Advanced Materials Research Vols. 148-149

Abstract: The (Ba0.88Ca0.12)( Zr0.12Ti0.88)O3 powders and piezoelectric ceramics were prepared by sol-gel process. The reaction process was analyzed with the help of thermo gravimetric and differential scanning calorimetry. X-ray diffraction characterized results showed that the structure of the (Ba0.88Ca0.12)( Zr0.12Ti0.88)O3 powders was perovskite structure and the particle size was approximately 37nm. Piezoelectric measurements revealed that Curie temperature and the maximum piezoelectric coefficient d33 is 95°C and 215pm/V, respectively.

Abstract: In this paper, we prepared BaAl2O4 and Co:BaAl2O4 nanoparticles from aqueous solution of metal nitrates containing citric acid as a chelating agent by sol-gel method. The gel was heat-treated at temperatures ranging from 710°C to 1000°C. The heat-treated powders were characterized by X-ray diffraction analysis (XRD), infrared spectra (IR) and luminescence spectroscopy. From the results of the characterization, we find the prepared powders are pure nano-particles of BaAl2O4 after heat-treated at 900°C temperature. The emission spectra of Co: BaAl2O4 in the visible region indicates the existence of Co2+ in the tetrahedral sites of BaAl2O4 nano-crystal.

Abstract: Wall thickness is measured by a micrometer on shells after piercing, hollows after rolling and tubes after stretch reducing in an Assel production line for seamless steel tubes. The characteristics of wall thickness eccentricity are exhibited, and the heredity and origin of wall thickness eccentricity are analyzed. Finally, the factors influencing wall thickness eccentricity are discussed. The results show that: (1) Wall thickness eccentricity originates from temperature eccentricity in cross section of round billets, comes into being on shells in piercing process, and is passed down to hollows and finally to tubes; (2) Bigger feed angle of piercing, smaller plug diameter and less stability of plug bar will increase wall thickness eccentricity, while complying to the influence of temperature eccentricity on round billets.

Abstract: Multiscale design dealing with 2-scale material and product system is implemented by employing probabilistic analytical target cascading (PATC) and weighted stochastic response surface method (WSRSM) in this paper. PATC allows design autonomy at each scale subsystem by formulating the multiscale design system as a multilevel structure. WSRSM ensures uncertainties to be propagated within and across each scale accurately and efficiently. Comparative study on a multiscale bracket design problem shows that the results obtained by our strategy are very close to the reference values. It is demonstrated that PATC and WSRSM are highly effective and applicable on multiscale design.

Abstract: The nanometer titanium dioxide (TiO2) was prepared by reverse titration method with titanium trichloride and titanium tetrachloride at low temperature. The prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and laser diffraction particle size analyzer, the photocatalytic activity of the samples was also evaluated. The results showed that the prepared TiO2 was nanometer anatase titania with an average particle size of 56.39 nm and the zeta potential of +39.42 mV. The nanometer anatase titania had the best photocatalytic activity than the TiO2 prepared by reverse titration or forward titration with titanium tetrachloride and a good stability.

Abstract: Cu-loaded TiO2 nanotube arrays were fabricated by immersing the anodized nanotube arrays in Cu(NO3)2 solution and then post-annealed. Copper oxide with diameter about 20 nm was loaded on the nanotube arrays with tube diameter about 140 nm, the wall thickness about 40 nm and the length about 4 µm. Cu-loaded TiO2 nanotube arrays showed remarkable improvement of photochemical activity. The photocurrent of Cu-loaded sample soaked in 0.02 M Cu(NO3)2 solution was about 2.5 times higher than that of unloaded sample.

Abstract: Zn-Al hydrotalcite exhibited fluorescence property without fluorescent substances intercalation. Its maximum excitation wavelength was 406nm and maximum emission wavelength was 523nm. In this study citric acid and adipic acid were introduced into the interlayer of LDH, which enlarged the interlayer spacing. It was found that the fluorescence property was influenced by anions in the interlayer of hydrotalcites. And it would be favorable to bind with other organic compounds to get photocatalysis materials for citric acid modified Zn-Al hydrotalcite. Meanwhile, the fluorescence intensity was enhanced greatly after modified by adipic acid, so it could be used as photocatalyst precursors.

Abstract: Barium zirconate titanate Ba(Ti1-yZry)O3 (BZT, y = 0.02, 0.07, 0.09, 0.12, 0.15) ceramics have been prepared by sol–gel process. All the BZTx ceramics exhibited perovskite phase detected by X-ray diffraction, and the diffraction peaks shift to lower angle with increasing the content of Zr. Dielectric susceptibilities are up to 15500, and tunability up to 74.9% under electric field 6.8 kV/cm at 100 Hz.

Abstract: Novel base catalysts were obtained by subjecting Y zeolites to nitridation. These materials were characterized by elemental analysis, X-ray diffraction, BET surface area analysis, In situ diffuse reflectance infrared fourier transform Spectroscopy (in situ DRIFTS), Pyrrole adsorption. The results indicated nitrogen-incorporated NaY zeolite was well ordered and possess high surface area and pore volume. In situ DRIFTS experiments confirmed that N atoms had been introduced into the framework by nitridation to form -NH2- or -NH- species. It was found that Lewis basicity of these oxynitride materials increased by the pyrrole adsorption. Furthmore, the basic catalytic properties of nitrogen-incorporated zeolites were evaluated by Knoevenagal condensation of benzaldehyde with diethyl malonate and enhanced yield of product was achieved.

Abstract: The magnetically mesoporous SiO2@Fe3O4 nanocomposites were synthesized by sol-gel method and extracted by ethanol solution. The support was characterized by high resolution transmission electron microscopy (HRTEM), N2 adsorption-desorption isotherms and vibration sample magnetometer (VSM). A long carbon chain Oxime Carbapalladacycle complex was grafted onto this support and the effect of the catalyst was investigated for the Heck reaction of aryl halides with olefins. The results demonstrated that the support with diameter 150 nm was superparamagnetic characteristics (saturation magnetization was 8.78 emu/g) and the thus recycled catalyst could be reused for 6 times with significant loss of activity in the coupling-reaction of iodobenzene and ethyl acrylate. In addition, the catalyst could be simply recycled with the assistance of an external magnet.