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961.
DTA was used to study thermal properties and thermal stability of (50-x)Li2O-xTiO2-50P2O5 (x=0–10 mol%) and 45Li2Ot-yTiO2-(55-y)P2O5 (y=5–20 mol%) glasses. The addition of TiO2 to lithium phosphate glasses results in a non-linear increase of glass transition temperature. All prepared glasses crystallize
under heating within the temperature range of 400–540°C. The lowest tendency towards crystallization have the glasses with
x=7.5 and y=10 mol% TiO2. X-ray diffraction analysis showed that major compounds formed by annealing of the glasses were LiPO3, Li4 P2O7, TiP2O7 and NASICON-type LiTi2(PO4)3. DTA results also indicated that the maximum of nucleation rate for 45Li2O-5TiO2-50P2O5 glass is close to the glass transition temperature. 相似文献
962.
963.
Fourier Transform Infrared (FTIR) Spectroscopy has long been utilized as an analytical technique for qualitatively determining the presence of various different chemical bonds in gasses, liquids, solids, and on surfaces. Most recently, FTIR has been proven to be extremely useful for understanding the different types of bonding present in low dielectric constant “low-k” organosilicate materials. These low-k materials are predominantly utilized in the nanoelectronics industry as the interlayer dielectric material in advanced Cu interconnect structures. In this article, we utilize FTIR to perform a detailed analysis of the changes in chemical bonding that occur in Plasma Enhanced Chemically Vapor Deposited (PECVD) low-k a-SiC:H thin films. PECVD low-k a-SiC:H materials are equally important in advanced Cu interconnects and are utilized as both etch stop and Cu diffusion barrier layers. We specifically investigate the changes that occur in low-k a-SiC:H films as the dielectric constant and mass density of these films are decreased from > 7 to < 3 and from 2.5 to 1 g/cm3 respectively. We show that decreases in mass density and dielectric constant are accompanied by both an increase in terminal SiHx and CHx bonding and a decrease in SiC network bonding. At densities of 1.85 g/cm3, the concentration of terminal SiHx bonding peaks and subsequent hydrogen incorporation are achieved predominantly via terminal CH3 groups. Low-k a-SiC:H films with k < 3.5 and density < 1.3 g/cm3 can be achieved via incorporating larger organic phenyl groups but result in non-stoichiometric carbon rich films. Electron beam curing of these lower density a-SiC:H films results in volatilization of the phenyl groups leaving behind nanoporous regions and production of some CCC chain linkages in the network. 相似文献
964.
Various TiO2 nanostructures, such as nanorings, nanorods were synthesized via potentiostatic anodization of titanium powder under different conditions. The morphology of the obtained TiO2 nanostructures can be easily tuned by varying applied voltage. The crystal structure, compositional information and morphological structures were characterized by X‐ray diffraction (XRD), X‐ray photoelectron spectra (XPS) and field emission scanning electronic microscopy (FESEM). XRD and XPS analysis confirmed the anodization products were TiO2. A possible formation mechanism was suggested on the basis of the shape evolution of TiO2 nanostructures observed by FESEM. The results revealed that the applied voltage played an important role in the formation of various nanostructures. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
965.
S. Sebnem Cetin S. Corekci M. Cakmak S. Ozcelik 《Crystal Research and Technology》2011,46(11):1207-1214
Titanium dioxide (TiO2) thin film was deposited on n‐Si (100) substrate by reactive DC magnetron sputtering system at 250 °C temperature. The deposited film was thermally treated for 3 h in the range of 400‐1000 °C by conventional thermal annealing (CTA) in air atmosphere. The effects of the annealing temperature on the structural and morphological properties of the films were investigated by X‐ray diffraction (XRD) and atomic force microscopy (AFM), respectively. XRD measurements show that the rutile phase is the dominant crystalline phase for the film annealed at 800 °C. According to AFM results, the increased grain sizes indicate that the annealing improves the crystalline quality of the TiO2 film. In addition, the formation of the interfacial SiO2 layer between TiO2 film and Si substrate was evaluated by the transmittance spectra obtained with FTIR spectrometer. The electronic band transitions of as‐deposited and annealed films were also studied by using photoluminescence (PL) spectroscopy at room temperature. The results show that the dislocation density and microstrain in the film were decreased by increasing annealing temperature for both anatase and rutile phases. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
966.
Thermoelectric properties of a series of layered homologous rare-earth boron carbonitrides: HoB17CN, REB22C2N (RE=Y,Er,Lu), and YB28.5C4, were investigated. Samples for measurements were prepared in the form of hot pressed or isostatically pressed and annealed single phase polycrystalline powder. This series of compounds has structures where B6 octahedral and rare-earth atomic layers reside between an increasing number of B12 icosahedral and C-B-C chain layers, and has structural analogy to boron carbide. Interestingly, a variation from p-type thermoelectric behavior for YB28.5C4 to n-type for REB22C2N and HoB17CN was observed. This is the first non-doped compound among the boron-rich borides in which n-type thermoelectric behavior has been observed. Similar to other boron cluster compounds low values of the thermal conductivity κ were found. The origins of the low κ in such compounds has not been fully explained, but comparison among the homologous series shows that the thermal conductivity appears to increase as the number of boron cluster layers increases. This result indicates that the heavy rare-earth atoms residing in the boron matrix may play a role in depressing thermal conductivity in addition to other features common to boron cluster compounds. Although the absolute values of the determined figures of merit ZT are not large for hot pressed samples, the Seebeck coefficients and power factors for both n-type and p-type in this series show an increase at temperatures exceeding 1000 K. 相似文献
967.
The surface optical or Fuchs-Kliewer phonons of the (0 0 1) surface of 3C-SiC and the Si-terminated (0 0 0 1) surfaces of 4H- and 6H-SiC have been investigated with high resolution electron energy loss spectroscopy (HREELS). For each of the SiC polytypes the frequency of the surface optical phonon changes with surface reconstruction, indicating subtle differences in the static polarization at differently reconstructed surfaces. Due to their anisotropy, hexagonal surfaces exhibit a second, much weaker Fuchs-Kliewer mode. For all surfaces under examination, a linear dispersion of the Fuchs-Kliewer mode frequency has been found for wave vectors close to the -point. This dispersion can be explained by dynamical dipole coupling between atomic oscillators at the surface of the highly polar silicon carbide. 相似文献
968.
J. Eid J.L. Santailler B. Ferrand A. Basset A. Passero R. Lewandowska C. Balloud J. Camassel 《Superlattices and Microstructures》2006,40(4-6):201
Cubic-silicon carbide crystals have been grown from carbon-rich silicon solutions using the travelling-zone method. To improve the growth process, we investigated the effect of controlling more tightly some of the growth parameters. Using such improved growth conditions, our best sample is a 12 mm diameter and 3 mm long 3C–SiC crystal. It is grown on a (0001) 2 off, 6H–SiC seed and has 111-orientation. The low amount of silicon inclusions results in a reduced internal stress, which is demonstrated by the consideration of μ-Raman spectra collected at room temperature on a large number of samples. 相似文献
969.
孙亚娟 《吉林师范大学学报(自然科学版)》2012,(2):103-105,109
块体非晶合金由于具有优异的力学性能、物理性能、化学性能,从而得到广泛研究.本文综述了块体非晶合金室温力学行为研究的最新进展,详细介绍了块体非晶合金的室温塑性、屈服行为以及变性机制. 相似文献
970.
在一定反应温度范围内以熔盐为介质通过炭纤维与金属锆反应制备出碳化锆/锆涂层炭纤维,并在反应温度为800℃时,研究反应时间对碳化锆/锆涂层炭纤维表面相组成、形貌及其拉伸性能的影响。结果表明,800℃可制备均匀致密的碳化锆/锆涂层;且随着反应时间的延长,碳化锆/锆涂层厚度略有增加;涂层后炭纤维的拉伸强度和拉伸模量比原炭纤维的相应值略有减小。 相似文献