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Ultra-sensitive H2S sensors operated at room temperature were fabricated using Ag-In2O3 nanorod composites synthesized using sol-hydrothermal method followed by NaBH4 reduction process. TEM proved that the In2O3 was nanorod structures of ~ 110 nm in length and ~ 35 nm in diameter. Ag nanoparticles with diameters from 10 to 15 nm homogeneously decorated on the surfaces of the In2O3 naonorods. XRD and XPS analysis proved that the Ag elements existed as zero-valent metallic silver on the surface of the In2O3 nanorods. Ag nanoparticles could enhance the formation of chemisorbed oxygen species and interactions between H2S molecules and oxygen species due to spillover effect, and the electron transfer between Ag and In2O3 nanorods also enhanced the sensing properties. Therefore, the H2S sensors based on the Ag-In2O3 nanorod composites showed significantly improved sensing performance than those based on the pure In2O3 nanorods. The optimized content of Ag nanoparticles is 13.6 wt%. Operated at room temperature, the H2S sensors made of 13.6 wt% Ag-In2O3 nanorod composites exhibited an ultra-high response of 93719 to 20 ppm H2S and a superior detection limit of 0.005 ppm. The sensor also showed good reversibility, good selectivity, excellent reproducibility and stability for detection of H2S gas. [ABSTRACT FROM AUTHOR]

Deformation mechanisms of as-deposited and post-annealed Ti50.2Ni49.6, Ti50.3Ni46.2Cu3.5 and Ti48.5Ni40.8Cu7.5 thin films were investigated using the in situ synchrotron X-ray diffraction technique. Results showed that initial crystalline phases determined the deformation mechanisms of all the films during tensile loading. For the films dominated by monoclinic martensites (B19′), tensile stress induced the detwinning of 〈011〉 type-II twins and resulted in the preferred orientations of (002)B19′ parallel to the loading direction (∥ LD) and (020)B19′ perpendicular to the LD (⊥ LD). For the films dominated by austenite (B2), the austenite directly transformed into martensitic variants (B19′) with preferred orientations of (002)B19′ ∥ LD and (020)B19′ ⊥ LD. For the Ti50.3Ni46.2Cu3.5 and Ti48.1Ni40.8Cu7.5 films, martensitic transformation temperatures decreased apparently after post-annealing because of the large thermal stress generated in the films due to the large differences in thermal expansion coefficients between the film and substrate. [ABSTRACT FROM AUTHOR]

Hierarchical structured tungsten oxide nanocrystals were synthesized via the hydrothermal route assisted by a capping agent of ammonium benzoate (AB). The products were characterized using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. The experimental results show that the crystal microstructures could be changed from flower-shape to star-shape by changing the mole ratio of ammonium benzoate to sodium tungstate (AB/ST). The crystal phases were changed from orthorhombic WO⋅0.33HO to hexagonal WO with the increase in the concentration of AB. Based on the results from Fourier transform infrared spectroscopy and time-dependent growth analysis, a self-assembly growth mechanism has been proposed for the formation of flower, spherical, and star-netted microstructures at different mole ratios of the AB/ST. The star-netted WO nanocrystals were applied as a sensitive layer for humidity sensing performed using a Love-mode ZnO/36 Y-cut LiTaO surface acoustic wave device, and a stable and sensitive response to the change of relative humidity was obtained. [ABSTRACT FROM AUTHOR]

Abstract: Love mode surface acoustic wave (SAW) ultraviolet (UV) sensors were fabricated through sputtering ZnO films on 36° Y-cut LiTaO3 substrate. Crystalline structure, morphology and photoluminescence (PL) of the sputtered ZnO films were characterized using X-ray diffraction, atomic force microscopy and fluorescence spectrometer. The PL spectra revealed that different defects in the ZnO films were dependent on the oxygen partial pressure during deposition. UV sensing measurements showed that at a power density of 350μWcm−2, the amplitude of the Love mode SAW UV sensor decreased up to −6.4dB with a frequency shift of ∼150kHz under a 254nm illumination. When this device was illuminated with 365nm UV light at 570μWcm−2, the amplitude of the transmission signal decreased only −2.5dB without any significant frequency shift. A frequency hopping effect during the downshift and recovery periods was identified due to the simultaneous interplays between the variations of the acoustic velocity and attenuation during the acoustic-electric interaction. [Copyright &y& Elsevier]

Thickness dependency and interfacial structure effects on thermal properties of AlN thin films were systematically investigated by characterizing cross-plane and in-plane thermal conductivities, crystal structures, chemical compositions, surface morphologies and interfacial structures using an extended differential 3ω method, X-ray diffraction (XRD) analysis, X-ray photoelectron spectroscopy, atomic force microscopy (AFM) and transmission electron microscopy. AlN thin films with various thicknesses from 100 to 1000 nm were deposited on p-type doped silicon substrates using a radio frequency reactive magnetron sputtering process. Results revealed that both the cross- and in-plane thermal conductivities of the AlN thin films were significantly smaller than those of the AlN in a bulk form. The thermal conductivities of the AlN thin films were strongly dependent on the film thickness, in both the cross- and in-plane directions. Both the XRD and AFM results indicated that the grain size significantly affected the thermal conductivity of the films due to the scattering effects from the grain boundary. [ABSTRACT FROM AUTHOR]

In this paper, a one-step thermal evaporation approach was used for fabrication of indium bismuth sulphide thin films, and the synergetic effects of co-evaporation of two sources (indium granules and Bi 2 S 3 powders) were investigated using different characterization techniques. X-ray diffraction (XRD) analysis confirmed the crystalline orthorhombic structure for the post-annealed samples. Surface roughness and crystal size of the obtained film samples were increased with increasing annealing temperatures. Analysis using X-ray photoelectron spectroscopy showed the formation of the InBiS 3 structure for the obtained films, which is also confirmed by the XRD results. The optical absorption coefficient value of the annealed samples was found to be in the order of 10 5  cm −1 in the visible region of the solar spectrum. The optical band gap energy and electrical resistivity of the fabricated samples were observed to decrease (from 2.2 to 1.3 eV, and from 0.3 to 0.01 Ω–cm , respectively) with increasing annealing temperatures (from 200 to 350 °C), indicating the suitability of the prepared InBiS 3 thin films for solar cell applications. [ABSTRACT FROM AUTHOR]

Abstract: A new one-step method utilizing a special holder for a direct current magnetron sputtering system has enabled simultaneous deposition of ZnO films with different substrate tilt angles on quartz and silicon substrates. Observation from scanning electron microscopy shows that a typical columnar structure is obtained and the column inclination angle varies from 0° to 34°. From X-ray diffraction analysis, the strains in the ZnO films decrease with increasing substrate tilt angle, which is confirmed by the variation of the longitude optical phonon vibration in the Raman spectra. The band-gap energies decrease from 3.19eV to 3.07eV mainly due to the changes of strain relaxation induced by the defect variations in the films. Photoluminescence spectra revealed that the generation, type and concentration of the complex defects are influenced by the substrate tilt angle. [Copyright &y& Elsevier]

The title nanowires are hydrothermally synthesized from aqueous mixtures of Ce(NO3)3, urea, and NaOH (autoclave, 100 °C, 24 h). [ABSTRACT FROM AUTHOR]