水热法合成Zn1-xMnxO：Sn和Zn1-x-yMnxCoyO：Cu晶体的磁性

本文采用水热法,以ZnO为前驱物,添加适量的MnCl2·4H2O、SnCl2·2H2O和MnCl2·4H2O、CoCl2·6H2O、CuCl2·2H2O,3 mol/L KOH作矿化剂,430℃反应24 h,分别合成了Zn1-xMnxO:Sn晶体和Zn1-x-yMnxCoyO:Cu晶体.用扫描电镜(SEM)对合成物形貌进行分析,结果表明,Zn1-MnxO:Sn晶体为六棱柱状晶体,直径约为10 μm,较大面积显露正极面c{0001},同时也显露负极面-c{0001}、正锥面p{1011}、负锥面-p{1011}和柱面m{1010}.Zn1-x-yMnxCoyO:Cu晶体也显露负极面-c{0001}、正锥面p{1011}、负锥面-p{1011}和柱面m{1010},{0001}显露面小于{0001}.X射线能谱(EDS)分析表明晶体主要成分为ZnO,Mn2 、Co2 离子掺杂量超过2%;SQUID磁性测量显示所合成晶体在25 K具有反铁磁特征,高温为顺磁性.     

水热合成奇异形态的ZnO晶体

本文采用水热法,以3mol/L KOH为矿化剂,填充度35;,温度430℃,在Zn(OH)2中添加SnCl2·2H2O,添加量为Sn2+:Zn2+=2;条件下,合成出ZnO晶体.产物中除了大量短六棱柱形晶体外,还出现了部分冰激凌形晶体.六棱柱形晶体具有典型的ZnO特征,显露正极面c{0001}、负极面-c{000-1}、柱面m{10-10}、正锥面p{10-11}和负锥面-p{10-1-1}.而冰激凌形晶体有明显的六棱锥晶体外壳,X光能谱(EDS)检测证实晶体各部位的组分均为ZnO.     

碱土金属离子对ZnO极性生长的影响

本文采用水热法,以3mol/L KOH为矿化剂,填充度35%,温度430℃,通过添加适量比例的MgCl2.7H2O和CaO,合成了非极性生长的ZnO晶体。当Mg2 :Zn2 =2%和Ca2 :Zn2 =2~3%时,晶体c轴方向生长速度明显减弱,{0001}方向的极性生长得到控制,所合成的晶体大面积显露正极面 c{0001},同时显露负极面-c{1001-}、正锥面 p{101-1}、负锥面-p{101-1-}和柱面m{101-0}。X光能谱(EDS)没有检测到晶体中含有碱土金属离子。     

In和过渡金属离子共掺杂对ZnO晶体形貌的影响

采用水热法,KOH作矿化剂,在ZnO前驱物中添加适量的CoCl2·6H2O,FeCl2·4 H2O,NiCl2·6H2O,In2O3,其中Co:In:Zn,Fe:In:Zn,Ni:In:Zn 分别为5:1:100,5:1:100,3:1:100.3 mol/L KOH作矿化剂,温度430 ℃,填充度35;,反应24 h,制备了In和过渡族金属离子共掺的ZnO晶体.结果表明,掺杂In2O3时,所合成的过渡族金属离子掺杂的ZnO晶体均呈现六角片状晶体,晶体形貌规则,表面光滑,直径为5～10 μm.和未掺杂In的晶体相比,掺杂In后,晶体c轴极性生长速度得到明显的控制,a、b轴方向生长速度提高,大面积显露+c{0001}、负极面-c{0001}面,另外还显露正锥面+p{1011}、负锥面-p{101-1-}.     

Mn、Cu共掺ZnO磁性的研究

本文采用水热法,分别以ZnO、Zn(OH)2为前驱物,添加一定量的MnCl4.4H2O和CuSO4.2H2O, 3mol/LKOH作矿化剂,温度430℃,填充度35%,反应24h,制备了Mn、Cu共掺ZnO晶体。当前驱物为Zn(OH)2时,所得晶体大部分为短柱状晶体,显露正负极面{0001}、{0001-}、负锥面-p{101-1-}和柱面m{1-010},长度约为30 ～50μm。少部分晶体为单锥六棱柱状,显露正锥面p{101-1},柱面m{1-010},负极面-c{0001-},晶体的长度约为100μm,长径比为5:1。当ZnO用作前驱物时,短柱状晶体长度大约为10 ～30μm,晶体的六棱对称性都出现较大的偏差。X射线荧光能谱分析表明,前驱物为ZnO、Zn(OH)2时,Mn离子含量在分别为3.19%和1.62%原子分数,没有检测到Cu离子。虽然Mn、Cu离子的掺入会明显影响晶体形态,磁性测量显示掺杂Mn、Cu的ZnO仍为反铁磁。     

In掺杂对水热法合成ZnO晶体形貌的影响

本文采用水热法,在ZnO中添加In2O3为前驱物,3mol/L KOH作矿化剂,温度430℃,填充度35;,反应24h,制备了掺In的ZnO晶体.未掺杂In2O3合成的纯ZnO晶体呈六棱锥状,显露负极面-c{0001}、六棱锥面+p{1011}和-p{1011},一般不显露{0001}面.前驱物中掺杂In2O3所合成的ZnO晶体呈六角片状,直径约为5～20 μm,大面积显露{0001}面,另外还显露正锥面+p{1011}、负锥面-p{1011}和负极面-c{0001}.由此可见In掺杂可以明显的改变晶体的形态,使c轴极性快速生长趋向得到明显改善,有利于降低晶体生长缺陷.当采用ZnO晶片为籽晶时,通过水热反应在晶片上生长了一层掺In的ZnO薄膜,通过Hall参数测量得到晶体膜层的电子迁移率约为22cm2/(V·s),载流子浓度约为2×1020 cm-3,具有良好的导电性,同时也说明In可以微量掺入氧化锌晶体.     

Co、Sn共掺杂ZnO晶体的制备及其磁性

采用6 mol/L KOH作为矿化剂,SnO2、CoCl2和ZnO按物质的量比为0.02∶0.5∶1的比例混合作为前驱物,填充度70;,温度430℃,时间24h,采用水热法制备出Co、Sn元素掺杂的ZnO晶体.Sn元素掺杂明显改变了晶体的极性生长特征,较大面积的显露正极面c｛0001｝面,还显露柱面m{l0l0｝、正锥面p{1011｝、负锥面｛1011｝和负极面｛0001｝以及正锥面{1012｝和负锥面{1012｝,晶体长度约为50 μm.经过EDS测量表征,发现制备的ZnO单晶中Co元素的含量达到10.89at;,生成物中出现少量Co氧化物,SQUID测量表明样品主要表现为顺磁性.     

水热法合成Mnx Zn1-xO微晶体

本文采用水热法合成了MnxZn1-xO晶体,水热反应条件为3mol·L-1KOH作为矿化剂,填充度为35;,温度为430℃,在Zn(OH)2中添加一定量的MnO2为前驱物,反应时间为24h.通过X射线能谱仪测量了晶体中的Mn含量,随着前驱物中MnO2含量的增加,晶体中Mn的原子百分比随着增加,Mn最大原子百分比含量超过了2;,晶体的形貌具有纯ZnO晶体的六角柱形特征.显露柱面m{1010}、锥面p{1011}、负极面O面{0001}和正极面{0001}.晶体直径为50～200μm,高度为20～100μm.     

常压化学气相输运法合成Zn1-xCoxO晶体

本文采用高温化学气相输运法,温度970℃,在蓝宝石和石英基片上制备Zn1-xCoxO晶体.电子扫描显微镜(SEM)观察发现,蓝宝石晶片上的晶体形貌较SiO2 晶片上的规整,晶体呈现六棱柱或六棱锥体,一般显露柱面m{101-0}、正锥面p{101-1}、负极面c{0001-}和正极面c{0001},晶体表面光滑.在石英基片上得到的Zn1-xCoxO晶体生长的棱面较模糊,基片的部分晶体非定向密集生长,连续形成薄膜结构.X衍射证实晶体为ZnO纤锌矿结构.X光能谱﹙EDS﹚测量表明 ZnO 晶体有钴离子的存在,且浓度随原料中的Co2O3:ZnO的比值增大而增加 .     

不同矿化剂对水热法生长的ZnO晶体发光的影响

采用水热法,以3 mol/L KOH为矿化剂,填充度35%,温度430℃,前驱物Zn(OH)2,比较研究了三种矿化剂条件下合成晶体的形貌和发光性能。三种矿化剂条件分别为样品1,3 mol/L KOH;样品2,3 mol/L KOH,1 mol/LLiOH;样品3,3 mol/L KOH,CaO∶Zn(OH)2=2%(物质的量百分比)。添加适量比例的LiOH或CaO,合成了非极性生长的ZnO晶体,晶体c轴方向生长速度明显减小,所合成的晶体大面积显露正极面c{0001},同时显露负极面-c{0001}、正锥面p{101}、负锥面-p{10}和柱面m{100}。只添加KOH或辅助添加LiOH时,合成晶体的发光光谱中只有可见光谱,无紫外线带边跃迁发光谱,说明晶体缺陷发光中心较多。添加CaO时合成晶体的发光光谱中有较强的紫外带边跃迁发光,说明晶体缺陷发光中心减少。     

A review of measurement of thermophysical properties of silicon melt

Measurements of thermophysical properties of Si melt and supplementary study of X-ray scattering/diffraction by the authors' group were reviewed. The values obtained differed variously from those of literature. Density was 2–3% larger, surface tension 20–30% smaller, viscosity up to 40% larger, electrical conductivity 8% smaller, spectral emissivity more or less in good agreement with literature values, and thermal diffusivity a few percent larger. An anomalous density jump was found near the melting point. Surface tension and viscosity also showed anomaly. A strange time-dependent change of density was observed over 3 h after melting. X-ray analyses suggested a slight change in local atom ordering, but showed no sign of cluster formation. An addition of 0.1 at% gallium caused the density jump to disappear, while that of boron caused no change. An EXAFS study of the former melt indicated a strong interaction between Ga and Si atoms as if molecules of GaSi₃ existed. The implications of the measured properties are a possibility of soft-turbulence in an Si melt in a relatively large crucible, a more complicated manner of intake of oxygen depleted molten Si from the free surface region to underneath the growing crystal, and a relaxation of the melt after melting arising from trapped gas species.     

原位氮化法制备TiN纳米粉体

用溶胶凝胶法合成的纳米TiO2粉体作为原料,将该粉体在氨气中进行原位氮化制备了TiN纳米粉体.用XRD,TEM,化学分析等手段对合成的TiN纳米粉体的物相组成、形貌、成分进行了分析.实验分析表明:在1000℃和1100℃下分别氮化5h,可以制备粒径大约为40nm和80nm的TiN粉体,其TiN的含量分别为95.40;和98.37;;而在1000℃条件下氮化时间减少到2h时,TiN的含量仅为58.36;.氮化温度和氮化时间是合成纳米TiN的重要因素,提高合成温度和延长氮化时间均可形成纯度较高的TiN纳米粉体,但延长氮化时间更有利于获得粒径小的氮化钛粉体.     

Mesomorphism Dependence on the Position of Substitution of a Pair of Esters

A novel homologous series of ethylene derivatives of thermotropic liquid crystals has been synthesized. The methoxy to octyloxy derivatives are nematogenic, the decyloxy to tetradecyloxy derivatives are smectogenic, in addition to nematogenic, and the hexadecyloxy homologue is smectogenic only. All the members of the series are enantiotropically mesogenic. Thermotropic behavior was determined by an optical polarizing microscope equipped with a heating stage and Differential Scanning Calorimetry (DSC) study. Analytical and spectral data confirm the molecular structures of homologues (infrared, nuclear magnetic resonance, mass spectra, X-ray, and DSC data). Textures of the nematic phase are threaded or Schlieren and that of smectic phase are focal conic fan-shaped of smectic A or C. Transition curves of the phase diagram behave in a normal manner except one or two deviations from the normal trend. The mesophase range (Sm+N) varies from 3°C to 44°C. The average thermal stability for smectic is 93°C and that for nematic 117.4°C. The LC behavior of the novel series is compared with a structurally similar known series.     

Effect of alumina on enthalpy of mixing of mixed alkali silicate glasses

The enthalpy of mixing of mixed alkali (Na₂O and K₂O) silicate glasses containing various concentrations of alumina was determined using an ion-exchange equilibrium method. For glasses with a constant alkali concentration, the enthalpy of mixing was found to become less negative with alumina addition. Consistent with our previous results on the enthalpy of mixing of alumina-free mixed alkali silicate glasses, the magnitude of enthalpy of mixing exhibited a good correlation with the molar volume mismatch of the corresponding two single alkali glasses as well as with the extent of conductivity mixed alkali effect, e.g. excess activation energy of conductivity, ΔE. The reduction of the magnitude of the enthalpy of mixing with alumina addition can be attributed to the reduction of non-bridging oxygen and ionic field strength. Combining the present results with results obtained earlier, the magnitude of the enthalpy of mixing for all mixed alkali (Na₂O and K₂O) silicate glasses with and without alumina was expressed by a simple function of a modified Tobolsky parameter, which takes into account the alkali concentration and the difference in cation-to-effective anion distances. The enthalpy of mixing data of the mixed alkali glasses was then compared with reported experimental data on the conductivity of mixed alkali aluminosilicate glasses. What appears to be conflicting experimental data can be understood in terms of the magnitude of the enthalpy of mixing and we can conclude that the mixed alkali effect is closely correlated with the negative enthalpy of mixing.     

电子显微分析在表征纳米晶体化学组分中的应用

纳米材料的化学组分及含量影响其光、电、声、热、磁等物理性能,电子显微分析是表征纳米晶体化学组分的重要方法之一.本文综述了X-射线能谱(EDS)、X-射线波谱(WDS)、电子能量损失谱(EELS)和选区电子衍射(SAED)等现代电子显微分析技术在表征纳米晶体化学组分、形貌、尺寸和结构等方面的应用及其研究进展,并比较了这些分析方法存在的差异,提出了其应用中存在的不足及今后的研发方向.     

Ni-ZrO2纳米复合电铸层的制备及纳米颗粒分布均匀性研究

研究了在复合电铸过程中,当其它工艺参数一定时,复合电铸层的沉积速率及其厚度随时间的变化趋势, 以及复合电铸层表面微观形貌随电沉积时间的变化趋势.测定了复合电铸层的组织成分,并就纳米颗粒在复合电铸层表面和横截面上分布的均匀性进行了评价.结果表明,复合电铸层表面平整,组织均匀致密,其组成主要是镍和所复合的纳米颗粒,纳米颗粒较为均匀地分散在复合电铸层中.     

Evolution of the Defect Structure of Zinc-Oxide as a Consequence of Tribophysical Activation

Zinc-oxide powder was tribophysically activated in a high-energy vibro mill in a continual regime in air for 3, 30 and 300 minutes with the purpose of modifying the powders physico-chemical properties. By analyzing of data obtained by X-ray powder diffraction, electron diffraction and transmission electron microscopy, the values of distances between corresponding crystallographic planes, average domain sizes of coherent scattering, i.e. crystallites, width of diffraction lines due to the existence of microstrains, and microstrain values, minimal dislocation densities, dislocation density due to microstrain and real dislocation density, and also average distances between dislocations were determined. The dependence of these values on the activation time was established, which enabled analysis of the evolution of the defect structure of zinc-oxide powders during tribophysical activation by grinding in the described regime.     

Some peculiarities of spectral proprieties of leukocytes

This article presents the results of spectral investigations of white blood human cells including absorption, fluorescence and phosphorescence (using low-temperature measurements). For this research, the main optical centres were identified and local distribution of emitting and absorbing centres into white blood human cells was determined. In addition, the spectra of normal and pathological (B-cell chronic lymphocytic leukemia, B-CLL) cells were compared.     

立方晶系晶体本征铁弹相变序参量的选取

在本征铁弹相变的软模理论的基础上,依据弹性本构关系和居里原理,给出了立方晶系晶体所有可能的自发应变的种类,研究了立方晶系晶体本征铁弹相变序参量的选取问题.以Th群和Oh群为例,阐明了不同类的序参量导致晶体对称性变化相同的的原因,提出了该情况下序参量选取的“就少不就多”的原则.得到了发生本征铁弹相变时所有可能的序参量及晶体的对称性的变化.     

Features of transformations in REE-containing systems of nitrate precursors in preparatory processes of formation of multifunctional oxide materials

Abstract

The complex study provides a reliable idea of ??the trends in the joint behavior of structural components in the water-salt systems of nitrate precursors of REE, alkaline, alkaline earth metals in the preparatory stages of the processes of forming multicomponent oxide polyfunctional materials on their basis with thermal activation. Stages of such transformations are revealed; The regularities of complex and phase formation in systems and factors influencing them are determined; A number of physicochemical properties of the intermediate phases formed - coordination lanthanides nitrates: their composition, types of compounds, atomic-crystalline structure, regularities of transformations during heat treatment were studied.