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61.
M. Ahmad P. Kumar N. Suri J. Kumar R. Thangaraj 《Applied Physics A: Materials Science & Processing》2009,94(4):933-937
The crystallization kinetics of Sn10Sb20−x
Bi
x
Se70 (x=0,2,4,6,8) chalcogenide system has been studied. Crystallization studies using differential scanning calorimetry under nonisothermal
conditions with different heating rates are reported. The glass transition temperature is found to increase with the increase
in heating rate as well as with the addition of bismuth. The apparent activation energy for glass transition and that for
crystallization have been determined using the Kissinger equation. Thermal stability and glass forming tendency have also
been studied. 相似文献
62.
Chung-Jen Chung Ying-Chung Chen Chien-Chuan Cheng Kuo-Sheng Kao 《Applied Physics A: Materials Science & Processing》2009,94(2):307-313
This study investigates c-axis tilted aluminum nitride (AlN) piezoelectric films for the improvement of both shear and longitudinal
acoustic wave resonances. Solidly-mounted resonator (SMR) structure is adopted for the applications of high frequency wireless
communications and high sensitivity sensors. As to the piezoelectric layer, c-axis tilted AlN has the capability to excite
the dual-mode resonances, namely, the longitudinal and shear mode resonances. In this study, SMR devices made with a seven-layer
molybdenum/silicon dioxide (Mo/SiO2) Bragg reflector and the c-axis tilted AlN are carried out. A conventional off-axis sputtering technique is applied to grow
the tilted AlN.
The outcome frequency responses show dual resonant characteristics. However, the longitudinal resonance fades away with the
AlN c-axis tilted angle, and the quality factor of the longitudinal resonance decreases. Consequently, we make an improvement
by tilting the off-center substrates toward the sputtering source and successfully enhance the longitudinal resonance while
preserving the shear resonance at the same time. Not only the shear resonance for the liquid-based sensing application, but
also an outstanding longitudinal resonance could be obtained. The practicability of the dual-mode resonator is extended. 相似文献
63.
D. A. Drabold 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,68(1):1-21
In this Colloquium, I describe some current frontiers in the physics of semiconducting amorphous materials and glasses, including
a short, but self-contained discussion of techniques for creating computer models, among them the quench from the melt method,
the Activation-Relaxation Technique, the decorate and relax method, and the experimentally constrained molecular relaxation
scheme. A representative study of an interesting and important glass (amorphous GeSe3:Ag) is provided. This material is a fast-ion conductor and a serious candidate to replace current FLASH memory. Next, I discuss
the effects of topological disorder on electronic states. By computing the decay of the density matrix in real space, and
also computing well-localized Wannier functions, we close with a quantitative discussion of Kohn’s Principle of Nearsightedness in amorphous silicon. 相似文献
64.
R. Plasil I. Korolov T. Kotrik P. Dohnal G. Bano Z. Donko J. Glosik 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(2):391-398
Experimental studies of the electron energy distribution function “EEDF” under well defined conditions in flowing afterglow
plasma, using a Langmuir probe are reported. The EEDF is measured in He2
+ and Ar+ dominated plasmas and in XeH+ and XeD+ dominated recombining plasmas. He is used as a buffer gas at medium pressures in all experiments (1600 Pa, 250 K). The deviation
of the measured EEDF from Maxwellian distribution is shown to depend on plasma composition and on the processes governing
the plasma decay. The influence of energetic electrons produced during the plasma decay on the body and tail of the EEDF is
observed. The mechanism of energy balance in afterglow plasma is discussed. 相似文献
65.
ZnO nanospheres are synthesized by a two-step self-assembly method. X-ray diffraction pattern and Raman scattering spectra measurements show that all the samples present a typical wurtzite structure. A regular sphere shape is inspected by field emission scanning electron microscope and transmission electron microscope for the samples. It is shown that the as-synthesized ZnO nanosphere is composed of numbers of primary particles with size of around 1Ohm. A possible growth mechanism for the two-step self-assembly ZnO nanosphere is proposed. After applying the ZnO nanospheres to dye-sensitized solar cells (DSSCs), a 117% increase of the overall light to electricity conversion efficiency η is observed compared with that of the ZnO nanopartieles based DSSCs. Associated with the UV-vis results, light scattering is assigned to the great improvement of η. 相似文献
66.
A focused as opposed to collimated light beam is typically used as probe in order to achieve a smaller as well as more intense light interrogation area in spectroscopic ellipsometry of thin films. In this work, we performed geometric ray analysis at the illumination and recording ends of such a system. The numerical results revealed substantial changes in (i) average optical path length and (ii) optical path length differences, which varied according to wavelength despite the film thickness remaining uniform. These results were able to consistently explain the anomalies found when different focus probe beam sizes were used in experimental spectroscopic ellipsometry measurements. 相似文献
67.
二噁英、多溴联苯醚和多氯联苯同时测定方法的研究 总被引:1,自引:0,他引:1
本实验以美国环保署1613B、1614和1668A等标准方法为基础,建立了同一样品中二噁英、多溴联苯醚和多氯联苯的同位素稀释-多层色谱柱净化-高分辨气质联用-高通量同时分析方法.该方法利用弗罗里土对二噁英组分吸附能力强的特点,采用不同极性的溶剂淋洗,先实现二噁英组分和其它两个组分的分离,再利用多溴联苯醚更易保留在硝酸银硅胶(10%)柱上的特点,实现了多溴联苯醚和多氯联苯两类化合物的分离.实验优化了样品前处理过程,纯化过程中去除了大量干扰物质,同时将三类化合物在前处理中进行分离,消除了相互干扰,实现了准确定量.纯化效果和检测限均符合美国环保署相关标准的要求.通过标准参考物的比对和实际样品的分析验证了方法的可靠性和结果的准确性. 相似文献
68.
M.A. García-Sánchez M.L. Estrada-Rico M.I. Coahuila-Hernández S.R. Tello-Solís A. Campero 《Journal of Non》2009,355(2):120-181
We study the influence of the nature and ring positioning of amino, hydroxy, and carboxy substituent groups on the fluorescence and some other physicochemical properties of free (H2TPP) and metalled tetraphenylporphyrins (MTPP). Furthermore, we have studied the feasibility of covalently bonding TPP species on the surface of the pores of a silica matrix prepared by the sol-gel method through the bridging action of either one of the following functionalized alkoxides: 3-isocyanatopropyltriethoxysilane, (IPTES) or 3-aminopropyltriethoxysilane (APTES). Importantly, the red fluorescence observed in free porphyrin solutions is preserved even after the macrocyclic species is covalently bound to the silica matrix. The formation of a chemical union between the porphyrin substituting groups and the organic groups of the IPTES or APTES alkoxides render the H2P-f precursory species has been proved successful by FTIR spectroscopy; likewise, the bond between Si-OH groups on the silica surface and the H2P-f has been made evident. The best results, in terms of fluorescence preservation, are obtained by using a TPP substituted with -NH2 groups in the ortho position of the phenyl rings, i.e. H2T(o-NH2)PP. A comparative fluorescence study of xerogels physically grafted or covalently bound with the latter TPP species confirm that, in the first case, the interaction of the molecule with the silanol groups of the silica surface of the gel inhibits fluorescence; while in the second case fluorescence is preserved. 相似文献
69.
We report on the effect of BaO on the crystallization kinetics of glasses in the diopside (CaMgSi2O6)-Ca-Tschermak (CaAl2SiO6) system. Partial substitution (i.e. 5%, 10% and 20%) of Ba2+ for Ca2+ was attempted in composition CaMg0.8Al0.4Si1.8O6, in three different glasses while partial substitution of B3+ for Al3+ was made in the fourth glass. Structural investigations on the glasses have been made by density measurements, molar volume and Infra-red spectroscopy (FTIR). Non-isothermal crystallization kinetic studies have been employed to study the mechanism of crystallization in all the four glasses. The Avrami parameter for the glass powders is ∼2, indicating the existence of intermediate mechanism of crystallization. Crystallization sequence in the glasses has been followed by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and FTIR. Augite crystallized out being the dominant phase in all the glass-ceramics, while different polymorphs of BaAl2Si2O8 were present as secondary or minor phases. 相似文献
70.
This study highlights the role of two platinum-group metals, ruthenium and palladium, in the redox equilibria of nuclear waste containment glass. Electrochemical measurements in simplified R7/T7 glass melts were used to develop a thermodynamic model of ruthenium redox equilibrium. The oxygen fugacity at equilibrium, corresponding to the coexistence of ruthenium oxide and ruthenium metal dispersed in the molten glass, was measured at different ratios at temperatures ranging from 1000 °C to 1200 °C. Experiments were carried out on glass with and without Pd, revealing the combined role of palladium and tellurium on redox equilibria in the glass. The formation of palladium-tellurium alloys in nuclear glass was observed to result in oxidation of the elements dissolved in the melt. 相似文献