锡青铜基自润滑材料的摩擦学特性研究

采用粉末冶金自由烧结工艺制备出锡青铜基自润滑复合材料,对该类复合材料的力学性能与摩擦磨损特性进行了研究,从固体润滑剂角度就其室温与450℃自润滑机理进行了分析与探讨。研究结果表明,该类材料在室温至450℃温度范围内具有良好的机械性能与磨擦磨损特性。XRD分析结果显示：在室温下磨损表面形成的含石墨、Pb和SnO2的复合膜是其具有润滑性能的主要原因;在高温下则由石墨、Pb2O3和CuO组成的复合膜起主要润滑作用。     

Synthesis, structure and ferroelectric property of a new niobate: Sr6CrNb9O30

A new niobate Sr₆CrNb₉O₃₀ was found in the ternary system SrO---Cr₂O₃---Nb₂O₅. The transparent crystal which has a green color and a need-like shape can be grown by the flux method. The crystal structure was determined by x-ray diffraction analysis and dielectric measurement, and it belongs to the orthorhombic tungsten bronze structure at room temperature with space group Cmm2, and unit cell parameters A=1.7505(4) nm, B=1.7510(1) nm, C=7.768(4)nm, Z=4. Dielectric constant measurement show that Sr₆CrNb₉O₃₀ has two phase transitions, paraelectric to ferroelectric at 110°C and ferroelectric to ferroelastic at 205°C.     

蓝青铜单晶Rb_(0.3)MoO_3和Rb_(0.15)K_(0.15)MoO_3的热电势特性

在 90～ 2 90 K范围内对蓝青铜单晶 Rb0 .3 Mo O3和 Rb0 .1 5 K0 .1 5 Mo O3的热电势与温度的关系进行了比较研究 ,发现 :1)在 180 K附近 ,两种蓝青铜导体的热电势出现突变是这两种物质存在 Peierls相变的的又一例证并分别分析了 A位元素的完全替代和部分替代对 Peierls相变的影响 ;2 )在相变点 TP以上和以下 ,两者的热电势有相似的变化 ,由高温区较小的正值变为低温区较大的负值 ,并可以用经验关系式 S=AT B/ T来描述     

长江中游地区战国青铜箭镞的锈蚀形态

利用扫描电子显微镜（SEM）、能谱仪（EDS）、显微硬度等分析测试技术从材料科学和物理学的角度对长江中游地区战国晚期占楚墓中出土地的青铜箭镞的锈蚀现象进行了较为全面的研究和分析．发现由于锈蚀程度不同,青铜箭镞的组织结构可分为完全矿化层、过渡层和心部原始材料等3个特征层,其中主要成分为氧化物的完全矿化层的结构最疏松,硬度最低;另外,由于埋藏环境的不同,不同地区的锈蚀分层又有差异．实验还对两种类型的开裂裂纹进行了分析,认为一种裂纹是由矿化层氧化物膨胀引起的剥离开裂,进一步发展形成所谓的“粉状锈”;另一种裂纹是当圆柱形箭镞杆膨胀时,矿化层的塑性差,抗变形能力低而产生的开裂．     

欧式向下敲出看涨幂期权的Esscher变换定价

首先根据障碍期权的不同类型,对普通欧式向下敲出看涨幂期权、部分时间开始、部分时间结束、一般部分时间欧式向下敲出看涨幂期权给出定义.通过E sscher变换分别给出定价公式.另外,对两资产欧式向下敲出幂期权也给出了定价公式,为实践者提供了理论上的参考价格.最后,阐述了此方法的优点.     

泥炭,软褐煤中的芳香烃的荧光特性

对滇西镇安盆地泥炭、软褐煤氯仿沥青“Ａ”中的芳香烃进行了较详细的荧光光度术研究。在蓝光激发下，初始态芳香烃发绿色荧光，接着迅速转变为黄色，进而转变为橙黄色或黄橙色，其Ⅰ_（５４６）很大，介于１２．５０─６０．２０之间，远大于泥炭、软褐煤中的稳定组分的相应值。Ⅰ_（５４６）呈快速负变化；初始态芳香烃荧光光谱为单峰状，λ_（ｍａｘ）为５１０─５４５ｎｍ，总体在５２０─２５ｎｍ，Ｑ_（６５０／５００）为０．３５─１．０６，总体为０．４５─０．５５。随激发时间增长，光谱变为双峰状，λ_（ｍａｘ）及Ｑ_（６５０／５００）均随激发时间增长而出现先增大后减小的变化趋势。     

Highly Stable Aqueous Zinc‐Ion Storage Using a Layered Calcium Vanadium Oxide Bronze Cathode

Cost‐effective aqueous rechargeable batteries are attractive alternatives to non‐aqueous cells for stationary grid energy storage. Among different aqueous cells, zinc‐ion batteries (ZIBs), based on Zn²⁺ intercalation chemistry, stand out as they can employ high‐capacity Zn metal as the anode material. Herein, we report a layered calcium vanadium oxide bronze as the cathode material for aqueous Zn batteries. For the storage of the Zn²⁺ ions in the aqueous electrolyte, we demonstrate that the calcium‐based bronze structure can deliver a high capacity of 340 mA h g^?1 at 0.2 C, good rate capability, and very long cycling life (96 % retention after 3000 cycles at 80 C). Further, we investigate the Zn²⁺ storage mechanism, and the corresponding electrochemical kinetics in this bronze cathode. Finally, we show that our Zn cell delivers an energy density of 267 W h kg^?1 at a power density of 53.4 W kg^?1.     

Low-temperature synthetic route based on the amorphous nature of giant species for preparation of lower valence oxides

We examined low-temperature synthetic route based on the amorphous nature of giant species to succeed to prepare Cs blue bronze (Cs_0.3MoO₃), which has never obtained by usual high-temperature methods, at ca. 680 K. Solid solutions (K_1−xRb_x)_0.28MoO₃ and (Li_1−xNa_x)_0.9Mo₆O₁₇ were also obtained at lower temperatures (ca. 670 K). For the latter system consisting of non-isostructural end members, Li_0.9Mo₆O₁₇-structure type solid solution was formed even when 0.25<x<0.70, unlike the case by the usual high-temperature methods. Metastable mixed oxides Ln₂Mo₃O₉ (Ln=La, Gd) were obtained, but not as single phases.     

硅钨多金属氧酸盐气相扩渗制备钾钨青铜的研究

通过高温固气反应对α-Keggin结构的K4SiW12O40，K6[SiFe(OH2)W11O39]，K7[SiFe3(OH2)3W9O37]和K10[SiMg3(OH2)3W9O37]进行了氯化钕扩渗研究．经X射线能谱(EDS)和X射线光电子能谱(XPS)分析表明氯化钕可渗入到化合物的体相中．X射线粉末衍射(XRD)谱图表明，扩渗后原母体化合物的笼型结构被破坏，WO6八面体重新键合形成四方结构的钾钨青铜化合物K0.57WO3，晶胞参数a=b=1．2302nm，c=0．38355nm．     

介稳态氧化钨超微粉体的水热合成与光致变色性质研究

Under hydrothermal conditions, the superfine powders of cubic pyrochlore-type of tungsten oxide and hexagonal tungsten bronze were obtained by using Na₂WO₄·2H₂O as the starting material. The products were characterized by XRD, TG, IR, UV and EPMA, respectively. The effects of the pH value, the acid concentration, reaction temperature and time on the structure and particle size of products were investigated in detail. The conditions for the preparation of superfine powders of tungsten oxide were optimized. The pH 2.5～4.5 of the reaction system led to the formation of a pyrochlore phase and pH 0.5～2.0 gave the hexagonal tungsten bronze structure. The photochromism property of the hexagonal tungsten bronze was studied. The results show that pyrochlore and bronze phases are decomposed at 300 ℃ and 450 ℃, respectively. With the increasing of temperature, the structure of the two oxides changes. The pyrochlore-type powder changes completely into triclinic Na₂W₄O₁₃ around 500 ℃, while the bronze phase into a mixture of Na₂W₆O₁₉ and triclinic WO₃ at 550 ℃. The powder of the hexagonal tungsten bronze showed better photochromism property.