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Polycrystalline lead lanthanum titanate thin film having perovskite structure was fabricated by metalorganic deposition (MOD) on a ZrO[sub 2]/SiO[sub 2]/Si substrate at 600 °C for 1 h in O[sub 2] atmosphere. Columnar structured ZrO[sub 2] buffer layer was also prepared by a MOD process under the same condition. Electrical measurements were conducted on interdigitated electrodes. The crystalline structure and growth behavior of the films have been studied by x-ray diffraction and scanning electron microscopy. It is observed that dielectric response of the film is effected by the cable length used in the measurement and by the values of the ac voltage. Long cable gives rise to an additional resonance peak at high frequency caused by the stray inductance of the contacts and cables. The capacitance and loss tangent over low frequency range shows significant variations due to the trapped charges and space charges in the film. These variations are very dependent on the values of the ac voltage and the length of cable. Meanwhile, the trapped charges and space charges lead to abnormal P–E loops, in which the measured remanent polarization and coercive field increase with increasing frequency. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A study of the structure and in-plane dielectric properties of BaZr0.2Ti0.8O3 thin film epitaxially grown on (LaAlO3)0.3(Sr2AlTaO6)0.35 (001) single-crystal substrates through pulsed-laser deposition has been carried out. X-ray diffraction measurements revealed a good crystallinity and tensile in-plane stress in the film. Fine grains with an average size of ∼20 nm were observed using atomic force microscopy. Curie temperature of the film was found to be ∼120 °C, which is 100 °C higher than that of the ceramic. Butterfly-shaped C-V curve confirmed the in-plane ferroelectric state in the film. A large dielectric tunability of ∼50% was found in the film. [ABSTRACT FROM AUTHOR]

The evolutions of localized states, dielectric functions, and electronic band structure for nitrogen (N) incorporated GeTe (NGT) as functions of temperature (210-660 K) and N concentration (0%-18%) have been investigated with the aid of temperature dependent spectroscopic ellipsometry experiments. The increased Urbach absorption energy, caused by band-tail localized states, can be attributed to the increment of structure defects with N concentration, which is generated from the N atoms bonding with Ge. Besides, the details of the dynamic crystallization process and the role of nitrogen in NGT films have been elucidated by the abnormal behavior of interband transition energy and the evolutions of surface morphology, namely, the nitrides separation before crystallization and the inhibition on GT crystallization. The dynamic crystallization process and the nitrogen behavior in NGT are of great significance for further study on the reliability and endurance of the NGT-based data storage devices. [ABSTRACT FROM AUTHOR]

Tungsten (W) doping effects on Ge2Sb2Te5 (GSTW) phase change films with different concentrations (3.2, 7.1, and 10.8%) have been investigated by variable-temperature spectroscopic ellipsometry. The dielectric functions from 210 K to 660 K have been evaluated with the aid of Tauc-Lorentz and Drude dispersion models. The analysis of Tauc gap energy (Eg) and partial spectral weight integral reveal the correlation between optical properties and local structural change. The order degree increment and chemical bond change from covalent to resonant should be responsible for band gap narrowing and electronic transition enhancement during the phase change process. It is found that the elevated crystalline temperature for GSTW can be related to improved disorder degree. Furthermore, the shrinkage of Eg for GSTW should be attributed to the enhanced metallicity compared with undoped GST. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effects of inclusion of waste vinegar residue (WVR) in the diet of laying hens on chyme characteristics and gut microflora. A total of 96 60-wk-old Hy-Line Brown laying hens were selected and fed three diets including a corn and soybean meal-based control diet and two other diets with 20 g/kg and 40 g/kg of WVR. After 27 d feeding period, digesta was collected for protease activity, pH value and microflora determination. Bacterial genetic diversity was determined using DGGE analysis of the V3 region of 16S rDNA PCR products (230 bp) obtained from primers specific for the domain Bacteria. Inclusion of 20 g/kg and 40 g/kg of WVR in the diet decreased the digesta pH value in the gizzard (P=0.003) and increased pepsin activities in the gizzard of laying hens (P=0.032). Species of Enterobacter and Peptostreptococcaceae were more predominant in the cecum and ileum of laying hens, respectively. It is concluded that inclusion of 40 g/kg of WVR in the laying hen diet modifies intestinal pH value and pepsin activities in upper gastrointestinal tract and affects the lower gut microflora in laying hens. [ABSTRACT FROM AUTHOR]

The nano amorphous interface is important as it controls the phase transition for data storage. Yet, atomic scale insights into such kinds of systems are still rare. By first-principles calculations, we obtain the atomic interface between amorphous Si and amorphous Sb2Te3, which prevails in the series of Si–Sb–Te phase change materials. This interface model reproduces the experiment-consistent phenomena, i.e. the amorphous stability of Sb2Te3, which defines the data retention in phase change memory, and is greatly enhanced by the nano interface. More importantly, this method offers a direct platform to explore the intrinsic mechanism to understand the material function: (1) by steric effects through the atomic “channel” of the amorphous interface, the arrangement of the Te network is significantly distorted and is separated from the p-orbital bond angle in the conventional phase-change material; and (2) through the electronic “channel” of the amorphous interface, high localized electrons in the form of a lone pair are “projected” to Sb2Te3 from amorphous Si by a proximity effect. These factors set an effective barrier for crystallization and improve the amorphous stability, and thus data retention. The present research and scheme sheds new light on the engineering and manipulation of other key amorphous interfaces, such as Si3N4/Ge2Sb2Te5 and C/Sb2Te3, through first-principles calculations towards non-volatile phase change memory. [ABSTRACT FROM AUTHOR]

This paper reports on the integration and characterization of Pb(Zr,Ti)O 3 (PZT) thin film on silicon-on-insulator (SOI) wafers. Two perovskite-structured oxide layers, SrTiO 3 and (La,Sr)CoO 3 , were deposited by magnetron sputtering on the SOI to form a template and the bottom electrode. On the buffered SOI, the PZT thin film was deposited by sol-gel and spin coating techniques followed by thermal treatment for crystallization. X-ray diffraction revealed that PZT has a good quality of crystallization and a preferred orientation along the [001]-direction. The electrical measurement indicates that the PZT film on SOI has good ferroelectric and piezoelectric properties. The piezoelectric coefficient of the PZT film was found to be about 80× 10 - 12 m/V. [ABSTRACT FROM AUTHOR]

Rod-shaped and wire-shaped SnO2 nanowhiskers were synthesized by thermal evaporating of tin powders at 900 °C. Three Raman peaks (474, 632, 774 cm-1) showed the typical feature of the rutile phase of as-synthesized SnO2 nanowhiskers, which was consistent with the result of x-ray diffraction. A relatively low turn-on field of 1.37 V µm-1 at a current density of 0.1 µA cm-2 was obtained. The dependence of emission current density on the electric field followed a Fowler–Nordheim relationship. Our results indicated that SnO2 nanowhiskers had an interesting FE property as a wide band gap semiconductor. [ABSTRACT FROM AUTHOR]

The authors prepared Yb-doped bismuth iron oxide ceramics (Bi1-xYbxFeO3, with 0≤x≤0.20) by rapid liquid phase sintering method and investigated the material’s structures and electrical properties. The x-ray diffraction measurements showed that the doping of Yb has induced noticeable lattice distortion in the ceramics, and a largest distortion was observed when the concentration of Yb was 15%. By doping electrical resistivity, ferroelectric and dielectric properties of the ceramics were improved. Among all samples, BiFeO3 doped with 15% Yb was found to have the smallest leakage current density (<10-7 A/cm2) and the largest remnant polarization (8.5 μC/cm2) [ABSTRACT FROM AUTHOR]

SnO2 nanowires synthesized by thermal evaporation method are investigated as a possible anode electrode for Li-ion batteries. In the first discharge process, the capacity of Li ions is 2133 mA h g-1, which is much more than the theoretical total capacity of the bulk SnO2, 1494 mA h g-1. During the successive 15 cycles, the reversible capacity stays in the range of 1250–700 mA h g-1 with a capacity fading of 3.89% per cycle at a constant current density of 0.5 mA cm-2. These results demonstrate that SnO2 nanowires are a promising anode material for Li-ion battery applications. [ABSTRACT FROM AUTHOR]