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Single-crystalline Bi nanowires were studied to determine temperature dependence.

Ballistic electronic transport in a mesoscopic structure-quantum cable was theoretically studied.

Chemical coprecipitation was used to prepare the nanopowders of Bi2Ti2O7 with different Na+ modifications. After sintering at high temperatures, their phase structures were transformed into a solid solution of Bi4Ti3O12 and Bi2Ti4O11. Dielectric peak at 517 degrees Celsius in Bi4Ti3O12 develops from the ferroelectric domain transformation and shifts to a higher temperature with rising Bi2Ti4O11 concentration. Further, high dielectric values are produced by the multiple relaxation processes and the mechanism is shut off at a dc bias Ec. The results indicate that the P-E hysteresis loop measurements has a superior ferroelectricity in the solid solution.

A novel method in the preparation of Bi4Ti3O12 nanoparticles is presented. The nanoparticles were synthesized by chemical coprecipitation and crystallized in the perovskite structure after calcining at 520 degrees C and the dielectric characteristics were calculated in bulk nanocrystalline compacts with different grain sizes. Results reveal that there were three peaks in the curves of the dielectric response as a function of temperature.

A new study investigates the optical properties of mesoporous silica molecular sieves.

A study was conducted to examine the effects of photoluminescence on SiO2 aerogels prepared by a sol-gel technique and supercritical drying. The heat treatment states of the assemblies were also analyzed after immersion in aqueous solutions of ZnSO4 and NH4OH. Results showed a very strong photoluminescence band supporting a peak position of about 500 nm. Findings also indicated that the luminescence intensities of the assemblies were 10 to 50 times higher than that of nanostructured ZnO bulks.

The dc resistivity and its temperature behavior in nanostructured n-NiAl samples were examined at a temperature range of 77-300 K using the four-probe technique. The results, which may be explained by dominant grain boundary scattering indicated a proportional relation between dc resistivity and temperature for n-NiAl with relative densities above 70%. Densities below 68-70%, however, resulted in negative temperature coefficient of resistivities indicative of nonmetallic behavior.

The x-ray photoelectron spectroscopy technique is employed to explain the different interfacial, as well as the optical properties of the HfTiO thin films with different Ti concentrations. An increase in the Ti concentration is shown to lead to a significant reduction in the band gap of the thin films.

Spectroscopic ellipsometry (SE) and x-ray photoelectron spectroscopy are used for examining the thickness-modulated optical dielectric constants and band alignments of Hf[O.sub.x][N.sub.y] films grown by sputtering. The suitable optical dielectric constants and band offsets relative to Si have made sputtering-derived Hf[O.sub.x][N.sub.y] film a very good candidate for high-k gate dielectrics.

X-ray photoemission spectroscopy and spectroscopy ellipsometry (SE) are employed to study composition-dependent electronic structure and optical properties of [Hf.sub.1-x][Si.sub.x][O.sub.y] gate dielectrics on Si at 450 degree Celsius. The results suggested that the [Hf.sub.1-x][Si.sub.x][O.sub.y] film offer sufficient tunneling barriers for electrons and holes to apply them as potential candidates as alternative gate dielectrics.

The effects of postdeposition annealing on the structure and optical properties of high-k gate dielectric Y[O.sub.x][N.sub.y] films grown by reactive sputtering are examined. The results suggested that the optical band gap of Y[O.sub.x][N.sub.y] films shifts to higher energy after higher temperature annealing due to the reduction on N content and the change of crystalline structure in Y[O.sub.x][N.sub.y] films.

We propose that quantum cables can be used as a kind of transport spectroscope to obtain directly the quasi-one-dimensional (Q1D) density of states (DOS) of cylindrical quantum wires. By simultaneously measuring the direct current through the cylindrical quantum wire and the leaky tunneling current into its neighboring wire at desirable temperatures, one can obtain detailed information about the Q1D DOS and subband structure of the cylindrical quantum wire. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]