Advanced Materials Research Vol. 702

Abstract: Pb(Zr_0.52Ti_0.48)O₃/La_0.8Ca_0.2MnO₃ (PZT/LCMO) thin films were deposited onto SrTiO₃ (STO) single crystalline substrates by pulse laser deposition (PLD). The AFM morphology results show that the LCMO ( PZT) layer is very smooth and homogenous with very low values of RMS roughness. The XRD results show that only the (00l) peaks are observed for both LCMO and PZT layers which are single crystalline and have an epitaxial relationship with STO substrates: PZT (001)//LCMO(001)//STO (001). The FWHM values of the (001) omega-rocking curves of the LCMO and PZT film were 0.276o and 0.565o, respectively, which suggests high crystalline quality of epitaxial PZT/LSMO LSMO heterostructures were grown on STO substrates.

Abstract: In paper problem concerning inoculation of primary structure of aluminum with purity of 99,5% and 99,8%, which is realized mainly by intensification of liquid metal movement in mould is presented. In aim of realization of forced movement during the crystallization of liquid metal was used rotating electromagnetic field produced by the induction coil supplied by current with elevated frequency. The degree of structure refinement was represented by equiaxed crystals zone content on transverse section of ingot and average area of macro-grain in this zone. Effect of structure refinement obtained by influence of electromagnetic field was compared with refinement obtained by use of traditional inoculation, which consists in introducing of additives i.e. titanium, boron and carbon to metal bath. The results of studies and their analysis show possibility of effective refinement of pure Al primary structure, only with use of rotating electromagnetic field and without necessity of application of inoculants such a Ti, B and C. This method of inoculation is important, because inoculants decrease the degree of purity and electrical conductivity of pure Al. Moreover Ti and B are reason of point cracks formation during rolling of ingots.

Abstract: Antimony doped tin oxide (ATO) conductive nano-particles are synthesised by alkoxide hydrolysis method using SnCl4•5H2O and SbCl3 as raw materials. The optimum parameters are determined as: Sb3+ doped molar concentration 15%, reaction temperature 60°C and roasting temperature 600°C. Under optimum conditions, the synthesised nano-particles are characterized by means of X-ray diffraction (XRD) and transmission electron microscope (TEM). XRD results show that all Sb ions came into the SnO2 lattice to substitute Sn ions. The image of TEM shows the ATO conductive nano-particles average size is 5 nm. Volume resistivity lowest value of ATO nano-particles is 141 Ω•cm.

Abstract: BiVO₄ composited with TiO₂ (BVO-T) nanoparticles was sensitized by tetrakis(4-carboxy phenyl)porphyrin (TCPP) dye (BVO-T/P) to efficiently utilize visible light in the photodegradation reaction. To investigate the photoactivity of this catalyst, its photocatalytic efficiency was compared to the pure TiO₂, pure BiVO₄, and BiVO₄ composited with TiO₂ in the destruction of methyl orange in the visible light. Furthermore, the kinetic of the MO degradation as well as the stability of BVO-T/P photocatalyst was investigated.

Abstract: Ni-diamond composite coatings are conducted by electrodepositon. The crystal structure and surface morphology of the composite coatings were examined with X-ray diffraction (XRD) and scanning electron microscopy (SEM) and the mechanism of Ni-diamond co-deposition is conducted by catholic polarization and cyclic voltammetry method. The result reveals that diamond particles are successfully embed in Ni matrix and the coatings have an amorphous structure. Cyclic voltammetry indicate that nickel deposition process is an irreversible electrode reaction and cathode polarization curve shift towards positive with the increase of scan rates. Cathodic polarization curve shows that reduction potential of nickel to shift to more negatives with the addition of complexing agent and the slope of the polarization curve is decrease; The addition of brightener and dispersant hinder the deposition of Ni2+ and promote the growth of crystal nucleus; The join of wetting agents and diamond particles have no big influence on the deposition of nickel.

Abstract: In this paper, structural and electrochemical characteristics of the Cr-Al₂O₃ nano composite coatings were investigated. Cr-Al₂O₃ nano composite coatings were electrodeposited in electrolyte containing nano Al₂O₃ particles. The influences of nano Al₂O₃ particles on the chemical composition, morphological and structural characteristics of the electrodeposited Cr-Al₂O₃ nano composite coatings were investigated using energy dispersive X-ray spectroscopy, scanning electron microscopy and X-ray diffractometry. The electrodeposition behavior of Cr³⁺ ion and the action mechanism of electrolyte components such as auxiliary complexing agent, wetting agent, nano Al2O3 in the process of Cr-Al₂O₃ composite electrodeposition were investigated using the electrochemical measurement methods such as cyclic voltammetry and cathodic polarization. The results reveal that the nano Al₂O₃ particles can be codeposited in the Cr matrix, micro crystal structure of the Cr-Al₂O₃ nano composite coatings are obviously refined, Cr-Al₂O₃ nano composite coatings are amorphous structure.

Abstract: To obtain the approximately analytical solution of double-walled carbon nanotubes (DWNTs) nonlinear vibration. In this study, homotopy perturbation method (HPM) was used to solve nonlinear vibration equation of DWNTs. Novel and accurate analytical solutions for the frequency and displacement are derived. Comparison of the result obtained by the HPM with exact solutions reveals that only the first or second order approximation of the HPM leads to higher accurate solution.

Abstract: The amorphous/nanocrystalline Ni-Mo alloys are obtained in alkaline nickel carbonate solution in this paper. By using X-ray diffraction (XRD) and scanning electronic microscopy (SEM) to testify microstructure and morphology of the deposits. It is found that the deposits are composed of amorphous and nanocrystalline structure phases. Compared with the nickel sulfate solution, the amorphous/nanocrystalline alloys are more accessible to be obtained in carbonate solution under the same conditions as the sulfate solution. The internal stress between the deposit and the basement is inexistent with the tiny granules and well-proportioned grains at the coating surface. The stability of the alkaline nickel carbonate solution is much better than the sulfate solution, and the deposit performance is relatively better and easy to be controlled.

Abstract: In this paper, in terms of stochastic equations theoretically analyzed the influence of the resonance dynamic intermolecular interaction on the formation of spectral vibrational bands of molecular crystals in the transition region to the rotation (plastic) phase. The mechanism that adequately describes the temperature behavior of Davydov splitting intramolecular vibrations value in the normal parrafins crystal phase was offered. This mechanism is associated with damping of vibrational excitons in their interaction with the lattice orientation defects arising from thermal excitation of the librational and rotational degrees of freedom of the molecules. It is shown that one of the factors that determine the appropriate rheological properties of bitumen is the existence in certain temperature ranges rotational phase of hydrocarbon components.

Abstract: Heat sink materials not only should have higher thermal conductivity, but also have smaller difference of thermal expansion with cooled material. diamond/copper composites were made by the powder metallurgy method. Vacuum slowly vapor deposition technique was employed to deposit a titanium film on diamond particles before mixing with Cu powder in order to improve the bonding strength between Cu and diamond particles during sintering. The thermal expansion of diamond/Cu d composite was measured in the temperature range from 50 to 600 °C. The results show that the titanium film on diamond improves the interfacial bonding and reduces the coefficient of thermal expansion (CTE) of Cu/diamond composites. The CTE of diamond/Cu composites decreases with increasing diamond volume fraction as the results of mixture rule and the intense restriction effect of diamond reinforcement on the copper matrix. The residual stresses and pores in the composites affect instantaneous thermal expansion of diamond/Cu composites.