Advanced Materials Research Vol. 787

Abstract: Chemical bath deposited nickel oxide (NiO) thin film samples were grown at room temperature of 30 °C on glass substrates. Samples k₁, k₂, and k₃ were annealed for one hour at temperatures of 100 °C, 200 °C and 300 °C respectively, while as grown sample k₄ served as a reference. A second set of samples k₅, k₇, and k₈ were annealed at a constant temperature of 300 °C for time durations of 1H, 2H and 3H respectively, with as grown sample k₆ as a reference. The spectral absorbance, transmittance and reflectance of all the thermally treated thin film samples were measured with a spectrophotmeter (D model Avantes Spec 2048 version 7.0) in the UV-VIS-NIR region of 300-900 nm wavelength. The results show distinctive variations in all the spectral properties for different combinations of annealing time and temperature, each starting at a threshold wavelength of 300 nm and ending with a distinctive minimum or maximum value. Deduced graphical values of the refractive index also show distinctive variations. For annealing time of 3 hours at a temperature of 300 °C, the results produced symmetric reflectance and symmetric refractive index with maximum values of 8% and 0.293 occurring at 500 nm wavelength and photon energy of 2.5 eV respectively. Direct transition band gap energy obtained for all the samples lie between 3.68-3.84 eV. The results reported in this paper clearly indicate that optimum combinations of production parameters of nickel oxide thin films can yield specific values of the properties for specific applications.

Abstract: Orthorhombic c-axis-oriented TbMnO₃ films of 24~ 200 nm thickness were grown epitaxially on SrTiO₃ (001) single crystal substrates by using pulsed laser deposition technique. The temperature (2~300 K) dependence of magnetization data were obtained on a quantum design superconducting quantum interference device. When the magnetic field was applied in the a-b plane, the magnetization evidently displayed an anomalous antiferromagnetic ordering around 156 K, which was related to the film thickness seriously. A broad transition peak at the same temperature was also observed when the applied field was along the c axis direction. The anomalies at high temperature were not observed in bulk TbMnO₃ materials. These results were discussed in terms of unexpected magnetic ordering of the Mn³⁺ moments inducde by the interface strain between the films and the substrates.

Abstract: Stimulation of sandstone formations is a challenging task, which involves several chemicals and physical interactions of the acid with the formation. Some of these reactions may result in formation damage. Matrix acidizing may also be used to increase formation permeability in undamaged wells. Mud acid has been successfully used to stimulate sandstone reservoirs for a number of years. It is a mixture of hydrofluoric (HF) and hydrochloric (HCl) acids designed to dissolve clays and siliceous fines accumulated in the near-wellbore region. For any acidizing process, the selection of acid (Formulation and Concentration) and the design (Pre-flush, Main Acid, After-flush) is very important. Different researchers are using different combinations of acids with different concentrations to get the best results for acidization. Mainly the common practice is combination of Hydrochloric Acid and Hydrofluoric Acid with Concentration (3% HF 12% HCl). This paper presents the results of a laboratory investigation of orthophosphoric acid instead of hydrochloric acid in one combination and the second combination is fluoboric and formic acid and the third one is formic and hydrofluoric acid on undamaged low permeable sandstone formation. The results are compared with the mud acid and the results analyzed are permeability, color change and FESEM Analysis. All of these new combinations show that these have the potential to be used as acidizing acids in sandstone formations.

Abstract: The compound-anion polycrystalline material Yb³⁺:Na₅Bi (WO₄)₂(MoO₄)₂ was synthesized by flux method. Many characterization of XRD, DSC-TG, absorption spectrum and emission spectrum were studied. The result is shown that the new crystal belongs to Tetragonal, and space group is I4₁/a (88). Its melting point is 619 °C and the absorption band, emission band, center emission wavelength are about 83 nm, 50 nm, 1006 nm respectively.

Abstract: Currently, thermal energy generation through coal combustion produces ash particles which cause serious environmental problems and which are known as Fly Ash (FA). FA main components are oxides of silicon, aluminum, iron, calcium and magnesium in addition, toxic metals such as arsenic and cobalt. The use of fly ash as a cement replacement material increases long term strength and durability of concrete. In this work, samples were prepared by replacing cement by ground fly ash in 10, 20 and 30% by weight. The characterization of raw materials and microstructure was obtained by Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD). The final results showed that the grinding process significantly improves the mechanical properties of all samples when compared replacing a mortar made with cement by ground fly ash and the reference samples without added fly ash. The beneficial effect of the ground fly ash can increase the use of this product in precast concrete industry.

Abstract: ZnS is well known for its potential uses, both in crystal form and powder, as optoelectronic devices and as a phosphor. In this work, we prepared ZnS-intercalated montmorillonite by the in situ solid-solid reaction between Zn (II)-montmorillonite and sodium sulfide. A potentiometric electrode was constructed from a mixture of ZnS-intercalated montmorillonite, artificial graphite, polytetrafluoroethylene (PTFE) and carboxymethylcellulose (CMC) in an appropriate ratio. The electrode was used to determine S^2- in aqueous solution, graphs of log [S^2-] vs. measured voltage gave linear relation up to 3^rd order of ion concentrations. It can be said that, this is the first time that ZnS-intercalated montmorillonite is used to construct a potentiometric electrode. Apart from a good precision, the electrode is good for its selectivity, durability and low cost.

Abstract: In order to further improve the deposition process of the W-doped DLC films synthesized by a hybrid deposition method of vacuum cathodic arc, ion beam deposition, and magnetron sputtering, the paper studied the effect of vacuum cathodic arc etching prior to the deposition on the surface morphology, chemical bond status, hardness, elastic modulus, adhesion, friction, and wear of the films. It was found that the surface defects in the W-doped DLC films, which increase the average value and fluctuation of the friction coefficient of the W-doped DLC films, are mainly produced by vacuum cathodic arc etching. The adhesion and wear resistance of the W-doped DLC films can be obviously improved by arc etching while arc etching has an unobvious effect on the chemical bonding status, hardness, and elastic modulus of the W-doped DLC films.

Abstract: The thermal decomposition of organic peroxides are widely used as coagulant for organic compounds, however, its thermal hazardous characteristics have already caused serious accidents in chemical industries, which limited its application in much more strict conditions. Organic peroxides of C18H10O11 and C18H18O7 are two new candidates fitted for industrial explosive. However, as we best known there is little reports available on the geometry structure in the past decades. In this work, by means of quantum chemistry calculation, the relation of safety with molecular structure of C18H10O11 and C18H18O7 are discussed. The molecules with more activity O and the activity part more dispersedly exhibit higher stable, and the configuration has good safety. All the energy of molecule b is higher than that of molecule a. The stability of different configurations are 6a>7a>8a>9a>5a>1a>4a>3a=2a and 1b>7b>5b>6b>4b>2b>3b>8b, respectively, suggesting the structures of 6a,3a,2a,1b,8b exhibit high safety.

Abstract: The equibiaxial extensional viscosity of the doughs prepared from gluten and xanthan gum at three levels was determined in this work. The gluten-xanthan gum mixture exhibited strain rate thinning behavior at constant strain, and can be described by power-law model. The consistency index increased with increasing strain and xanthan gum content, while flow behavior index decreased with increasing strain and increased with increasing xanthan gum content. Cross-links in gluten network increased after xanthan gum addition and the increase magnitude was more markable at higher deformation rate.

Abstract: In this paper, addition of Fe-Ni, MnZn-ferrite, and CNF (carbon nanofiber) absorbers in the Kevlar fiber fabric-reinforced epoxy resin composites resulted in excellent absorbing properties as well as other required properties such as light-weight (as low as 2.2 g/cm³), small thickness (~2 mm), high mechanical strength (up to 380 MPa) and thermal stability (up to 120 °C). Reflection loss testing of the laminates FM-3 showed that the peak reflection loss was-45 dB at the frequency of 10.4 GHz, and the absorbing waveband at-10dB was 12 GHz (from 6 to 18GHz). The study also indicated that the content of the added absorbers was limited by the viscosity (or flowability) of the resin-absorber mixed suspensions.