采用SACVD改善器件电学性能

采用臭氧,正硅酸乙醋（O3/TEOS）基前驱物,通过次大气压化学气相沉积（SACVD）在深宽比高于8：1的STI和深宽比高于6：1的PMD应用中展现了优异的填充性能,并提高了器件的驱动电流,改善了PN结漏电。此外,在器件沟道区施加局部应力的方法也得到了证实。     

Multi-hop Multi-band Intelligent Relay-Based Architecture for LTE-Advanced Multi-hop Wireless Cellular Networks

In recent years, the cellular spectrum has become very crowded due to the tremendous success of mobile communications. However, a large portion of the electromagnetic spectrum assigned to other services is used sporadically only. A first step towards cognitive radio can be implemented in LTE-advanced networks by sensing the available frequencies and exploiting the existing radio spectrum opportunistically in order to improve its utilization. In this paper, novel multi-hop multi-band intelligent (MMI) radio architecture is proposed for LTE-advanced cellular networks that would make use of a number of intelligent gateways in order to enable simultaneous usage of spectrum resources within the same cell. It relies on a multi-band network model with increasing number of channels which exponentially reduces the time required for resource allocation. Importantly, an analytical model has been proposed to describe the effects of fading on optimum position of gateway. This model was found to have a very close match with the simulation results, in the calculation of mean, standard deviation and the statistically carried out $t$ tests. Further, the two-hop architecture provides a significant increase in the system capacity. With nine bands and 50 nodes in the network, the MMI based two-hop design provides up to 150 % higher than that offered by a single-hop cellular design and with up to 40 % higher than when a state-of-the-art two-hop routing technique is employed.     

Microwave-assisted route for synthesis of nanosized metal oxides

Microwave-assisted route for the synthesis of nanomaterials has gained importance in the field of synthetic technology because of its faster, cleaner and cost effectiveness than the other conventional and wet chemical methods for the preparation of metal oxide nanoparticles. In the present work, synthesis of metal oxide nanoparticles viz., γ-Fe₂O₃, NiO, ZnO, CuO and Co-γ-Fe₂O₃ were carried out by microwave-assisted route through the thermal decomposition of their respective metal oxalate precursors employing polyvinyl alcohol as a fuel. The metal oxide nanoparticles are then characterized for their size and γ to α (in γ-Fe₂O₃) transition and structure by employing powder X-ray diffraction (XRD) pattern, high-temperature X-ray diffraction (HTXRD) pattern and Fourier transform infrared (FT-IR) spectral studies. The morphology of the samples ranged from nanorods to irregular-shaped particles for different metal oxide samples on the basis of scanning electron microscopy and transmission electron microscopy images. Frequency-dependent dielectric study of the ferrite samples (γ-Fe₂O₃ and Co-Fe₂O₃) showed a similar behaviour, where the dielectric constant decreased rapidly with increase in frequency. Possible explanation for this behaviour is given.     

Influence of samarium doping on structural and dielectric properties of strontium bismuth tantalate ceramics derived by molten salt synthesis route

Layered Sr(Bi_1?xSm_x)₂Ta₂O₉ ceramics with x ranging from 0 to 0.10 (10 mol%) were fabricated by the low temperature molten salt synthesis route. X-ray powder diffraction studies revealed that the single phase orthorhombic layered perovskite structure is retained in all these compositions. Scanning electron microscopic studies on these ceramics confirmed the presence of well packed equiaxed plate shaped grains. The dielectric and electrical conductivity properties were studied in the 100 Hz–1 MHz frequency range at 300 K. Interestingly, the 10 mol% samarium doped SrBi₂Ta₂O₉ ceramics exhibited high dielectric constant (ε_r = 155) and low dielectric loss (0.00298) compared to those of other compositions. The electrical conductivity of undoped and samarium doped ceramics increased linearly with increase in frequency.     

Uses of α-Fe2O3 and fly ash as solid adsorbents

Solid adsorbents have shown great promise for control of particulate and non-particulate matter and as gas sensing devices in recent times. In the present study, adsorption of environmental toxic pollutant such as lead ions on solid adsorbents viz. α-Fe₂O₃ and fly ash, are reported. Considerable adsorption was observed on fly ash when compared to α-Fe₂O₃ surface. These studies are characterized by employing solid state and solution studies.     

Some magnetic properties of γ-Fe2O3 synthesized from ferrous fumarate half-hydrate

-Fe₂O₃ synthesized from ferrous fumarate half-hydrate was studied by measurements of D.c. electrical conductivity, Seebeck coefficient, initial magnetization and magnetic hysteresis, and by Mössbauer spectroscopy and scanning electron microscopy. The phase transformation observed by electrical conductivity measurements matched well with the phase transformation observed by the variation with temperature of initial magnetization measurements of -Fe₂O₃; this magnetic study also established the single-domain character of -Fe₂O₃. The magnetic hysteresis values of the -Fe₂O₃ synthesized indicated improved values over that of a -Fe₂O₃ sample synthesized by established procedures. The scanning electron micrographs showed that the -Fe₂O₃ particles were acicular in shape and the Mössbauer spectrum showed a well-resolved six-band spectrum. The presence of a hydrogen ferrite phase was also confirmed by the electrical and magnetic measurements.Deceased, 10 October, 1985.     

A Grüneisen Relation on Constant-Pressure Lines

Grüneisen's constant, γ, is ideally temperature-independent on constant-volume lines; a similar constant, λ, which is ideally temperature-independent on isobaric lines, has been found. The comparison between γ and λ shows that both expressions contain the ratio of the volumetric thermal expansion coefficient to the specific heat capacity; γ has an additional temperature dependence due to the thermal part of the compressibility, whereas λ has only a slight thermal component due to the volume per unit mass. λ has been chosen so that λ=γ at the point where the temperature and pressure are both zero. For most materials it is expected that λ≥γ with a different temperature dependence. It is shown empirically for a selection of ceramics that λ is nearly temperature-independent and has a value between 0.7 and 1.4.     

Spectral studies on cellulose treated with sodium deuteroxide

Cellulose II and cellulose I samples were treated respectively with a strong solution of sodium deuteroxide in D₂O and a 99% solution of ethylenediamine. The complexes were washed with D₂O and the nature of the OD bands were studied after rehydrogenating the sample. The infrared spectra of these rehydrogenated samples showed well-resolved OD bands which are resistant to reexchange. The Characteristic bands are discussed and compared with the predicted OH-OD frequency shifts.     

Thermal stability, microstructure and crystallization kinetics of melt-spun Zr-Ti-Cu-Ni metallic glass

Melt-spun Zr_63.33Ti_8.89Cu_15.45Ni_12.33 glassy ribbons display a double-step devitrification behavior characterized by the precipitation of a metastable quasicrystalline phase in the first stage of the crystallization process, followed by the formation of crystalline phases in the following crystallization event. Investigation of the crystallization kinetics reveal that the initial part of the glass-to-quasicrystalline transformation (x ≤ 55 vol.%) occurs by diffusion controlled growth with an increasing nucleation rate (Avrami exponent n ≥ 2.5), whereas the later stage of the transformation (x > 55 vol.%) is dominated by the growth of the formed nuclei rather than by the generation of new nuclei (2.0 ≤ n ≤ 2.5). The activation energy for quasicrystallization is 360 kJ/mol, which is comparable to the values reported for other quasicrystal-forming Zr-based metallic glasses.