Mn3Zn0.8Ni0.2N的高压同步辐射研究

 利用金刚石对顶压砧,对钙钛矿型金属锰化物Mn₃Zn_0.8Ni_0.2N进行了原位高压同步辐射角散X射线衍射研究。研究表明,在0~29.9 GPa的压力区间内,样品没有发生结构相变,因而在该压力下样品的物性变化并非由结构相变所导致。卸压以后,样品的特征峰都回到了初始位置。通过Birch-Murnaghan方程,拟合得到了样品的体弹模量为86.5 GPa。     

层状钙钛矿结构锰氧化物Ca3Mn2O7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Ca     

Al70Co15Tb5Ni10合金中准晶相关相的高压研究

 使用静高压熔态淬火方法，在Al₇₀Co₁₅Tb₅Ni₁₀合金中截获到迄今为止晶胞参数最大的两个十次准晶的Penrose-Tiling相关相。其晶胞参数分别为：简单正交晶体a=6.11 nm，b=0.4 nm，c=8.4 nm；底心正交晶体a=6.11 nm，b=0.4 nm，c=8.4 nm。其晶体结构和晶胞参数与目前理论上的预言基本吻合。     

高压截获十次准晶相关晶体相和纳米级超微粒

 对Al₇₀Co₁₅Ni₁₀Tb₅合金进行了静高压（7.0 GPa）熔态（1 700 ℃）淬火（冷却速率10²⁰ C/s）处理，首次观察到一个新十次准晶相关晶体相。该相属底心正交晶体，晶胞参数为a=2.28 nm、b＝1.60 nm、c＝5.46 nm。通过高分辨像分析，给出了它的二维点阵模型。同时在样品中发现了尺寸均匀的纳米级非晶超微粒形成，超微粒为球形，直径30~40 nm。     

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.     

Effect of Annealing on Ferroelectric Properties of Nanometre BaTiO3 Ceramics Prepared by High Pressure Sintering Method

Dense nanocrystalline BaTiO3 ceramics with a grain size of 5Onto are prepared under 6 GPa at 1273K using a high pressure sintering method. The sintered bulk is uniform and the relative density is above 97%. We anneal the ceramic samples in oxygen with various temperatures and for the annealing, several broadened peaks can be observed at different times without apparent grain growth. After about 378K（ by dielectric measurements. However, these peaks are very different from those of coarser-grained ceramics. It is indicated that both the elimination of oxygen vacancies and the release of residual stresses caused by high pressure greatly improve the overall ferroelectric properties of BaTiO3 ceramics. The observation of nearly linear polarization hysteresis loop after anneal provides the solid evidence of ferroelectricity in these nano-sized BaTiO3 ceramics. It is believed that the absence of 90° domains and the existence of poor-permittivity nonferroelectric grain boundaries contribute to the slim loop.     

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.     

铁基结合剂金刚石节块性能的优化

以性能较好的铁基结合剂为基体,加入表面未镀、镀Ni和纳米Al2O3/Ni复合镀层的金刚石,用热压烧结的方法得到铁基结合剂金刚石节块,测量了金刚石铁基结合剂节块的抗弯强度和耐磨性,采用SEM和EDS对复合镀层和金刚石表面的形貌和组分进行了表征.结果表明:在金刚石表面镀覆纳米Al2O3/Ni层后,复合镀层均匀致密,晶粒细小;在热压烧结中,复合镀层能阻止金刚石的石墨化,使金刚石和基体之间有强的化学结合,所以金刚石和铁基结合剂之间的界面结合紧密,结合剂对金刚石的把持力提高,节块的抗弯强度从468.9 MPa增加到563.8 MPa,磨耗比从349升高到700.