巴丹吉林沙漠东缘不同粒级砂土空间分布的多重分形研究

为了探讨不同粒级砂土(细砂,中砂,粗砂)空间变化的特点,引入多重分形理论,揭示粒级砂土随着土层深度空间变化情况.针对土壤属性做了空间变异性分析,利用Pearson相关系数考察了不同深度下粒级砂土分布密度之间的关系,进一步做了多重分形特征判断,表明不同粒级砂土空间分布存在多重分形的变化特征.又利用广义分形谱探讨了相应的多重分形特点.多重分形谱表明,不同土层深度下,粒级砂土空间变异性增强,同时密度空间分布的变异性依赖高密度分布区的程度增强.     

Preparation of Thermo-Stable Bulk Metallic Glass of Nd10Cu20Ni10Al10 by Rapid Compression

Melt of Nd60Cu20NiloAl10 alloy is solidified by rapid compression from 0.1 to 5.5 GPa at 793K and from 0.1 to 3.2GPa at 873K within 20ms, separately. A fully bulk metallic glass is obtained by the rapid compression method. By comparing with as-cast bulk metallic glass （BMG）, it is found that Nd60Cu20Ni10Al10 BMG prepared by rapid compression exhibits a higher thermodynamic stability and a paramagnetic property. The relationship between the glass-formation temperature and the pressure in rapid compression for the BMG is demonstrated in the P - T phase diagram.     

Preparation of High-Density Nanocrystalline Bulk Selenium by Rapid Compressing of Melt

The melt＇s solidification behavior of elemental selenium is investigated by a series of experiments including rapid compressing to 2.8 and 3.5 GPa within 20ms respectively, slow compressing to 2.8 GPa for 20 min and natural cooling at ambient pressure. Based on the x-ray diffraction, scanning electron microscope and transmission electron microscope results of the recovered samples, it is clearly shown that homogenous nanostructures are formed only by the rapid compression processes, and that the average crystal sizes are about 18.7 and 19.0 nm in the samples recovered from 2.8 and 3.5 GPa, respectively. The relative density of the nanocrystalline bulk reaches 98.17% of the theoretical value. It is suggested that rapid compression could induce pervasive nucleation and restrain grain growth during the solidification, which is related to fast supercooling, higher viscosity of the melt and lower diffusivity of atoms under high pressure.     

滑块式六含八超高压实验装置及其压力温度标定

报道了一种新型六含八超高压实验装置.三柱式的机体框架与滑块式上三下三模具同为三次对称结构,在力学上较为合理.该装置加压时具有自动校准位置能力,同步性和重复性好.模具推动八块硬质合金压砧在叶腊石八面体中产生高压.分别采用Bi丝和ZnTe晶体的压致相变点255,77,96,12 GPa,对截角边长8 mm压砧和125 mm边长叶腊石块组合的实验体系进行了室温下的压力标定,结果表明压力可达12 GPa以上.在10 GPa压力下,用WRe3-WRe25热电偶将温度标定到1560 ℃,并结合铁碳二元相图和钢 关键词： 压力标定 温度标定 六含八多压砧模具 高压装置     

高温高压合成新型量子功能材料

<正>元素周期表中从IIIB族到VIII族的化学元素称为过渡元素,其价电子依次填充在次外层的d轨道上。以过渡族金属氧化物为代表的强关联电子体系是过去三十多年间凝聚态物理研究的焦点内容。由于在这些体系中存在电荷、自旋、轨道和晶格等量子自由度的相互耦合和竞争,会造成一系列丰富奇特的物理现象和效应。例如,层状铜氧化体系中发现的高温超导电性;钙钛矿锰氧化物(例如La_(1-x)Ca_xMnO_3)的电阻率在磁场中出现了     

Bridgman压砧几种内加热方式及其温度测量

 设计了4种Bridgman压砧内加热方式，尝试了钽和石墨作为加热材料，采用双热电偶测温，分别测量了不同加热方式的样品中部和上部温度与输入电压的关系，并粗略地讨论了样品的温度梯度。在0.1 GPa压力下，样品温度达到1 300 ℃以上。另外，在5.0 GPa高压下、1 000 ℃范围内测量了样品温度随输入电压变化的曲线。