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Na(DxH1-x)3(SeO3)2 single crystals were grown with a deuterium content of 37%, and the spectra and relaxation times of the 2H and 23Na nuclei in the mixed Na(D0.37H0.63)3(SeO3)2 crystals were measured as functions of temperature. The 2H and 23Na nuclear magnetic resonance (NMR) spectra undergo changes near 213 K. Our 23Na NMR results for x≥0.3 show that there is no triclinic intermediate phase; the paraelectric α-phase and ferroelectric γ-phase arise in mixed Na(D0.37H0.63)3(SeO3)2 crystals. In addition, the 2H and 23Na relaxation times of mixed Na(D0.37H0.63)3(SeO3)2 crystals are different from the 2H and 23Na relaxation times of NaH3(SeO3)2 and NaD3(SeO3)2. The effects of partial deuteration of sodium trihydrogen selenite crystals include not only a shift in the phase transition temperature TC but also a change in the local symmetry. [ABSTRACT FROM AUTHOR]

Pb(Zr 0.52 Ti 0.48 )O 3 thin films were fabricated on Pt/Ti/SiO 2 /Si substrates by the sol-gel method. A UV-photolysis process was added before the final annealing of the coated films. This UV-photolysis process made it possible to lower the crystallization temperature and to stabilize the film surface and interface during the annealing process. The UV-photolysis-processed PZT thin films exhibited enhanced ferroelectricity and a lower leakage current density than the non-treated ones. It is thought that the UV-treatment process is a very effective in enhancing ferroelectric and electrical properties for the ferroelectric random access memory device applications. [ABSTRACT FROM AUTHOR]

The article discusses a study on the ß-cyclodextrin catalyzed oxidation of aldehydes to the corresponding carboxylic acids using aqueous hydrogen peroxide. Topics covered include a method for the oxidation of aldehydes to carboxylic acids in the absence of any expensive and hazardous reagents, the oxidation of benzaldehyde to benzoic acid, and the oxidation of inactive aliphatic aldehydes.

Oxygen-deficient BaTiO3-δ exhibits an insulator-metal transition with increasing δ. We performed neutron total scattering measurements to study structural evolution across an insulator-metal transition in BaTiO3-δ. Despite its significant impact on resistivity, slight oxygen reduction (8 = 0.09) caused only a small disturbance on the local doublet splitting of Ti-O bond. This finding implies that local polarization is well preserved under marginal electric conduction. In the highly oxygen-deficient metallic state (δ = 0.25), however, doublet splitting of the Ti-O bond became smeared. The smearing of the local Ti-O doublet is complemented with long-range structural analysis and demonstrates that the metallic conduction in the highly oxygen-reduced BaTiO3-δ is due to the appearance of nonferroelectric cubic lattice. [ABSTRACT FROM AUTHOR]

We have investigated variations of the spectroscopic composition due to thermal mixing on the surface and at the interface by thermal annealing of Pt/Ti and Pt/TiOx electrodes. We also have studied in detail, reaction and diffusion mechanism of these elements through the film for each separate electrode type. The electrode stacks were annealed by the rapid thermal annealing (RTA) system. Auger electron spectroscopy (AES) technique was used to investigate surface elemental distribution and depth profiles. We have also discussed morphological and structural behavior of these films. [ABSTRACT FROM AUTHOR]

We have measured the temperature dependences of the optical polarizing microscopy and the stress-strain hysteresis curves in the K3H(SO4)2,Rb3H(SO4)2, and (NH4)3H(SO4)2 crystals grown by using the slow evaporation method. From these temperature dependences, it was determined that the three single crystals undergo the ferroelastic phase transitions near Tc. We also studied the ferroelastic domain switching that occurs in the three single crystals due to external mechanical stress. The critical stress values for switching from the ferroelastic twin domain to the paraelastic single domain were obtained. The ferroelastic domain switching stress of Rb3H(SO4)2 crystals (0.7 MPa) was found to be higher than those of K3H(SO4)2 and (NH4)3H(SO4)2 crystals (0.3 and 0.25 MPa, respectively). (NH4)3H(SO4)2 and K3H(SO4)2 can therefore be more easily transformed by a weak external mechanical stress. This domain switching from the ferroelastic twin domain to the paraelastic single domain is explained by the restriction of the rotation of the SO4 tetrahedron by the external stress. [ABSTRACT FROM AUTHOR]

By combining high-throughput experiments and first-principles calculations based on the DFT-ACBN0 approach, we have investigated the energy band gap of Sr-, Pb-, and Bi-substituted BaSnO3 over wide concentration ranges. We show that the band gap energy can be tuned from 3 to 4 eV by chemical substitution. Our work indicates the importance of considering the mixed-valence nature and clustering effects upon substitution of BaSnO3 with Pb and Bi. Starting from the band gap of ~3.4 eV for pure BaSnO3, we find that Pb substitution changes the gap in a nonmonotonic fashion, reducing it by as much as 0.3 eV. Bi substitution provides a monotonic reduction but introduces electronic states into the energy gap due to Bi clustering. Our findings provide new insight into the ubiquitous phenomena of chemical substitutions in perovskite semiconductors with mixed-valence cations that underpin their physical properties. [ABSTRACT FROM AUTHOR]

Solution studies have proposed that crystal nucleation can take more complex pathways than previously expected in classical nucleation theory, such as formation of prenucleation clusters or densified amorphous/liquid phases. These findings show that it is possible to separate fluctuations in the different order parameters governing crystal nucleation, that is, density and structure. However, a direct observation of the multipathways from aqueous solutions remains a great challenge because heterogeneous nucleation sites, such as container walls, can prevent these paths. Here, we demonstrate the existence of multiple pathways of nucleation in highly supersaturated aqueous KH2PO4 (KDP) solution using the combination of a containerless device (electrostatic levitation), and in situ micro-Raman and synchrotron X-ray scattering. Specifically, we find that, at an unprecedentedly deep level of supersaturation, a highconcentration KDP solution first transforms into a metastable crystal before reaching stability at room temperature. However, a low-concentration solution, with different local structures, directly transforms into the stable crystal phase. These apparent multiple pathways of crystallization depend on the degree of supersaturation. [ABSTRACT FROM AUTHOR]

Copper (Cu) thin films have been widely used as electrodes and interconnection wires in integrated electronic circuits, and more recently as substrates for the synthesis of graphene. However, the ultra-high vacuum processes required for high-quality Cu film fabrication, such as molecular beam epitaxy (MBE), restricts mass production with low cost. In this work, we demonstrated high-quality Cu thin films using a single-crystal Cu target and radio-frequency (RF) sputtering technique; the resulting film quality was comparable to that produced using MBE, even under unfavorable conditions for pure Cu film growth. The Cu thin film was epitaxially grown on an Al2O3 (sapphire) (0001) substrate, and had high crystalline orientation along the (111) direction. Despite the 10-3 Pa vacuum conditions, the resulting thin film was oxygen free due to the high chemical stability of the sputtered specimen from a single-crystal target; moreover, the deposited film had > 5 x higher adhesion force than that produced using a polycrystalline target. This fabrication method enabled Cu films to be obtained using a simple, manufacturing-friendly process on a large-area substrate, making our findings relevant for industrial applications. [ABSTRACT FROM AUTHOR]

We report the successful melting and high-temperature liquid density measurements of grain-free single copper and silver crystals, using electrostatic levitation (ESL), for the first time. The melting of Cu and Ag using ESL has not been reported to date due to the unusual charge instability of these samples at high temperatures. We report here an improved levitation stability during heating when using single-crystal specimens. These results will aid the development and further study of industrially important Cu- and Ag-based materials, by indicating the key physical properties of their liquid phases. [ABSTRACT FROM AUTHOR]

Resistivity is an intrinsic feature that specifies the electrical properties of a material and depends on electron-phonon scattering near room temperature. Reducing the resistivity of a metal to its potentially lowest value requires eliminating grain boundaries and impurities, but to date few studies have focused on reducing the intrinsic resistivity of a pure metal itself. We could reduce the intrinsic resistivity of single-crystal Ag, which has an almost perfect structure, by impurity doping it with Cu. This paper presents our results: resistivity was reduced to 1.35 μΩcm at room temperature after 3 mol% Cu-doping of single-crystal Ag. Various mechanisms were examined in an attempt to explain the abnormal behavior. [ABSTRACT FROM AUTHOR]

We report the fabrication of a biofield-effect protein-sensor (BioFEP) based on atmospheric-pressure plasma (AP) treatment of a conducting polyaniline (PANI) film. Successive H2 and O2 AP (OHAP) treatment generated dominant hydrophilic -OH and O=CO- functional groups on the PANI film surface, which served as strong binding sites to immobilize bovine serum albumin (BSA) protein molecules. The output current changes of the BioFEP as a function of BSA concentration were obtained. The resistance of the OHAP surface could be sensitively increased from 2.5×108 ... to 2.0×1012 ... with increasing BSA concentrations in the range of 0.025-4 μg/ml. The results suggest that the method is a simple and cost-effective tool to determine the concentration of BSA by measuring electrical resistance. [ABSTRACT FROM AUTHOR]

We investigated the effects of Al doping on ferromagnetism in Co-doped ZnO and the mechanisms that give rise to ferromagnetism in hydrogen-injected ZnCoO. The aim of this study was to determine whether the occurrence of ferromagnetism or the strength of the magnetization is related to the charge carrier mobility, charge carrier density, or the presence of defects in the crystal lattice. Al doping increased the carrier density, as well as the density of oxygen vacancies and the lattice strain; however, these physical properties were not related to the changes in magnetism. Al-doped and undoped ZnCoO showed an increase in ferromagnetism as a function of the hydrogen plasma treatment time. Al doping suppressed the hydrogen-mediated ferromagnetism in ZnCoO:H by trapping hydrogen via oxygen vacancies created by Al doping. [ABSTRACT FROM AUTHOR]

Based on hydrogen-mediated ferromagnetism and a selective hydrogen exposure technique, i.e., hydrogen lithography, we attempted to produce magnetic domains in a paramagnetic host. Hydrogen lithography on Co-doped ZnO with an anodic aluminum oxide template was used to produce nanomagnetic domains in paramagnetic Co-doped ZnO. The domains showed in-plane magnetization with a head-to-tail configuration at room temperature, which is consistent with the object-oriented micro-magnetic framework simulations. [ABSTRACT FROM AUTHOR]

Using a single-crystal wire fabricated through the crystal growth process, the contribution of grain boundaries (GBs) to electrical resistivity was investigated in copper. We developed a novel wire fabrication process that preserved the grain-free structure of single-crystal copper (SCC) grown by the Czochralski method. The resistivity of grain-free SCC showed a reduction of 9% compared to the international annealed copper standard (IACS) resistivity, with the resulting value smaller than that of silver. We also found that the GBs strongly influenced the resistivity above 70 K, but hardly contributed below 70 K, unlike the impurities. Insights into the GB effects could contribute to our understanding of conducting phenomena and the development of nanoscale analytical models. [ABSTRACT FROM AUTHOR]

This paper presents complex dielectric properties of ferroelectric BSTO thin film, deposited on MgO substrate by pulsed laser deposition, in the frequency range of 0.5 ∼ 3.0 THz using terahertz time-domain spectroscopy (THz-TDS). In order to extract complex dielectric properties of the thin film, multiple reflections within the thin film were considered and an error function between the calculated and measured data was introduced. The real part of the dielectric constant of the BSTO thin film was less than 170 and the dielectric loss tangent of the BSTO thin film varied between 0.9 and 3.0. All values of an error function were less than 7 × 10- 4 in the measured frequency ranges. The analysis method using THz-TDS enables us to find out complex dielectric properties of ferroelectric thin film exactly. [ABSTRACT FROM AUTHOR]

A new type of CNTs based ammonia gas sensor was investigated. The array of carbon nanotubes was synthesized into the pore of anodized aluminum oxide (AAO) by thermal chemical vapor deposition method without metal catalyst. The anodized aluminum oxide was synthesized on the p–type Si(100) substrates by two step anodization process. After removing the carbon top layer, a thin Ag electrode was deposited on the surface of sample to get the opened end of the CNTs for gas sensor. The electrical and gas sensing properties of carbon nanotubes based sensor were characterized by I-V test after metal deposition on the top of carbon nanotubes. The device shows high sensitivity for detecting the NH3 gas at room temperature. [ABSTRACT FROM AUTHOR]

Acceptor dopants prevent the reduction of Ti 4+ to Ti 3+ by neutralizing the donor action of the oxygen vacancies. Bi 3.6 La 0.4 Ti 3 O 12 thin film has a low dielectric constant and the smallest dielectric loss among La-modified bismuth titanate materials. We grew Bi 4.3 Ti 3 O 12.4 , Bi 3.65 La 0.47 Ti 3 O 12.17 and Mn-doped Bi 3.65 La 0.47 Ti 3 O 12.17 crystals. The remanent polarization of Mn-doped Bi 3.65 La 0.47 Ti 3 O 12.17 crystal indicated a higher value, and the coercive field indicated a lower value. From the XPS results, we suggested that oxygen vacancies of Bi 3.65 La 0.47 Ti 3 O 12.17 might be decreased with Mn doping. The band gap of the crystals was about 3.11, 3.25 and 3.2 eV for Bi 4.3 Ti 3 O 12.4 , Bi 3.65 La 0.47 Ti 3 O 12.17 and Mn-doped Bi 3.65 La 0.47 Ti 3 O 12.17 crystals, respectively. [ABSTRACT FROM AUTHOR]

Cerium-modified Bi4Ti3O12 thin films were deposited on GaN substrates by the pulsed laser deposition method. The substrate temperature was varied from 600°C to 750°C in 50°C steps. The surface topographies and orientations of the Bi0.4Ce0.6Ti3O12 (BCeT) films were gradually changed in proportion to the substrate temperature. The diffusion reaction between BCeT and the GaN layer and the depth profiles of the films were investigated by Auger electron spectroscopy (AES), The ferroelectric properties and leakage current characteristics of the metal-ferroelectric-GaN stacked thin films were measured and discussed. [ABSTRACT FROM AUTHOR]

The Pb(Zr0.52Ti0.48)O3 thin films were fabricated by sol-gel method. A modified pyrolysis method, such as UV-photolysis process, was adapted before final annealing of the films. The UV-photolysis processed PZT thin films exhibited enhanced ferroelectricity (Pr) and lower leakage current density than not-treated one. UV-photolysis process also made it possible to lower the crystallization temperature and to stabilize film surface and interface. The interface states were characterized by Auger electron spectroscopy (AES). The fatigue and retention test were also examined. It is thought that the UV-treatment process is very effective to enhance ferroelectric and electrical properties for ferroelectric random access memory device applications. [ABSTRACT FROM AUTHOR]

Photoluminescence(PL) of SrTiO 3 :Pr system was investigated. Nanocrystalline powders of SrTiO 3 :Pr prepared by sol-gel method show red emission at 611nm under UV excitation. The photoluminescence intensity depends on grain(particle) size, annealing temperature, thermal annealing time and mol concentration of activator. The photoluminescence properties have been investigated under various preparation conditions and compositions. Based on the emission intensity, the concentration of activator was optimized. The maximal intensity of PL was obtained at 0.2mol% of Pr. Properties of PL versus annealing conditions, mol concentration and various doping material were experimentally examined. [ABSTRACT FROM AUTHOR]

ZnO nanobarbed fibers (NBFs) are synthesized by the epitaxial growth of 1-D ZnO nanorods (NRs) on ZnO nanofibers (NFs) via electrospinning and chemical bath deposition. The change in resistance of the NBFs in the presence or absence of a gas was explained using the surface depletion model and modified grain boundary model, in which the junction points of the NFs and NRs are considered. The NBF structure showed extraordinary NO2 sensing performance for gas concentrations up to 30 ppb. This indicates that NBF structures have great potential for use as gas sensing materials. [ABSTRACT FROM AUTHOR]

Through a simple post hydrogen plasma treatment, we show the strong inducement of the room temperature ferromagnetism in Zn0.9Co0.1O:H nanocrystals fabricated by sol-gel process. X-ray diffraction, high resolution transmission electron microscopy, and neutron high resolution powder diffraction measurements of Zn0.9Co0.1O nanocrystals before and after hydrogenation process confirmed that there are no structural changes in nanocrystal and any creation of magnetic secondary phase. Nevertheless, the clear ferromagnetic hysteresis loop of the hydrogenated Zn0.9Co0.1O nanocrystal was observed in superconducting quantum interference device. These results indicate that the ferromagnetism can be derived from a short-range spin ordering by hydrogen mediation in Co doped ZnO. [ABSTRACT FROM AUTHOR]

(201)-oriented β-Ga2O3/GaN thin films were epitaxially grown by pulsed laser deposition. These films have the specific in-plane orientation, which was confirmed by φ scans of Ga2O3 (111) and (311) reflections. When oxygen flow rate was increased, the surface morphologies and roughness of β-Ga2O3 drastically changed. The β-Ga2O3/GaN structure showed a stable and sharp interface and uniform elemental distribution in depth. The dielectric constant and memory window of β-Ga2O3/GaN were about 13.9 and 0.50 V for oxygen flow rate of 5 SCCM (SCCM denotes cubic centimeter per minute at STP). [ABSTRACT FROM AUTHOR]

Temperature changes induced by externally applied mechanical stress were observed in the Pb3(PO4)2 ferroelastic crystal. These characteristic features can be explained by the thermoelastic effect as in other thermoelastic martensitic materials. In this study, the mechanical stress dependence of the thermoelastic effect was studied using a modified thermomechanical analysis system. The thermoelastic effect strongly depended on the mechanical stress and was enhanced by ferroelastic domain switching, responsible for the pseudoelastic behavior of ferroelastic materials. The ∂T/∂σsin, the change of sample temperature with varying stress enhanced by pseudoelasticity, was ∼9.5×10-2 °C/MPa at 159 °C, ferroelastic temperature region under 1.2 MPa sinusoidal stress. This value is eight to nine times higher than the values obtained under bias stress. This result can be explained by a thermoelastic equation which includes the effective thermal expansion coefficient in the ferroelastic phase. [ABSTRACT FROM AUTHOR]

K-doped ZnO films were prepared on Al2O3(0001) substrates by solution deposition. For the prepared thin films of Zn1-xKxO (x=0.002, 0.01, 0.02, 0.05, 0.1), we carried out x-ray diffraction, transmittance spectroscopy, photoluminescence, Hall measurement and x-ray photoemission spectroscopy study, and found that properties like the crystallinity, optical band gap, carrier concentrations and chemical binding states changed at a K doping concentration of 2 mol %. From these results, we suggest that the doped K in ZnO films processed by the sol–gel method plays a different role at K doping concentrations below 2 mol % and above 2 mol %. [ABSTRACT FROM AUTHOR]