金刚石荧光引起的。3. 在金刚石晶体与砧之间的界面处观察到高反射率表明金刚石的金属化。4. 观察到的金刚石的位错密度与高度变形晶体的位错密度相当，表明金刚石具有较大的塑性变形。5. 根据尼尔森的理论预测，金刚石可能在接近400 GPa的单轴应力下发生金属化。6. 在该装置中产生高压所需的脉冲激光输出比传统方法的输出要小几个数量级。7. 利用脉冲x射线衍射装置可以从极少量的金属粉末中获得衍射数据。8. 金属的晶胞体积可由衍射数据确定。虽然在样品中检测衍射x射线还存在一些技术问题需要解决，但在不久的将来，将开始对terapascal区物质高压相的研究。

An ultrahigh-pressure apparatus is proposed where pressures are generated by constraining expansion due to breaking of bonds in matter. Glassy carbon constrained by a sapphire anvil cell was irradiated through one anvil with a pulsed YAG laser. A measurement of fluorescence emission from a ruby in the sample chamber was made. A measurement of reflectivity of a diamond was also made in the experiment using the sapphire and diamond anvils for volume constraint. A pulsed X-ray diffraction device was developed to measure transiently generated pressures, which was assembled into the apparatus. The results are as follows: 1. Pressures beyond 300 GPa were achieved for 〜1 ms in the sapphire cell. 2. The fluorescence emission over a wide wavelength range observed in the diamond cell arises from the pressure-induced ^4T_2→^4A_2 transition in ruby, which seems not to result from the pressure-induced diamond fluorescence. 3. High reflectivity suggesting the metallization of diamond was observed at the interface between the diamond crystal and anvil. 4. The observed dislocation density for the diamond is comparable to those for highly deformed crystals, suggesting large plastic deformation of the diamond. 5. As is theoretically predicted by Nielsen, the diamond may have metallized at a uniaxial stress near 400 GPa. 6. The output of pulsed laser required to generate high pressures in the apparatus is some orders of magnitude less than those in the conventional methods. 7. Diffraction data can be obtained from a very small amount of metal powder using the pulsed X-ray diffraction device. 8. The volume of the unit cell for the metal can be determined from the diffraction data. Although several technical problems to be settled for detecting diffracted X-ray from a sample still remain, researches on high-pressure phase of matter in the terapascal region will be started in the near future.