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.     

Al70Co15Tb5Ni10合金中准晶T相和相关相的形成

 对Al₇₀Co₁₅Tb₅Ni₁₀合金进行了静高压（4.40 GPa）熔态（1 450 ℃）淬火（冷却速率为10² ℃/s）研究。首次在该系统中观察到准晶T相和一个新的十次准晶相关相形成。使用透射电镜对准晶相和准晶相关相进行了结构分析，得到了准晶相关相的晶胞参数。使用已有的理论模型对该相关相的形成进行了讨论。     

高压下Al0.77Mn0.19Yb0.04合金准晶T相形成及结构

 利用静高压（4.2 GPa）熔态（1 300 ℃）淬火（10² ℃/s）方法，对含稀土的铝锰合金Al_0.77Mn_0.19Yb_0.04进行了研究。首次发现了准晶T相得形成。利用选区透射电子衍射技术，对合金中准静态的结构对称性进行了观察和分析。根据X射线和电子衍射对其衍射峰进行了指标化。使用扫描电镜和能谱技术进行了成份分析。     

Misfit-layered compound PbTiS3 with incommensurate modulation： Transmission electron microscopy analysis and transport properties

The microstructural characteristic of the misfit-layered compound PbTiS3 has been studied with transmission electron microscopy. All the incommensurate modulation-induced satellite spots and main diffraction spots of basic sublattices can be indexed systematically with a superspace group method. Finally, the relationship between the electronic transport properties and the crystal structure is discussed.     

Superconductivity in Topological Semimetal θ-TaN at High Pressure

Recently,θ-TaN was proposed to be a topological semimetal with a new type of triply degenerate nodal points.Here,we report studies of pressure dependence of transport,Raman spectroscopy and synchrotron x-ray diffraction on θ-TaN up to 61 GPa.We find that θ-TaN becomes superconductive above 24.6 GPa with T_c at 3.1 K.The θ-TaN is of n-type carrier nature with carrier density about 1.1 × 10~(20)/cm~3 at 1.2 GPa and 20 K, while the carrier density increases with the pressure and saturates at about 40 GPa in the measured range.However,there is no crystal structure transition with pressure up to 39 GPa,suggesting the topological nature of the pressure induced superconductivity.     

高压下Sr2FeMoxNb1-xO6 (x=0, 0.3)的电学性质和结构稳定性

 采用金刚石压砧高压装置，研究了双钙态矿结构化合物Sr₂FeNbO₆及其掺杂物Sr₂FeMo_0.3Nb_0.7O₆在室温下，20 GPa内电阻和电容随压力的变化，并发现Sr₂FeNbO₆在7.5 GPa左右压力下发生了相变，而Sr₂FeMo_0.3Nb_0.7O₆的相变发生在2.8 GPa左右。并结合这两个样品的高压下的同步辐射能散X射线衍射实验，进一步证明了这两种相变是电子结构相变引起的。     

层状钙钛矿结构锰氧化物Ca3Mn2O 7的压致结构相变

采用金刚石压砧高压装置（DAC）,对层状钙钛矿结构锰氧化物Ca3Mn2O7的粉末样品进行了高压能散X射线衍射实验。实验结果表明,在0－35GPa压力范围内,Ca3Mn2O7晶体结构发生了两次相变。在1．3GPa左右,由原来的四方相转变为正交相,在9．5GPa左右,又由正交相向新的四方相转变。     

静高压熔态淬火Al70Co15Ni10Tb5合金中十次准晶的相关晶体相C4和C5

 使用静高压熔态淬火方法，在Al₇₀Co₁₅Ni₁₀Tb₅合金中截获到两个新的十次准晶相关相C₄和C₅。其晶胞参数分别为：底心正交晶体（C₄），α=1.38 nm，b=1.60 nm，c=2.0 nm；简单正交晶体（C₅），α=1.20 nm，b=1.60 nm，c=2.30 mn。对二者的高分辨象进行了分析和研究，发现他们有着密切的关系，且可以认为是Penros拼图有序化的结果。     

Pressure-induced phase transitions in single-crystalline Cu4Bi4S9 nanoribbons

In situ angle dispersive synchrotron X-ray diffraction and Raman scattering measurements under pressure are em- ployed to study the structural evolution of Cu4Bi4S9 nanoribbons, which are fabricated by using a facile solvothermal method. Both experiments show that a structural phase transition occurs near 14.5 GPa, and there is a pressure-induced re- versible amorphization at about 25.6 GPa. The electrical transport property of a single Cu4Bi4S9 nanoribbon under different pressures is also investigated.     

纳米材料及HfO_2基存储器件的原位电子显微学研究

总结了我们将原位技术和透射电子显微学分析方法相结合,针对纳米材料和器件的结构、形貌、成分以及电势分布等物理性质的动态行为所开展的综合物性表征和分析工作.主要成果有:揭示了C_(60)纳米晶须在焦耳热作用下的结构相变路径;观察到了电荷俘获存储器中的电荷存储位置以及栅极电压诱导的氧空位缺陷;研究了阻变存储器中氧空位通道的形成过程以及导电通道的开关机理.这些成果不但有助于深入理解纳米材料和器件相关功能的物理机理,改善其工作性能,更展示了透射电子显微学在微电子领域强大的研究能力.