Structural Stability of CaCuMn6O12 under High Pressure and Low Temperature

In situ high pressure energy-dispersive x-ray synchrotron radiation diffraction and resistance experiments are carried out on CaCuMn6O12. Its crystal structure is stable in the measured pressure range. The equation of state of CaCuMn6O12 is obtained from the V/Vo - P relationship （V and Vo are the volumes at pressure P and at atmosphere）. The bulk modulus Bo is calculated based on the Birch-Murnaghan equation. Low temperature x-ray diffraction shows no phase transition occurring down to 160K.     

Studies on the superconductivity for the “111” type iron arsenide superconductor

The “111” type Li _x FeAs (x ranges from 0.8 to 1.2) with Cu₂Sb type tetragonal structure was synthesized with T _c 18 K. The isostructure NaFeAs was further studied, which shows superconductivity with T _c up to 26 K. The effect of pressure on superconductivity was investigated.     

Superconductivity of Lanthanum Superhydride Investigated Using the Standard Four-Probe Configuration under High Pressures

Recently,the theoretically predicted lanthanum superhydride,LaH_10±δ,with a clathrate-like structure was successfully synthesized and found to exhibit a record high superconducting transition temperature T_c≈250 K at～170 GPa,opening a new route for room-temperature superconductivity.However,since in situ experiments at megabar pressures are very challenging,few groups have reported the ～250 K superconducting transition in LaH_10±δ.Here,we establish a simpler sample-...     

Metallization of Cu3N Semiconductor under High Pressure

Using the four-probe method, we investigate the electrical conductivity of Cu3N under high pressure with the diamond anvil cell. Cu3N is a semiconductor at ambient pressure showing a band gap about l eV. With the application of quasi-hydrostatic pressures, its resistance decreases dramatically over five orders of magnitude from ambient to 9 GPa. The compound became a metal at pressure about 5.5 GPa, which is in well agreement with the recent first principle calculation.     

How to detect melting in laser heating diamond anvil cell

Research on the melting phenomenon is the most challenging work in the high pressure/temperature field. Until now,large discrepancies still exist in the melting curve of iron, the most interesting and extensively studied element in geoscience research. Here we present a summary about techniques detecting melting in the laser heating diamond anvil cell.     

新型带宽调制型Mott化合物的高压合成及其金属化相变

利用高温高压条件，制备了（SrCa）CrO3系列带宽可调型的钙钛矿Mort化合物。在10 GPa的外加压力下，观察到SrCrO3的绝缘体-金属化相变。原位高压x射线衍射实验表明，Sr／CaCrO3晶体结构在0-9 GPa压力范围内保持稳定。但SrCrO3在4 GPa时存在着电子结构变化所引起的等结构相变，表现为体弹性模量的反常软化。此外，由于电子关联效应，磁性和热输运性质的测试结果表明了材料的奇异电子态特征。     

Site-Selective Magnetic Moment Collapse in Compressed Fe5O6

Iron oxide is one of the most important components in the Earth’s mantle.The recent discovery of the stable presence of Fe₅O₆ in the Earth’s mantle environment has stimulated significant interests in understanding of this new category of iron oxides.We report the electronic structure and magnetic properties of Fe₅O₆ calculated by the density functional theory plus dynamic mean field theory(DFT+DMFT) approach.Our calculations indicate that Fe₅     

Structure-Spin-Transport Anomaly in Quasi-One-Dimensional Ba_9Fe_3Te_(15) under High Pressure

Recently, a series of novel compounds Ba₃MX₅(M = Fe, Ti, V; X = Se, Te) with hexagonal crystal structures composed of quasi-1-dimensional(1D) magnetic chains has been synthesized by our research team using high-pressure and high-temperature methods. The initial hexagonal phases persist to the maximum achievable pressure, while spin configurations and magnetic interactions may change dramatically as a result of considerable reductions in interchain separations upon pressuriz...     

压力诱导酌拓扑绝缘体化合物Bi2Te3常压相的超导性

通过高压电阻测量,发现了拓扑绝缘体化合物BizTe3压力诱导的超导性,在3-6GPa的压力范围内,超导临界温度L约为3K．高压下原位同步辐射的结果证明这个超导相来源于常压相结构．通过霍尔效应的测量,发现超导的Bi2Te3样品的载流子为P型．对高压同步辐射结果Reitveld精修得到的晶格参数和原子位置,并以此进行第一性...     

Isostructural Phase Transition of TiN under High Pressure

In situ high-pressure energy dispersive x-ray diffraction experiments on polycrystalline powder TiN with NaCltype structure have been conducted with the pressure up to 30.1 GPa by using a diamond anvil cell instrument with synchrotron radiation at room temperature. The experimental results suggest that an isostructural phase transition might exist at about 7 GPa as revealed by the discontinuity of V/Vo with pressure.