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We choose nano-Pt in hydrogen environment to explore the size effect on the formation of metal hydrides.At30 GPa,a phase transition in the metal lattice from the cubic to hexagonal phase is observed characterized by a drastically increased volume per metal atom,indicating the formation of PtH-P6_3/mmc.We find that nano-Pt could form PtH at a lower pressure than the bulk Pt due to its high specific surface and structure defects.The present work provides the possible route to new metal hydrides under mild conditions.  相似文献   
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高压科学是研究不同压力条件下物质的结构、状态、理化性质及变化规律的学科。在高压科学研究中,多以凝聚态物质为研究对象,涉及的领域也非常广泛,包括物理学、化学、材料学、地质学、生物学、航天学等等,是一门以实验为基础的学科。高压科学之所以能成为一门独立的学科,还因为高压研究需要使用特殊且精巧的技术和方法来实现,是以技术创新为牵引的科学研究领域。而今,各种实验测试手段已经可以成熟地运用在该学科中,比较常见的有:高压拉曼散射、高压红外光谱、高压布里渊散射、高压同步辐射XRD、高压电学测量以及高压磁学测量等诸多技术。文章系统介绍了以上高压原位实验测试方法的原理、发展、作用及应用,有助于读者对原位高压测试技术有更深刻的认识和理解,为更高压力下的原位高压探测技术的发展提供重要的基础和借鉴。  相似文献   
3.
The structural stability and electrical properties of A1B2-type MnB2 were studied based on high pressure angle- dispersive x-ray diffraction, in situ electrical resistivity measured in a diamond anvil cell (DAC) and first-principles calcu- lations under high pressure. The x-ray diffraction results show that the structure of A1B2-type MnB2 remains stable up to 42.6 GPa. From the equation of state of MnB2, we obtained a bulk modulus value of 169.9~3.7 GPa with a fixed pressure derivative of 4, which indicates that A1B2-type MnB2 is a hard and incompressible material. The electrical resistance un- dergoes a transition at about 19.3 GPa, which can be explained by a transition of manganese 3d electrons from localization to delocalization under high pressure.  相似文献   
4.
The incomplete decomposition product of metastable hydrazine(N2H4)instead of the energetically favorable ammonia(NH3)upon decompression is one drawback in applications of energetic material oligomeric hydronitrogens.We explore the stability of hydrazine molecules in hydrazine hydrate(N2H4 H2O)under pressure in diamond anvil cells(DACs)combined with in situ Raman spectroscopy and synchrotron x-ray diffraction(XRD)measurements.The results show that one NH2 branch forms NH3 group by hydrogen bonds between hydrazine and water molecules after the sample crystallizes at 3.2 GPa.The strengthening hydrogen bonds cause the torsion of hydrazine molecules and further dominate a phase transition at 7.2 GPa.Surprisingly,the NN single bonds are strengthened with increasing pressure,which keeps the hydrazine molecules stable up to the ultimate pressure of 36 GPa.Furthermore,the main diffraction patterns show continuous shift to higher degrees in the whole pressure range while some weak lines disappear above 8.2 GPa.The present peak-indexing results of the diffraction patterns with Materials Studio show that the phase transition occurs in the same monoclinic crystal system.Upon decompression,all of the hydrazine molecules extract from hydrazine hydrate crystal at 2.3 GPa,which may provide a new way to purify hydrazine from hydrate.  相似文献   
5.
The structural stability and electrical properties of AlB2-type MnB2 were studied based on high pressure angledispersive x-ray diffraction, in situ electrical resistivity measured in a diamond anvil cell(DAC) and first-principles calculations under high pressure. The x-ray diffraction results show that the structure of AlB2-type MnB2 remains stable up to 42.6 GPa. From the equation of state of MnB2, we obtained a bulk modulus value of 169.9±3.7 GPa with a fixed pressure derivative of 4, which indicates that AlB2-type MnB2 is a hard and incompressible material. The electrical resistance undergoes a transition at about 19.3 GPa, which can be explained by a transition of manganese 3d electrons from localization to delocalization under high pressure.  相似文献   
6.
Simple molecular solids have been an important subject in condensed matter physics,particularly for research of pressure-induced molecular dissociation.We re-explore the structural changes of element bromine through pressure-induced decomposition of solid HBr.The phase changes in HBr are investigated by Raman spectroscopy and synchrotron x-ray diffraction up to 125 GPa at room temperature.By applying pressure,HBr decomposes into solid bromine in the pressure range of 18.7-38 GPa.The solid bromine changes from molecular phase to incommensurate phase at 81 GPa,and finally to monatomic phase at 91 GPa.During the process of pressureinduced molecular dissociation, the intermediate incommensurate phase of element bromine is confirmed for the first time from the x-ray diffraction studies.The decomposition of HBr is irreversible since HBr cannot form again upon pressure decompression.  相似文献   
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