共查询到20条相似文献,搜索用时 62 毫秒
1.
2.
采用改进垂直布里奇曼法生长出的磷锗锌(ZnGeP2,ZGP)晶体中存在各种缺陷,导致其红外透过率较低,刚生长的晶体不能直接用于制备红外非线性光学器件.分别采用真空、同成分粉末包裹和真空-同成分粉末包裹的复合退火工艺对生长的ZGP晶体进行了退火热处理研究.应用傅立叶红外光谱仪(FTIR)、高阻仪(HRM)、X射线能谱仪(EDS)等对退火前后的晶体性能和成分进行了测试分析.结果表明,三种方法退火后晶体的红外透过率和电阻率都得到改善,其中复合退火工艺的改善效果最为显著,晶体红外透过率由41;提高到60;,电阻率由2.5×108 Ω·cm提高到7.2 ×108 Ω·cm,晶体成分接近ZGP理想化学配比,退火后晶体的光学和电学性能得到显著改善,可用于ZGP-OPO器件制作. 相似文献
3.
4.
以高纯(6N) Cd、Si、P单质为原料,采用双温区气相输运法和改进的垂直布里奇曼法合成生长出等径尺寸为φ17 mm×65 mm的CdSiP2单晶锭,经切割抛光得到CdSiP2晶片.将样品分别置于真空、镉气氛、磷气氛和在同成分粉末包裹中进行了退火试验.采用X射线能量色散谱仪(EDS)和傅里叶红外分光光度计(FTIR)对退火前后的晶片组分及红外透过谱进行了测试分析.结果表明:四种氛围退火前后样品的组分变化不大,原子比接近理想的化学计量比;镉气氛下退火对晶片的红外透过率改善较为显著,在1600 ~ 4500 cm-1范围内的红外透过率由46;~52;提高到51; ~57;,接近CdSiP2晶体红外透过率的理论值. 相似文献
5.
6.
稀释磁性半导体Cd0.9Mn0.1Te晶体的退火改性 总被引:2,自引:2,他引:0
运用缺陷化学原理近似计算了Cd0.9Mn0.1Te晶体的点缺陷浓度,得到了晶体成分与理想化学计量比偏离最小时的退火条件.利用该退火条件,指导了Cd0.9Mn0.1Te晶体的两温区退火实验,并分析了退火对晶片性能的影响.结果表明:在973 K,Cd气氛下对Cd0.9Mn0.1Te晶片退火140 h后,晶片(111)面的X射线回摆曲线的FWHM值由退火前的168.8' 降至108',红外透过率由退火前48;提升到64;,接近晶体的理论透过率,电阻率也由退火前的2.643×105 Ω·cm提高到4.49×106 Ω·cm.由此可见,对生长态的Cd0.9Mn0.1Te晶体进行退火实验能提高晶体的结晶质量,补偿晶体的Cd空位点缺陷,使晶体成分接近理想的化学计量比. 相似文献
7.
采用AIM-8800红外显微镜观察了CdGeAs2晶体的面扫描红外透过图像,分别在2.3~4μm、4~8 μm和8~18μm三个波段对退火前后的CdGeAs2晶片红外透过率和面扫描红外透过图像进行了对比分析,研究了晶体的红外均匀性.结果表明,CdGeAs2晶体在多晶粉末包裹下经450℃退火150 h后,其红外透过率和红外透过均匀性都得到较大程度的改善,其中在2.3 ~4μm和4~8μm波段的改善效果尤为显著;分析了影响晶体红外透过率和均匀性的主要因素,探讨了改善晶体均匀性的可能途径.研究结果对于快速评判CdGeAs2晶片质量具有重要的实用价值. 相似文献
8.
采用改进布里奇曼法生长出外观完整的AgGa1-xInxSe2(x=0.2)单晶锭,晶体的红外透过率低,不能直接用于红外非线性光学器件制备.采用TA公司生产的SDTQ-600热分析仪进行DSC-TGA测试,发现其熔点为826.69℃,结晶点为750.86℃,总失重约为3.9217;.采用同成份粉末源包裹晶体,在抽空封结后进行退火处理.退火处理后晶体的红外透过率有明显改善.在4000cm-1~7000cm-1范围内红外透过率由原先低于25;改进到高于40;;在750cm-1~4000cm-1范围的红外透过率由原先低于45;改善到超过50;,在2000cm-1 ~750cm-1区域甚至高达60;.结果表明:采用同成分粉末源包裹,在抽空封结后退火处理能有效提高AgGa1-xInxSe2晶体的红外透过率,改善晶体的光学均匀性,退火后的晶体适合红外非线性光学器件制备. 相似文献
9.
10.
本文采用中频感应提拉法成功生长了LaAlO3和Ce3+:LaAlO3晶体.沿生长方向即α轴方向切割、抛光后得到实验样品.测试了氢气退火前后纯LaAlO3和Ce3+:LaAlO3从190nm到2500nm的吸收谱和透过谱.测试结果表明:纯LaAlO3晶体在196~220nm处出现宽带吸收,氢气退火后此一波段的吸收系数明显降低;未退火的Ce:LaAlO3晶体在196~209nm,246nm,314nm出现明显的吸收波段,氢气退火后其吸收谱发生显著变化,在198,206,214,246和314nm处出现对应于Ce3+的4f-5d的跃迁吸收;Ce:LaAlO3晶体较之纯LaAlO3晶体在红外区的透过率要高;氢气退火后,Ce:LaAlO3晶体和纯LaAlO3晶体在红外区的透过率下降. 相似文献
11.
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. 相似文献
12.
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. 相似文献
13.
原位氮化法制备TiN纳米粉体 总被引:3,自引:0,他引:3
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. 相似文献
14.
On the influence of structural features of DNA on the possibility of metabolic transfer of electrons
A. D. Suprun 《Molecular Crystals and Liquid Crystals》2020,701(1):28-39
AbstractA 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. 相似文献
15.
P.J. Lezzi 《Journal of Non》2011,357(10):2086-2092
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. 相似文献
16.
17.
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. 相似文献
18.
N. G. Kakazey L. A. Klockov I. I. Timofeeva T. V. Sreckovic B. A. Marinkovic M. M. Ristic 《Crystal Research and Technology》1999,34(7):859-866
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. 相似文献
19.
Yu. G. Terent'yeva V. M. Yashchuk O. M. Snitserova M. Yu. Losytsky 《Molecular Crystals and Liquid Crystals》2017,642(1):81-88
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. 相似文献