Au/Al2O3催化剂的UV-Vis谱研究

研究了十六烷基三甲基溴化铵 (CTAB) /正己醇 /水体系的W/O微乳体系中 ,几种主要实验参数对用NaBH4还原氯金酸溶液制得的金纳米粒子大小的影响。实验结果表明 :微乳体系中水与表面活性剂的摩尔比rw 在所研究的范围内对金粒子大小影响不大 ,而氯金酸溶液的浓度对金粒子大小影响较大。通过优化制备条件 ,用两种不同的方法制备了Au/Al2 O3 催化剂 ,并用紫外 可见光谱、透射电镜 (TEM)和X射线衍射(XRD)对其进行表征 ,初步考察了不同制备方法对催化剂中活性组分Au粒大小的影响     

IR Spectra of Be(IO3)2.nH2O (n = 4, O) and of the Deuterated Analogue

Abstract

The compounds of beryllium - Be(IO₃)₂.4H₂O, its deuterated analogue and Be(IO₃)₂ were studied by IR-spectroscopy over the range of 200 to 4000 cm^?1.     

FT-IR Study of the Adsorption of Propane and Propene on V2O5/γ-Al2O3 Catalyst

It has been observed on the oxidized V₂ O₅/γ-Al₂ O₃ that C₃H₆ form alkoxides which were converted to acetone during the desorption of adsorbate phase at 373 K. C₃ H₈ may form π-complexes on the reduced form of the same catalyst. However, the intensities of the bands in the adadsorption of C₃ H₈ were very weak as compared with the case of C₃ H₆ adsorption. Therefore, it was not reasonable to assign these bands clearly as any of the surface type species.     

V centers in single crystal Al2O3

From optical and thermal bleaching experiments it is concluded that the 400 nm absorption band which appears in Al₂O₃ after γ-irradiation is a composite V band. One of its components is attributed to the V^-_OH center which also is responsible for a localized vibrational band at 3316 cm^-11 analogous to the one observed for the V_OH center in MgO. The irradiation also results in electron trapping at Cr³⁺ impurity ions to produce a band at 227 nm. Annealing at 170°C destroys the V^-_OH center by releasing holes which convert the Cr²⁺ to Cr³⁺ with an attendant thermoluminescence.     

Yb:Y3Al5O12/Y3Al5O12复合晶体的制作和光谱性能

采用热键合技术,制作中运用不同的工艺参量制作出12片Yb:Y3Al5O12/Y3Al5O12(Yb:YAG/YAG)复合.晶体.利用偏光显微镜对其键合界面进行了观察,研究了样品的透射光谱,从而确定出复合晶体合适的制作工艺.通过透射光谱的形状和透射率来表征复合晶体键合界面的质量.研究表明Yb:YAG/YAG复合晶体键合质量较好,可实现一体化.     

Electrical transport mechanism in Al/V2O5/Al microdevices

The current-voltage characteristics of metal-insulator-metal microdevices fabricated with electron-beam evaporated vanadium pentoxide films have been studied in order to understand the electrical transport mechanism in these films. The dependence of transport properties on various factors such as film thickness, substrate temperature, and applied field, has been established. The results revealed that the electrical transport follows a Schottky-type mechanism at lower electrical fields and a Poole-Frenkel-type at higher electrical fields than 2×10⁶ V/m.     

Accumulation and flow of charge in MOS structures with Al2O3 and SiO2-Al2O3 films on silicon

A expérimental study has been carried out on the processes involved in the accumulation and flow of charge in MOS structures with thin films of Al₂O₃ and SiO₂-Al₂O₃ under various polarization conditions. The activation energy, the frequency factors, the sites of the trapping centers of the polarization charge, and the character of the flow of charge on thermal depolarization have been studied. It is shown that in a structure with a double-layer dielectric, the instability of the charge cannot be explained by the Maxwell-Wagner polarization model in its pure form because of the accumulation of charge in the spatially distributed trapping centers throughout the Al₂O₃ film. The parameters of the traps at the interface between the dielectrics have been determined and the contribution made to the instability of the charge by the migration of ions in these particular structures has been evaluated.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 7–14, April, 1978.     

Hyperfine interaction of 25Al in α-Al2O3 and its quadrupole moment

A brief review is presented of recent work with the Precision Penning Trap Mass Spectrometer, formerly at MIT, now at Florida State University. This includes atomic mass comparisons using single trapped ions; mass comparisons using two simultaneously trapped ions alternated between large and small cyclotron radii; and measurement of the dipole moment of a molecular ion using the polarizability-induced shift in cyclotron frequency.     

固体和熔融碱金属碳酸盐的Raman光谱研究

用高温共焦显微激光 Raman光谱仪测定了不同温度下固体和熔融态的碳酸钠、碳酸锂以及不同成份的固态和液态 Li2 CO3- Na2 CO3混合物的 Raman光谱图 ,分析了 Na+和 Li+对碳酸根离子作用力的变化。根据 CO32 -对称伸缩振动模的波数移动情况 ,在固态混合物中也发现了混合效应     

Na_2Si_2O_5·xFe_2O_3玻璃和熔体的Raman光谱研究

通过溶胶 凝胶法制取了Na2Si2O5·xFe2O3(x=1,3,5%)玻璃,其玻璃和熔体的Raman谱图表明随铁含量的增加920cm-1谱峰明显增强,而1000cm-1附近则出现一个小的尖峰。讨论了引起这些谱峰变化的原因。     

Effect of neutron irradiation on optical spectra of α-Al2O3 and α-SiO2 single crystals

Using two crystal dielectrics (α-Al₂O₃ and α-SiO₂) as examples, the author studied the effect of large neutron-radiation doses on their optical spectra. The variation in IR spectra in the region of α-SiO₂ stretching and deformation vibrations is investigated; its relation to changes in the structure of the irradiated crystal is discussed. Institute of Nuclear Physics, Academy of Sciences of the Republic of Uzbekistan, Ulugbek Settlement, Tashkent, 702132. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 1, pp. 135–138, January–February, 1999.     

IR spectra of glazes with a lower B2O3 concentration

Belarusian State Technological University, 13a, Sverdlov Str., Minsk, 220630, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 63, No. 5, pp. 870–872, September–October, 1996.     

Preparation of sol-gel method P2O5-Al2O3-SiO2 glasses and their characterization

Nanostructures P₂O₅-Al₂O₃-SiO₂ glasses were prepared by sol-gel method. The glasses were characterized by XRD, FTIR and TG/DTA methods. The average pore size of the glass was less than 3 nm as measured by N₂ adsorption — desorption method. The thermal stability was measured as a function of decomposition temperature and weight loss calculations. Proton conductivities of all samples increased with an increase in relative humidity (40–90 %), indicating that continuous paths suitable for proton conduction were developed when glasses heat treated at 300 °C due to the adsorption of water. The temperature dependence of the conductivity for all compositions increases with increasing temperature in the range 30–90 °C with relative humidity 70 %. The overall conductivity was in the range 10⁻⁴–10⁻³ S/cm for compositions.     

Radiation stability of powders in mixtures with Al2O3 nanoparticles

A comparative research was conducted to investigate the absorption spectra of barium titanate powders mixtures with aluminum oxide micro- or nanopowders irradiated by electrons. It was established that the addition of aluminum oxide nanopowder enhances the radiation stability of mixtures, which increases with the concentration of nanoparticles. Stability augmentation of mixtures under irradiation is caused by the decrease in the concentration of radiation defects in the anion sublattice of barium titanate.     

Dielectric loaded surface plasmon polariton properties of the Al_2O_3–Al nanostructure

Surface plasmons(SPs) in ultraviolet(UV) have attracted a great deal of attention because of their emerging applications in energy resources, environmental protection, and biotechnology. In this article, the dielectric loaded surface plasmon polariton(DLSPP) properties of the Al_2O_3–Al nanostructure are investigated theoretically. Sharp SP responses can be obtained in deep UV by setting an insulator grating on the aluminum film. It is found that the height of the grating element,the lattice parameter, and the filling factor can all modulate the DLSPPs of the Al_2O_3–Al nanostructure. We further find that this structure is sensitive to the embedding medium and can serve as a refractive index sensor in the UV region. The corresponding sensitivity increases with the decrease of the filling factor. The Al_2O_3–Al nanostructure may be useful for medical diagnostics and biotechnology in deep UV.     

碳酸钙在溶液中的演化机理

以EDTA作为添加剂,在CaCl₂/NaCO₃混合液中采用共沉淀法制备了碳酸钙,并探讨它在母液中的演化机理. 热力学和动力学计 算表明虽然形成无定形碳酸钙(ACC)的驱动力小于方解石和球霰石,但在共沉淀反应的初始阶段ACC的形核速率高于方解石和球霰石. 随着陈化时间的延长,最新生成的碳酸钙成为球霰石和方解石异相形核的活性点. 通过SEM发现ACC和球霰石在母液中通过溶解-再结晶机理转化成方解石. 此外,EDTA添加剂不仅提高了ACC和球霰石的稳定性,而且有助于碳酸钙在母液中陈化7天后转化成长棒状、菱形的方解石晶体. 如果将碳酸钙放置在空气介质中,ACC和球霰石也可以通过溶解-再结晶反应转化成方解石,但其转化速率低于溶液介质.     

臭氧在SnO2表面吸附的红外光谱研究

以SnO2催化臭氧化降解高浓度糖蜜酒精废水为探针反应,研究SnO2催化臭氧化降解糖蜜酒精废水的活性,并采用红外光谱研究臭氧在SnO2及金属氧化物改性的SnO2催化剂表面的吸附行为。结果表明:由纯氧源制得的O3在SnO2表面吸附的红外光谱上的1 027和1 055 cm-1及2 099和2 122 cm-1处存在两处明显的吸收双峰,而空气制备的O3在SnO2表面与CO及CO2等存在竞争吸附,使得O3的吸附减少,催化臭氧化降解糖蜜废水的降解率下降。催化剂助剂对SnO2催化臭氧化降解糖蜜酒精废水有较大的影响。采用Fe2O3,NiO,CuO,ZnO,MgO,SrO及BaO等金属氧化物为助剂改性的SnO2在2 236和2 213 cm-1,1628和1 599 cm-1出现强度相似的吸收峰,但是几种催化剂对CO2和CO的吸附差别较大,过渡金属改性的SnO2在1 580~1 070 cm-1处出现较宽的吸收峰,碱土金属氧化物改性的SnO2催化剂在1 580~1 070 cm-1之间,出现了1 298和1 274 cm-1两个新的峰,从而引起了不同助剂催化臭氧化的活性差别,碱土金属改性的SnO2对糖蜜酒精废水的催化臭氧化脱色效果明显优于过渡金属改性的SnO2,其中BaO改性的SnO2催化剂的活性最好。     

稀土掺杂P2O5-Al2O3-BaO玻璃的制备及其结构研究

稀土掺杂磷酸盐玻璃具有优异的光学和光谱特性,在激光介质、有色滤光材料等领域中有着重要的应用。在P2O5_Al2O3_BaO_Sm2O3(PABS)玻璃形成能力研究的基础上,借助MAS NMR、红外光谱等分析手段,研究了玻璃的结构、玻璃组成与热处理等对玻璃结构的影响。结果表明:不同组成PAB(S)玻璃的31P MAS NMR谱在-20ppm~-25ppm范围内均存在单一的特征信号峰,对应于磷氧多面体[PO4]的Q2型结构;在18ppm、-12ppm和-36ppm处27Al的MAS NMR谱的三个特征信号峰分别对应于27Al的[AlO5][、AlO6]、[AlO6]配位结构,稀土离子的掺入以及热处理均使得[AlO6]向[AlO5]转变;玻璃的网络结构主要由Q2型[PO4]、[AlO5]和[AlO6]构成,并P_O_P、P_O_Al的形式相连接。玻璃在1383 cm-1处出现的吸收峰可能是玻璃结构中形成了P_O_Sm键所致。