SEM and TEM analysis of composite of ZrO2-Ti system

3Y-ZrO₂-Ti composites obtained by slip casting method were studied by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Moreover, the Vickers hardness was measured. The experiments show the complex microstructure of composites. The tetragonal zirconium dioxide (t-ZrO₂) and monoclinic zirconium dioxide (m-ZrO₂) as a composite matrix were detected at XRD analysis. SEM observations revealed that Ti -rich phase are uniform distributed in composites. Moreover, the large and very fine precipitations were found. The very fine Ti rich precipitations were located at ZrO₂ grain boundaries as well as in the triple-points. TEM experiments confirmed that in the sintered composites 3Y-ZrO₂ – 10%Ti the uniaxial ZrO₂ grains (100–600 nm), fine monoclinic martensitic plates and fine round monoclinic particles (20–40 nm) of ZrTiO₂ phase were exist. The complex microstructures of 3Y-ZrO₂-Ti composites have a high hardness as a result of existing fine ZrTiO₂ and other Ti oxides precipitations.     

Electron-stimulated desorption of D (H) from condensed D2O (H2O) films

The electron-stimulated desorption (ESD) of D⁻ and H⁻ ions from condensed D₂O and H₂O films is investigated. Three low-energy peaks are observed in the ESD anion yield, which are identified as arising from excitation of ²B₁, ²A₁ and ²B₂ dissociative electron attachment (DEA) resonances. Additional structure is observed between 18 and 32 eV, which may be due to ion pair formation or to DEA resonances involving the 2a₁ orbital. The ion yield resulting from excitation of the ²B₁ resonance increases as the film is heated. We attribute the increase in the ion yield to thermally induced hydrogen bond breaking near the surface, which enhances the lifetimes of the excited states that lead to desorption.     

Enhanced superconductivity in zirconium after H(D) implantation

Zirconium foils (superconducting transition atT _c =0.7 K) were implanted at liquid helium temperatures with hydrogen, deuterium and helium. In all cases a remarkable increase ofT _c was observed. Implantation of the inert He atoms leads only to the introduction of lattice defects, which is known to increaseT _c of Zr. However, the implanted H and D atoms exert an additional influence on the superconducting behavior based on a change of the electronic properties and an increase of the electron-phonon coupling. Introduction of lattice defects seems to account for theT _c increase to 1.49 K after He implantation, whereasT _c is even more enhanced by implantation of the hydrogen isotopes. The maximum values forT _c are 3.14 K for H and 4.65 K for D implantation. The concentration necessary to produce a saturation inT _c for both isotopes is H(D)/Zr0.13. The remarkably highT _c for the heavier isotope corresponds to an extreme inverse isotope effect. A smaller inverse isotope effect was found earlier in the Pd –H(D) system, where it could be explained by anharmonic effects.Dedicated to Prof. Dr. W. Buckel on the occasion of his 60th birthday     

Specific heat of TbMn2(H,D)2

Specific heat (SH) measurements on TbMn₂(H,D)₂ powders have been performed in the temperature range from 2 to 350 K, in zero magnetic field and in 9 T. Due to the low heat conductivity of the samples, the measurements were carried out on a mixed Cu- and sample-powder pellet. For TbMn₂, the anti-ferromagnetic phase transition was manifest by a single SH peak at T_N=47 K, whereas a double SH peak at 281 and 288 K and an upturn below 5 K were observed for the hydride sample. Upon applying the magnetic field of 9 T, the SH upturn was suppressed, whereas no visible influence was found on the specific heat in the whole temperature range above 10 K as well as on the double peak.     

Electronic behavior of visible light sensitive ZrO2/Cr2O3/carbon clusters composite materials

Nano-sized ZrO₂/Cr₂O₃/carbon clusters composite materials were successfully obtained by the microwave-irradiated calcinations of a Zr(acac)₄/Cr(acac)₃/epoxy resin complex. The compositions of the resulting composite materials were determined using ICP, elemental analysis and surface characterization by XRD, SEM and TEM. The UV–Vis spectra of the composites were also obtained. ESR spectral examinations of the composites indicate that an electron transfer takes place in the process Cr₂O₃ → carbon clusters → ZrO₂. The composite materials have been found to show visible light-responsive catalytic activities.     

Vibrational analysis of NaM2OH(H2O)(MoO4)2/D2O [M=Ni,Zn]

The infrared and Raman spectra of NaNi₂OH(H₂O)(MoO₄)₂ and NaZn₂OH (H₂O)(MoO₄)₂ and their partially deuterated analogues are recorded and analysed on the basis of vibrations of MoO ₄ ²⁻ tetrahedra and H₂O molecules. The MoO ₄ ²⁻ groups are found to be more distorted in NaNi₂OH(H₂O)(MoO₄)₂ than in the other compound. Bands indicating the presence of H₃O⁺ ions are not observed in NaZn₂OH(H₂O)(MoO₄)₂ ruling out the possibility of the formulation of NaZn₂OHO(MoO₃OH)₂. Hydrogen bonds of medium strength are present in both the compounds.     

A Vibrational Normal Coordinate Analysis of H(D)NCO and H(D)NCS

The infrared spectra of HNCO and HNCS are quite complicated and the band assignments are still disputed. In this note we try to add some arguments based on the normal coordinate analysis in favour of the recently proposed assignments^1,2. The analysis was performed by the standard GF method with the frequency assignment due to Ashby and Werner¹ for HNCO, and Durig and Wertz for HNCS². The frequencies only were used in the iteration procedure and the results are given in the Table.     

势垒高度对Cl+H2(D2)反应的影响

使用三维含时波包方法在两个势能面上研究了Cl+H2(D2)反应．所使用的两个势能面都是从CW(Capecchi和Wener)势能面得到的，第一个是CW势能面的基态面加自旋轨道耦合修正，第二个是CW势能面的基态面没有自旋轨道耦合修正．在这两个势能面上得到了碰撞能从0.1到1.4 eV的积分截面以及反应几率．对于Cl与D2反应，考虑自旋轨道耦合后由于势垒高度的增加反应截面向高能处有一个平移，但Cl与H2反应在低能处的反应活性反而增大了，原因是虽然自旋轨道耦合效应增加了势垒高度，同时减小了势垒宽度，隧道效应更加明显，而隧道效应在低能处起着比较重要的作用，所以反应活性比较大．当碰撞能大于0.7 eV时，没有考虑自旋轨道耦合时势垒高度较低，因而反应活性较大．     

Narrowband excitation of (2)H powder pattern and its application to (2)H 1D exchange sample-turning NMR.

Frequency-selective narrowband excitation of the (2)H powder pattern was examined. Selection of a single spectral band with a linewidth of ca. 15 kHz was achieved by a narrowband (1)H --> (2)H cross polarization by using the time-averaged precession frequency method. Further narrowing with a ca. 5 kHz linewidth is achieved by DANTE irradiation. The narrowband excitation was applied to transform a recently developed 2D spin-exchange method for obtaining structural information (Chem. Phys. Lett. 260, 159, (1996)) into its 1D analogue. The determination of the D-C-D bond angle was demonstrated for alpha-glycine-[2,2-d(2)]. Further, the intermolecular polarization transfer between two deuterons separated by 0.299 nm was detected with the mixing time of 500 ms.     

Coherent neutron scattering by light water (H2O) and a light-heavy water mixture (64 per cent H2O/36 per cent D2O)

Measurements have been made, with high statistical accuracy, of the differential scattering cross-section for 1·06 Å neutrons by light water and a special mixture of light and heavy water at 22°C. For light water, the structure in the scattering pattern is attributed mainly to coherent scattering; a structure factor has been obtained over a limited range of momentum transfer. For the chosen mixture, the protons and deuterons give no contribution to the coherent scattering and a structure factor has been obtained which corresponds very well to the oxygen-nucleus structure factor obtained from X-ray data. The results show the desirability of extending these high accuracy measurements using isotopic substitution methods as a means of obtaining the three partial structure factors for water. The method of isotopic mixtures is applicable to a wide range of proton containing liquids.     

Ag-SiO2复合薄膜形貌和吸收特性的研究

通过分层镀膜的方式制备Ag和SiO₂的分层结构，经过快速热退火后，Ag颗粒扩散到复合薄膜的表面附近. 通过改变Ag颗粒扩散的距离(SiO₂的膜厚)，可很好地控制Ag颗粒在复合薄膜表面附近的大小，浓度和形貌，进而对共振吸收特性产生影响. 在实验中，根据Ag颗粒扩散的长度来调节退火的时间. 发现经过足够长的时间(17.5min)后，Ag颗粒会形成平行于衬底的平面团簇. 由于Ag原子在平面团簇之间容易扩散，使得Ag颗粒的粒径平均值变小并趋于某一特定的半径，且粒径分布范围变小，导致吸收谱发生蓝移，吸收带变窄，且强度增加. 关键词： 复合薄膜 共振吸收 平面团簇     

Comparative analysis of diffuse reflection spectra and induced absorption spectra of ZrO2 micro- and nanopowders after irradiation with 100 keV electrons and protons

A comparative analysis of the structure, phase composition, morphology, and diffuse reflection spectra of zirconium dioxide micro- and nanopowders in the 0.2–2.5 μm range and the changes after irradiation with 100 keV electrons and protons is carried out. The reflective capability of nanopowders is found to be lower, though the radiation stability higher, as compared to micropowders.     

钪原子的自电离里德伯能级3d4s(~1D_2)nf~2D_(3/2),3d4s(~1D_2)nf~2F_(5/2)和3d4s(~1D_2)np~2D_(3/2)的理论研究

在多通道量子亏损理论框架下,利用相对论多通道理论,分别在冻结实近似和考虑偶极极化下计算钪原子的Jπ=(3/2)-,(5/2)-的三个收敛于[Ar]3d4s(1D2)的自电离里德伯系列的能级.对3d4s(1D2)np2D3/2和3d4s(1D2)nf2F5/2这两个系列,计算结果表明,考虑偶极极化效应后,理论计算和实验测量的量子数亏损之差普遍小于0.01.而对3d4s(1D2)nf2D3/2系列,考虑偶极极化效应后的结果和仅考虑冻结实的结果比较接近,理论计算和实验测量的量子数亏损之差普遍在0.04左右.     

Far-infrared absorption in H2 and H2-HE mixtures

Collision-induced absorption in the translation-rotation band of H₂ and H₂-He mixtures has been measured from 20 to 900 cm^-1 at 77.4, 195 and 292 K. To establish the accuracy of the results, various sources of error are investigated. The zeroth and first spectral moments are evaluated from experiment and theory for H₂ at the various temperatures. To obtain theoretical moments consistent with the experimental values, the quantum pair-distribution function must be used. The major portion of the experimental moments can be accounted for by quadrupole-induced dipoles in H₂ pairs. The remaining portion is attributable to an anistropic overlap interaction, although its magnitude depends on the value of the molecular parameters required to calculate the quadrupole contribution.     

Raman Scattering of H2O/D2O Solutions

The stretching vibrations of water are perfect characteristics of the hydrogen bond. Studying their frequency shift, changes of intensities, broadening of the bands and appearence of submaxima we can receive very important structural information about the groups involved in H-bonding and about the bond itself. The observed Raman spectra, however, are rather complicated because the OH and OD stretching bands are always superpositions of several bands due to intra- and intermolecular coupling, effect of Fermi resonance etc. The