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1.
采用磁控反应溅射法,分别在室温和90℃条件下制备了两个系列的氧化银薄膜,其中氧氩比从1:4变化到2:1. SEM表明薄膜中的氧化银纳米颗粒尺寸均小于30nm.XRD表明随制备温度的提高AgO衍射峰减弱,Ag2O衍射峰增强,揭示了在成膜过程中,温度提高引起AgO热分解为Ag2O.分光光度计测量的反射谱和吸收谱表明氧化银的吸收边在400 nm附近,计算的氧化银禁带宽度约为3.1eV.通过对银的特征峰(312nm处)向短波方向的移动和消失分析证实氧氩比增大的确有助于银的完全氧化, 并且氧氩比2:1条件下制备的样品质量较佳. 相似文献
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采用化学液相沉淀工艺制备了过氧化银(AgO)粉体,研究了Na2S2O8用量、反应体系的pH值、反应时间等制备工艺参数对AgO产率的影响,并采用X射线衍射仪(XRD)及扫描电子显微镜(SEM)对制备的AgO粉体进行了表征.结果表明,优选的制备工艺是将AgNO3、Na2S2O8和SDBS的质量比定为1∶4.4∶1,然后在反应体系的温度达到60℃后通过滴加NaOH溶液调整反应体系的pH值为13.00,并维持反应时间30 min.随着AgNO3与SDBS的质量比从2.5升高到20.0,AgO粉末颗粒的形貌从近似的球形转变为球状和片状结构的混合物. 相似文献
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采用溶胶凝胶法在LiAlO2(302)衬底上制备了ZnO薄膜.用X射线衍射(XRD)和扫描电镜(SEM)对样品的结构和形貌进行了表征.XRD结果表明,随着热处理温度的升高(350℃、450℃、550℃、600℃、800℃),所得到的薄膜分别为单相ZnAl2O4(350℃),ZnAl2O4和ZnO的混合相(450℃)以及单相的ZnO(550℃、600℃、800℃),并且ZnO薄膜c轴择优取向的生长趋势随温度升高相应明显.SEM图像显示,随着热处理温度的升高,ZnO薄膜的粒径相应变大. 相似文献
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通过溶胶-凝胶法制备了单分散性的球形纳米Cu2O,采用无还原剂的取代反应法在上面负载一层纳米Ag,制备了核壳结构的Cu2O/Ag纳米复合材料.利用透射电镜(TEM)分析了纳米Cu2O/Ag的形貌、并用X射线衍射测(XRD)X射线光电子能谱(XPS)分析了其物相组成,利用紫外-可见光谱(UV-Vis)和光致发光光谱(PL)研究了其光谱特征,用大肠杆菌和金黄色葡萄球菌作为测试菌研究Cu2O/Ag抑菌性能.结果表明,Cu2O平均直径为150 nm,表面纳米Ag粒子直径为7 nm,形成核壳结构Cu2O/Ag对大肠杆菌抑菌率为93 ;, 对金黄色葡萄球菌为95;. 相似文献
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采用烧结法,选用Na2O-B2O3-SiO2为基础玻璃(NBS),按照氟磷灰石组成配比添加CaO,P2O5,CaF2三种组分,制备Na2O-B2O3-SiO2-CaO-P2O5-CaF2生物微晶玻璃.利用差热分析、X射线衍射分析及扫描电镜等测试手段对微晶玻璃物相、微观结构进行了测试和分析,并采用模拟体液对样品的生物活性进行了验证.结果表明:随着热处理温度升高,样品的晶化程度逐步提高,当热处理温度在750℃时,可以获得主晶相为氟磷灰石,晶粒尺寸在100 nm左右、其晶化率≥80;的微晶玻璃样品,通过模拟体液浸泡实验证明了样品具有一定的生物活性. 相似文献
7.
溶胶-凝胶法制备MgxZn1-xO及其特性 总被引:2,自引:1,他引:1
采用溶胶-凝胶法制备了不同组分(x=0.1~0.3)的MgxZn1-xO前驱体,并对它进行不同温度的热处理(550℃~1000℃).X射线衍射(XRD)结果表明,Mg0.1Zn0.9O具有和ZnO一样的衍射谱,为六方纤锌矿结构,而且随着热处理温度的升高,ZnO衍射峰的强度逐渐增强,半高宽不断减小;Mg元素掺杂浓度增大后,出现了MgO的峰位.扫描电子显微镜(SEM)显示Mg0.1Zn0.9O晶粒粒径分布较均匀;热处理温度升高,晶粒的尺寸不断变大.用室温荧光光谱(PL)分析了经过550~1000℃热处理获得的Mg0.1Zn0.9O粉末,结果发现除了550℃下处理的样品,其它都有紫外发射峰(350nm左右),而且随着热处理温度的升高紫外峰有明显的蓝移现象. 相似文献
8.
通过控制水含量,用水热法制备了CaTi2O4(OH)2片状结构。通过对水含量为50 mol条件下所制备的CaTi2O4(OH)2片状结构煅烧来制备CaTiO3片状结构。当热处理温度≤400℃,CaTi2O4(OH)2纳米片状结构稳定存在。当热处理温度为650℃和750℃,制备了CaTiO3片状结构。采用XRD、SEM和TEM等测试方法对片状结构进行表征,并对CaTi2O4(OH)2片状结构向CaTiO3片状结构转化的反应过程和形成机理进行分析。在热处理温度400℃时,样品的首次放电比容量最大,可达到168.5 mAh/g。当热处理温度继续升高到650℃和750℃,样品的首次充放电容量分别为18.9 mAh/g和5 mAh/g。这说明发育完善的CaTi2O4(OH)2片状结构有利于电化学过程中离子的嵌入和脱出。 相似文献
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采用微波辐射法制备了沉积于碳纳米管(CNTs)表面的氧化铋(Bi2O3)纳米粒子(Bi2O3/CNTs),用扫描电子显微镜(SEM)、光电子能谱(XPS)和X射线衍射(XRD)对制备的Bi2O3/CNTs纳米粒子进行了表征。研究了Bi2O3/CNTs纳米粒子对二硝酰胺铵(ADN)的催化热分解。结果表明,纳米Bi2O3均匀沉积在CNTs表面,平均粒径为8nm;添加3%Bi2O3/CNTs纳米粒子的ADN的初始热分解温度降低了12.8℃,热分解终止温度降低了29.3℃;NH4N(NO2)2→NH4NO3 N2O为ADN初始热分解的主导反应。 相似文献
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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
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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
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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
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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
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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
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O. Dryuchko D. Storozhenko A. Vigdorchik N. Bunyakina I. Ivanytska K. Kytaihora 《Molecular Crystals and Liquid Crystals》2018,672(1):199-214
AbstractThe 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. 相似文献
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K. Sethuraman R. Ramesh Babu N. Vijayan R. Gopalakrishnan P. Ramasamy 《Crystal Research and Technology》2006,41(8):807-811
A new organic single crystal of semicarbazone of cyclohexanone (SCCH) has been synthesized and grown as a bulk single crystal by low temperature solution growth technique for the first time in the literature. The grown crystal has been confirmed by X‐ray diffraction and proton nuclear magnetic resonance spectral analyses and also characterized by FT‐ir and FT‐Raman studies. Thermal properties of the grown crystals were studied by thermogravimetric and differential thermal analyses. Optical transmittance was studied by ultraviolet‐visible spectrum and the second harmonic generation property was tested by using Q switched Nd: YAG laser as a source. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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M. Thamilselvan K. Premnazeer D. Mangalaraj Sa. K. Narayandass Junsin Yi 《Crystal Research and Technology》2004,39(2):137-142
A systematic investigation on the effect of substrate temperature on the structure, optical absorption and density of states of vacuum evaporated gallium monoselenide (GaSe) thin films is reported. The X‐ray diffraction analysis shows an occurrence of amorphous to polycrystalline transformation in the films deposited at higher‐temperature substrates (573K). The compositional analysis is made with Auger Electron Spectroscopy (AES). The thickness of the film (175nm) is measured by a multiple beam interferometery. Optical characteristics of the GaSe sample have been analyzed using spectrophotometer in the photon energy range of 1.0 ‐ 4 eV. The absorption mechanism has been recognized and the allowed indirect as well as forbidden direct transitions have been found. As‐deposited films show two indirect and allowed transitions due to spin‐orbit splitting of the valence band, as reported here for the first time. Low field conduction have enabled us to determine the density of states in amorphous and poly‐GaSe films. The amorphous and polycrystalline GaSe thin films have localized states density values of N (EF) = 1.686 × 1017 cm‐3 eV‐1 and 1.257 × 1015 cm‐3 eV‐1 respectively. The experimental results are interpreted in terms of variations in the density of localized states due to progressive decrease of the unsaturated bonds during deposition. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献