含镧金属富勒烯不同溶剂的高温高压提取

将金属原子或离子置于以Ｃ６０、Ｃ８２为代表的富勒烯笼内形成金属富勒烯包合物是目前富勒烯研究的热点课题［１～３］．合成的金属富勒烯常伴随生成较难分离的空心富勒烯,传统的索氏提取法效率又较低,使得金属富勒烯的深入研究受到限制［１,２］．本文采用改进的高温...     

Structure and Luminescence Characteristics of Europium Activated Strontium Silicates Sr（Eu ,Bi）SiO3 and Sr（Eu ,Bi）2SiO4

Sr2SiO4 ： Eu^3 , Bi^3 and SrSiO3 ：Eu^3 , Bi^3 samples were synthesized at high temperature and high pressure. The effect of high pressure on the structure and luminescence properties of the samples were stud-ied. As a comparison, the samples were also prepared by the method of sol-gel at high temperature and atmo-spheric pressure. The SrSiO3 ： Eu^3 , Bi^3 prepared at atmosphere has a hexagonal phase structure; in the pressure range of 2. 34—4. 10 GPa, it is transformed into a pseudo-orthorhombic structure (monoclinic), and in the pressure range of 4. 10—4. 15 GPa, the structure change of Sr2SiO4 ： Eu^3 , Bi^3 has not been ob-served, it maintains the monoclinic structure of the samples synthesized at an atmospheric pressure. High pressure makes the luminescence properties of the samples changed obviously. The intensity and the relative quantum luminescent efficiency decrease, the half-width increases obviously and the red shift occurs. The changes of the luminescence properties result from the pressure-induced changes of the crystal structures.     

高温高压合成的Ce1-xEuxO2-δ固溶体的价态和输运性质研究

Ce O2 具有典型的萤石结构 ,当晶格中产生氧缺位时则形成氧离子固体电解质材料 Ce O2 -δ.Ce O2中的氧缺位浓度可通过掺入不同价态的离子来调整 ,如通过掺杂 Ca,Sr,Y或其它稀土离子所形成的固溶体具有比 Y稳定的 Zr O2 更高的离子电导率 [1] .近年来通过水热法合成了一些 Ce O2 基固体电解质 [2～ 4 ] ,在对 (Ce O2 ) 1- x(Bi O1.5) x 固溶体的研究中发现 ,Bi2 O3在 Ce O2 中的固溶限可达 5 0 % ,而 Sm2 O3在 Ce O2 中的固溶限仅为 3 0 % .高温高压在化合物的合成方面具有可调节离子价态和阴离子缺位数等特点 .本文利用高温高压…     

高温高压法提取金属富勒烯Lnm@C2nLn=Y,Gd, Tb)

笼内金属富勒烯以其独特的结构性质和潜在的应用价值而引起了人们极大的注意 [1～ 3] ,但因制备技术复杂、产率低以及将其从伴生的空心富勒烯中分离出来比较困难而使其研究受到很大的限制 .笼内金属富勒烯的分离提取始终是金属富勒烯研究的一个重要分支 .通常的方法是将放电得到的烟炱采用甲苯索氏提取的方法粗提 ,然后用高压液相色谱法分离得到纯品 ,笼内金属富勒烯的产率仅为烟炱的 0 .1 % [4～ 6] .我们改进了常规的提取方法 ,建立了一种新的提取方法—高温高压提取法 .具体的做法是采用甲苯索氏提取法从烟炱中提取出空心富勒烯和少量金…     

The synthesis of ZnP4 based on liquid–solid reaction under high pressure and temperature

In this article we reported the successful high pressure and temperature synthesis of micron-sized zinc tetraphosphide (ZnP₄) crystals based on the liquid–solid reaction between Zn and P at a large-volume cubic press. Techniques of X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDXA) were employed to investigate the phase structure, grain size, morphology and stoichiometric ratio of crystals. The results indicate that the synthesized ZnP₄ has a tetragonal structure with the space group of P41212, and the grains with size of about 50 μm can be prepared at 4.0 GPa and 1000 °C. We also obtained the pressure–temperature (P–T) formation region of ZnP₄ and discussed the formative mechanism of ZnP₄ crystals.     

密闭式微波降解法促进常见人参皂苷向稀有人参皂苷转化的规律

采用密闭微波技术对7种常见人参皂苷单体(Rb1,Rb2,Rb3,Rc,Rd,Re和Rg1)进行降解,通过高效液相色谱(HPLC)分析并与相同条件下非微波降解物对比,研究了密闭微波降解人参皂苷的产物在化学结构及组成上的变化规律,以期快速、高效地制备生物活性高的稀有人参皂苷.结果表明,密闭式微波降解法能够使常见人参皂苷基本降解完全,而相同条件下非微波降解法则基本不发生降解.原人参二醇型人参皂苷易水解掉C20位糖,并发生C20位构型变化,生成20(R)-Rg3和20(S)-Rg3,其中20-(R)为优势构型,C20位羟基进一步脱水产生稀有人参皂苷Rk1和Rg5.同时,20(S/R)-Rg3失去C3位的1分子葡萄糖转化为20(S/R)-Rh2,C20位羟基再进一步脱水生成了Rk2和Rh3.此外,人参皂苷C20位所连的糖种类与构型影响了降解产物中各稀有皂苷的组成与比例,但7种原人参二醇型人参皂苷密闭式微波降解产物中Rg5含量均为最高.密闭式微波降解对原三醇型人参皂苷的转化作用与原二醇型人参皂苷具有相似的规律,人参皂苷Re和Rg1的密闭式微波降解产物中Rh4含量均为最高.本文结果进一步说明在相同的降解条件下,密闭式微波降解法的降解效率远高于高温高压非微波降解法,密闭式微波降解可明显促进常见人参皂苷向稀有人参皂苷转化,因此采用密闭微波技术对常见人参皂苷进行降解可以大量获得稀有人参皂苷.     

Synthesis of boron suboxide (B6O) with ball milled boron oxide (B2O3) under lower pressure and temperature

Boron reacted with ball milled boron oxide under pressures between 1 and 5 GPa and at temperatures between 1300 and 1700 °C to afford boron suboxide (B₆O). Icosahedral B₆O grains with diameters ranging from 100 nm to 1.3 μm were prepared. The factors that affect the synthesis of B₆O are investigated. The best sample with crystal size up to 1.3 μm is obtained at 2 GPa and 1400 °C for 6 h. The indentation experiment gave an average Vickers hardness of 32.3 GPa for bulk B₆O sample, which is consistent with previous reports. Bulk B₆O sample exhibits oxidation resistance in air up to 1000 °C and mild oxidation in the temperatures of 1000-1200 °C, which is more oxidation resistant than diamond. It is possible that B₆O could be used as a substitute for diamond in industry because of its relatively mild synthesis conditions, high thermal stability and high hardness.     

单相Ce0.5Zr0.5O2立方固溶体的高压高温合成

以化学沉淀法制备的 Ce O2 和 Zr O2 纳米微粒为前驱体 ,首次在高压高温 (3 .1 GPa,1 0 73 K)下合成了单相 Ce0 .5Zr0 .5O2 面心立方固溶体 .使用 X射线衍射、TG-DTA、XPS、Raman、电子自旋共振谱和交流阻抗谱等对样品的结构、Ce离子的价态和导电性进行了表征 .实验结果表明 ,纳米 Ce O2 -50 % Zr O2 混合物在高压 (0 .9GPa以上 )高温 (1 0 73 K以上 )条件下可以发生固态反应 ,高压下固溶温度明显降低 .Ce0 .5Zr0 .5O2 面心立方固溶体在 773 K以下是热稳定的 ,不发生结构转变 ,固溶体中 Ce离子完全以 Ce4 + 形式存在 ,773 K退火也不引起 Ce4 + 向 Ce3 + 转变 ,晶格中氧缺位非常少 .Ce0 .5Zr0 .5O2 面心立方固溶体是离子导电 ,82 3 K时电导率 σ=1 .2× 1 0 -5S/cm,与纯 Ce O2 在同温度下的电导率同数量级 ;1 1 2 3 K时 σ=2 .1× 1 0 -3 S/cm,小于掺入稀土或碱土氧化物的氧化锆和氧化铈基电解质的电导率 .在高温区和低温区 ln(σT)与 1 /T的关系满足斜率不同的二条直线 ,低温活化能小于高温活化能 .固溶体的显微硬度 (50 g载荷 )为 572 HV.     

稀土对ZA-27合金高温性能的影响

研究了ｃＣｅ≥４５％（ｗｔ）的混合稀土对ＺＡ－２７合金显微组织及高温机械性能的影响。结果表明，在锌铝合金中，稀土元素可与Ａｌ、Ｚｎ、Ｃｕ等形成多种复杂成分化合物，其硬度高，热硬性好，分散于晶界或枝晶间，细化了组织，且有效地阻碍了高温时基体的变形和晶界移动。添加适量的稀土，可使ＺＡ－２７合金在１５０℃时的抗拉强度提高３０％，硬度提高２５％，延伸率虽有所下降，但冲击韧性却得以改善。同时发现，室温强度变化不大，唯塑性、韧性略有下降。     

（Sr，Ba）_（1－x）Eu_xTiO_3的高温高压合成及XPS研究

用高温高压法合成了Ｓｒ１－ｘＥｕｘＴｉＯ３（ｘ＝０．０，０．１，０．２，０．３，０．４，０．５）及Ｂａ０．３Ｅｕ０．７ＴｉＯ３化合物．结果表明，所有样品均为立方结构，样品中存在Ｅｕ（Ⅱ）和Ｅｕ（Ⅲ）的混合价．Ｅｕ３＋的掺入直接影响了Ｓｒ离子与氧离子的结合，使Ｓｒ３ｐ３／２的结合能随ｘ的增加而增加．     

A New Method of Measurement for Elastic Wave Velocities in Minerals and Rocks at High Temperature and High Pressure and Its Significance

We developed a new method of measurement for elastic wave velocity of rocks and minerals at high temperature and high pressure in a wedge-type cubic anvil. The shear-wave and other ultrasonic wave can be identified by full wave phase analysis (FWPA), thus the velocities of compression-wave and shear-wave can be obtained in a single experiment. We have done the measurements of elastic wave velocities on pyrophyllite, etc. at high pressure (0.1—5.5 GPa) and high temperature (ambient temperature 1600℃), the ranges of the pressure and the temperature are in the head among the methods of the wave velocites measurement in laboratory in the world.     

Thermoelectric properties of HPHT sintered In-doped Pb0.5Sn0.5Te

The thermoelectric properties of Pb_0.5Sn_0.5Te doped with In at 1.0, 2.0, and 3.0×10¹⁹/cm³ and sintered at a high pressure and high temperature (HPHT) of 4.0 GPa and 800 or 900 °C, respectively, have been studied. All samples show p-type semiconducting behavior with positive thermopower. We find that HPHT sintering of conventionally synthesized materials improves their thermoelectric properties. The highest power factor is obtained for In doping of 2.0×10¹⁹/cm³ with 13.5 μW/cm K² at 230 °C. The corresponding figure of merit is 1.43×10⁻³/K. This represents a twofold improvement in thermoelectric figure of merit, compared to the conventionally sintered materials reported in the literature. When exposed to 400 °C for 10 days, samples sintered at 900 °C exhibit more stable thermoelectric properties, while the properties of those sintered at 800 °C deteriorated. These results demonstrate that HPHT sintering is a viable and controllable way of tuning the thermoelectric properties of PbTe-based materials.     

毫秒激光烧蚀镍靶高效率制备NiO纳米立方体

利用长脉宽毫秒激光烧蚀浸没在循环水中的金属镍靶制备了大量的氧化镍(NiO)纳米立方体, 通过透射电子显微镜(TEM)、 选区电子衍射(SAED)、 X射线衍射(XRD)和能量色散谱(EDS)等手段表征了产物的形貌和结构. 结果表明, 高功率密度激光产生的高温高压条件是形成NiO纳米立方体的最重要因素. 激光功率密度高于10⁴ W/cm²时可以生成NiO纳米立方体, 当功率高于该阈值时激光首先将镍靶烧蚀为金属液滴, 高温的金属液体加热周围液体, 并由于液体的限制效应使得压力进一步升高, 最后金属液滴与液体发生表面反应生成NiO纳米立方体.     

Sb2O4 at high pressures and high temperatures

Investigations on Sb₂O₄ at high pressure and temperature have been performed up to 600 °C and up to 27.3 GPa. The so-called “high temperature” phase (β-Sb₂O₄) was obtained following pressure increase at ambient temperature and at relatively low temperatures. Thus, in contrast to previous perceptions, β-Sb₂O₄ is the modification more stable at high pressures, i.e., at low temperatures. The fact that the metastable α-form is typically obtained through the conventional way of preparation has to be attributed to kinetic effects. The pressure-induced phase transitions have been monitored by in-situ X-ray diffraction in a diamond anvil cell, and confirmed ex-situ, by X-ray diffraction at ambient conditions, following temperature decrease and decompression in large volume devices. Bulk modulus values have been derived from the pressure-induced volume changes at room temperature, and are 143 GPa for α-Sb₂O₄ and 105 GPa for the β-Sb₂O₄.     

铂—稀土合金的高温氧化与挥发

研究了铂和铂－稀土合金在７００－１４００℃相对静止空气中的氧化与挥发，其动力学曲线不仅符合Ｆｉｃｋ定律，而且与Ｊ－ＭＡ方程吻合较好，在１１００℃以上Ｐｔ的挥发很大，添加 土元素后大大改善了Ｐｔ的抗氧化能力，Ｐｔ的挥发主要取决于表面扩散，而Ｐｔ－ＲＥ合金的氧化受控于晶界扩散。