Synthesis of NiO nanowalls by thermal treatment of Ni film deposited onto a stainless steel substrate

Two-dimensional nanostructures have a variety of applications due to their large surface areas. In this study, the authors present a simple and convenient method to realize two-dimensional NiO nanowalls by thermal treatment of a Ni thin film deposited by sputtering onto a stainless steel substrate. The substrate surface area is supposed to be significantly increased by creating nanowalls. The effects on the nanowall morphology of the thermal treatment temperature and duration are investigated. A mechanism based on the surface diffusion of Ni2+ ions from the Ni base film is then proposed for the growth of the NiO nanowalls. The as-synthesized NiO nanowalls are characterized by scanning electron microscopy, energy-dispersive x-ray analysis, x-ray diffraction, transmission electron microscopy and high resolution transmission electron microscopy

A new intersecting tunnel structure in the AIMIII[PO3(OH)]2 series for AI = Ag, MIII = In : Analysis of structural relationships.

A new indium hydroxyphosphate containing silver, AgIn[PO3(OH)]2, has been synthesized using hydrothermal method. It crystallizes in the P21/c space group with the cell parameters a = 6.6400(2)Å, b=14.6269(6)Å, c=6.6616(4)A, β=95.681(5)°, V=643.82(6)Å3, Z=4. Its three-dimensional framework, built up of comer-sharing PO3(OH) tetrahedra and InO6 octahedra, presents intersecting tunnels running along and [100] directions, in which the Ag+ cations are located. The presence of hydroxyl groups has been confirmed from IR spectroscopy studies and hydrogen atoms were located from the single crystal X-ray diffraction study. The structural relationships with the other compounds of general formula AΙΜΙΙΙ[PΟ3(OH)]2 are analyz

Magnetic properties of cobalt and manganese oxide spinel ceramics

Magnetic susceptibility measurements, magnetization and neutron diffraction results at low temperature for cobalt and manganese oxide spinel ceramics are presented. The Curie temperature varies similarly with the sample composition in ceramics and powders. The experimental molar Curie constant variation is explained by the presence of Co2+, CoIII, Mn3+ and Mn4+, and possibly Co3+ in the octahedral sites for the cobalt rich phases. The magnetic moments of the cations in tetrahedral and octahedral sites are not collinear and the global magnetization is oriented in a third direction

Microstructure of Ba1−xLaxTiO3−δ ceramics sintered by spark plasma sintering

Nano-sized Ba1−xLaxTiO3 (0.00 ≤ x ≤ 0.14) powders were prepared by a coprecipitation method and calcined at 850 °C in air. The corresponding ceramics were obtained by Spark Plasma Sintering (SPS) at 1050 °C. These ceramics are oxygen deficient and are marked as Ba1−xLaxTiO3−δ. Both powders and ceramics were characterized by X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The effect of lanthanum concentration on the densification behavior, on the structure and the microstructure of the oxides was investigated. Average grain sizes are comprised between 54 (3) nm and 27 (2) nm for powders, and 330 (11) nm and 36 (1) nm for ceramics according to the La-doping level. Powders crystallize in the cubic (or pseudo-cubic) perovskite phase. The structure of ceramics consists in a mixture of cubic (or pseudo-cubic) and tetragonal perovskite type phases. As the lanthanum content increases, the tetragonality of the samples decreases, as well as the grain size

Realization of aligned three-dimensional single-crystal chromium nanostructures by thermal evaporation

Aligned three-dimensional single-crystal chromium nanostructures are fabricated onto a silicon substrate by thermal evaporation in a conventional thermal evaporator, where the incident angle of Cr vapor flux with respect to the substrate surface normal is fixed at 88°. The effects of the deposition time and incident angle on the morphology of the resulting nanostructures are investigated. The achieved Cr nanostructures are characterized by scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, and surface area measurement. This study provides a convenient way to fabricate three-dimensional single-crystal Cr nanostructures, which is suitable for batch fabrication and mass production. Finally, the same technique is employed to fabricate the nanostructures of other metals such as Ag, Au, Pd, and Ni

Electrical conductivity of parylene F at high temperature

The electrical conductivity of both as-deposited and annealed poly(α,α,α′,α′-tetrafluoro-p-xylylene) (PA-F) films has been investigated up to 400°C. The static conductivity (σ DC) values of PA-F measured between 200°C and 340°C appear to be ∼2.5 orders of magnitude lower for annealed films than for as-deposited ones. This change is attributed to a strong increase in the crystallinity of the material occurring above 340°C. After annealing at 400°C in N2, the σ DC value measured at 300°C, for instance, decreased from 3.8 × 10−12 Ω−1 cm−1 to 7.5 × 10−15 Ω−1 cm−1. Physical interpretations of such an improvement are offered

‘Soft’ phonon modes,structured diffuse scattering and the crystal chemistry of Fe-bearing sphalerites

Electron diffraction has been used to carefully investigate the reciprocal lattices of a range of iron-bearing sphalerites looking for evidence of Fe clustering and/or Fe/Zn ordering in the form of either additional satellite reflections or a structured diffuse intensity distribution accompanying the strong Bragg reflections of the underlying sphalerite-type average structure. While a highly structured diffuse intensity distribution in the form of transverse polarized f110g sheets of diffuse intensity has been detected and found to be characteristic of all compositions,it does not appear to arise from Fe clustering and/or Fe/Zn ordering. Rather inherently low frequency,and therefore strongly thermally excited,phonon modes propagating along reciprocal space directions perpendicular to each of the six /110S real space directions of the average structure are suggested to be responsible for these f110g sheets of diffuse intensity. Monte Carlo simulation (for a range of Zn–S,Zn–Zn and S–S interaction strengths) and subsequent Fourier transformation is used to confirm the existence of these low-frequency phonon modes of distortion as well as to show that they are an intrinsic,predictable property of the corner-connected tetrahedral structure of sphalerite. The low-frequency phonon modes involve coupled (Zn,Fe) and S motion in one-dimensional strings along /110S real space directions

Synthesis process of nanowired Al/CuO thermite.

Al/CuO nanothermites were fabricated by thermal oxidation of copper layer at 4501C for 5 hand by aluminum thermal evaporation: thermal evaporation allows producing thin layer less than 2 mminsize. The copper has been deposited by electroplating or thermal evaporation depending on the required thickness. The obtained diameter of Al/CuO nanowiresis 150–250nm. Al/CuO nanowires composite were characterized by scanning electronmicroscopy (SEM), X-raydiffraction (XRD), differential scanning calorimetry (DSC) and differential thermal analysis (DTA). Two distinct exothermicreactions occurred at 515 and 6671C and total energy release of this thermite is 10kJ/cm

A flow-through hydrothermal cell for in situ neutron diffraction studies of phase transformations

A flow-through hydrothermal cell for the in situ neutron diffraction study of crystallisation and phase transitions has been developed. It can be used for kinetic studies on materials that exhibit structural transformations under hydrothermal conditions. It is specifically designed for use on the medium-resolution powder diffractometer (MRPD) at ANSTO, Lucas Heights, Sydney. But it is planned to adapt the design for the Polaris beamline at ISIS and the new high-intensity powder diffractometer (Wombat) at the new Australian reactor Opal. The cell will operate in a flow-through mode over the temperature range from 25–300 1C and up to pressures of 100 bar. The first results of a successful transformation of pentlandite (Fe,Ni)9S8 to violarite (Fe,Ni)3S4 under mild conditions (pH4) at 120 1C and 3 bar using in situ neutron diffraction measurements are presented

Synthesis of large-area and aligned copper oxide nanowires from copper thin film on silicon substrate

Large-area and aligned copper oxide nanowires have been synthesized by thermal annealing of copper thin films deposited onto silicon substrate. The effects of the film deposition method, annealing temperature, film thickness, annealing gas, and patterning by photolithography are systematically investigated. Long and aligned nanowires can only be formed within a narrow temperature range from 400 to 500°C. Electroplated copper film is favourable for the nanowire growth, compared to that deposited by thermal evaporation. Annealing copper thin film in static air produces large-area, uniform, but not well vertically aligned nanowires along the thin film surface. Annealing copper thin film under a N2/O2 gas flow generates vertically aligned, but not very uniform nanowires on large areas. Patterning copper thin film by photolithography helps to synthesize large-area, uniform, and vertically aligned nanowires along the film surface. The copper thin film is converted into bicrystal CuO nanowires, Cu2O film, and also perhaps some CuO film after the thermal treatment in static air. Only CuO in the form of bicrystal nanowires and thin film is observed after the copper thin film is annealed under a N2/O2 gas flow