衬底对宽带隙CGS薄膜的影响

分别在Al∶ ZnO(ZAO)薄膜和Mo薄膜两种不同衬底材料上,采用“三步法”共蒸发工艺沉积了约0.8 μm厚的CuGaSe2(CGS)薄膜,用X射线衍射仪测量薄膜的织构,研究不同衬底材料对CGS薄膜的影响.在ZAO薄膜底电极上沉积的CGS薄膜的(112)衍射峰强度较Mo薄膜底电极上减弱,(220/204)衍射峰反而增强.     

热处理对Al掺杂ZnO薄膜晶体结构及光电性能的影响

采用溶胶凝-胶法在普通玻璃衬底上制备了具有c轴择优取向的Al掺杂ZnO透明导电薄膜.实验中将热处理过程分解为预烧、空气退火和真空退火三个部分,研究了各个步骤对于ZAO薄膜晶体结构和光电性能的影响.结果表明, 500 ℃预烧550 ℃空气退火的薄膜,经过550 ℃,1×10-2 Pa真空退火后,其晶体结构和光电性能达到最佳,电阻率最低达到1.77×10-3 Ω· cm,可见光范围内的平均透过率约为85;.     

离子液体辅助溶胶-凝胶法制备ZnO:Al透明导电薄膜及其光电性能研究

采用溶胶-凝胶法,以离子液体为辅助溶剂,在玻璃衬底上制备了ZnO:Al(ZAO)薄膜.通过X-射线衍射(XRD)、场发射扫描电镜(FE-SEM)、紫外-可见分光光度计(UV-Vis)和霍尔效应等测试手段,分析了不同Al掺杂浓度ZAO薄膜的微观结构、光学和电学性能.结果表明,所制备的薄膜为非(002)取向的多晶膜.随着Al离子掺杂浓度的提高,薄膜的(002)晶面取向增强,晶粒逐渐由片状向球形转变,电阻率先降低后升高.进一步研究发现,在还原气氛NH3下退火可显著降低薄膜的电阻率,Al掺杂浓度为1 mol;时,薄膜电阻率达到4.7×10-2Ω·cm,可见光透过率平均在80;以上.     

生长和退火温度对磁控溅射法制备的ZnO薄膜性能的影响

利用磁控溅射法于500 ℃、550 ℃、600 ℃和650 ℃下在Al2O3(001)衬底上生长ZnO薄.对生长的ZnO薄膜后分别进行了800 ℃退火和1000 ℃退火处理.利用X射线衍射(XRD)、霍尔测试仪和透射谱仪对薄膜的结构、电学和光学性质进行了研究,结果表明合适的生长温度和退火温度能够提高ZnO薄膜的结晶质量和性能.     

离子液体辅助溶胶-凝胶法制备ZnO∶Al透明导电薄膜及其光电性能研究

采用溶胶-凝胶法,以离子液体为辅助溶剂,在玻璃衬底上制备了ZnO∶Al(ZAO)薄膜。通过X-射线衍射(XRD)、场发射扫描电镜(FE-SEM)、紫外-可见分光光度计(UV-Vis)和霍尔效应等测试手段,分析了不同Al掺杂浓度ZAO薄膜的微观结构、光学和电学性能。结果表明,所制备的薄膜为非(002)取向的多晶膜。随着Al离子掺杂浓度的提高,薄膜的(002)晶面取向增强,晶粒逐渐由片状向球形转变,电阻率先降低后升高。进一步研究发现,在还原气氛NH3下退火可显著降低薄膜的电阻率,Al掺杂浓度为1 mol%时,薄膜电阻率达到4.7×10-2Ω·cm,可见光透过率平均在80%以上。     

退火温度对Li:ZnO薄膜紫外发射性能影响

利用溶胶-凝胶法在Si衬底上制备不同退火温度的Li∶ZnO薄膜。借助X射线衍射(XRD)、X射线光电子谱(XPS)、扫描电镜(SEM)和光致发光(PL)谱研究样品结晶质量、成分、表面形貌和发光特性。结果表明:所有样品均高度c轴择优取向生长;随退火温度升高,样品结晶性变好,紫外发射增强。LiOH在退火温度超过700℃分解,使Li、H进入到ZnO晶格,在ZnO薄膜中形成LiZn-H复合缺陷,这种复合缺陷使H被困在ZnO薄膜中,形成H施主,显著提高ZnO薄膜紫外发光强度,抑制ZnO薄膜绿光发射。     

热处理工艺对室温制备ZnO:Al薄膜结构与光电性能的影响

采用室温溅射加后续退火工艺制备了ZnO∶ Al透明导电薄膜.研究了热处理工艺对薄膜微观结构和光电性能的影响.研究表明:退火有助于减小Al~(3+)对Zn~(2+)的取代造成的晶格畸变,消除应力,促进晶粒长大,有效提高电子浓度和迁移率,降低电阻率;当溅射功率为80 W、退火温度为320 ℃时,薄膜的电阻率可低至8.6×10~(-4) Ω·cm;退火气氛对薄膜的导电性能有较大影响,真空退火可使吸附氧脱附,大大降低薄膜的方块电阻.而退火温度和退火气氛均对ZnO∶ Al薄膜的透光率没有明显影响,薄膜的透光率在86;以上.     

退火处理对ZnO薄膜发光特性的影响

用脉冲激光沉积法(PLD)在MgO(100)、α-Al2O3(0001)和MgAl2O4(111)衬底上沉积了ZnO薄膜,测量了它们的发射光谱,观察到430nm的蓝光发射,并研究了退火、衬底和激发波长对ZnO薄膜这一蓝光发射的影响.指出ZnO薄膜中430nm的蓝光发射是由锌填隙原子缺陷能级到价带顶能级间的跃迁以及电子从氧空位浅施主能级到价带顶能级间的跃迁两种机理共同作用的结果.在MgO衬底上沉积的ZnO薄膜在350nm光激发下蓝光发射峰最强.     

退火气氛和镧掺杂浓度对ZnO薄膜结构和光学性能的影响

采用溶胶-凝胶浸渍提拉法在玻璃衬底上制备Zn1-xLaxO(x=0～0.04)(LZO)薄膜,分别在空气、氮气和氩气条件下进行退火,探讨了不同退火气氛和不同镧掺杂浓度对其结构和光学性能的影响.XRD和SEM结果表明:氩气退火条件下ZnO的晶粒尺寸比空气退火条件下和氮气退火条件下的晶粒尺寸略小,且ZnO晶粒的尺寸随着镧掺杂浓度的增加而减小.薄膜光致发光(PL)测量表明:紫光发光带中心在氩气下退火相对于空气下退火存在略微的蓝移,而在氮气下退火则相反;ZnO紫光发光带的位置随着镧掺杂浓度的增加先红移而后蓝移.禁带宽度在镧掺杂量为2;时达到最小值,说明镧可以有效地调节ZnO的禁带宽度.     

Si(111)衬底上ZnO薄膜的磁控溅射法制备及表征

采用磁控溅射法在(111)单晶硅衬底上沉积了ZnO薄膜,并研究了退火温度对ZnO薄膜晶体质量、晶粒度大小、应力和光致发光谱的影响.X射线衍射(XRD)表明薄膜为高度c轴择优取向.不同退火温度下的ZnO薄膜应力有明显变化,应力分布最为均匀的退火温度为500℃.室温下对ZnO薄膜进行了光谱分析,可观测到明显的紫光发射(波长为380nm左右).实验结果表明,用磁控溅射法在单晶硅衬底上能获得高质量的ZnO薄膜.     

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.     

On the influence of structural features of DNA on the possibility of metabolic transfer of electrons

Abstract

A fragment of a DNA molecule is considered as one of the channels of metabolic electron transfer. The heterogeneity of the complementary chains is effectively taken into account. This made it possible to find the speed of the electron injected into the DNA conduction band and the current density that it creates. Estimates of electron mobility in nucleic acid chains are made. They were an order of magnitude smaller than that of typical semiconductors. For the specific conductivity of nucleic acid chains, estimates provide a conductivity of one to two orders of magnitude lower than in graphite.     

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.