TiO_(2)/CuO Films Obtained by Citrate Precursor Method for Photocatalytic Application

In the present work, the hybrid catalyst films of TiO2/CuO containing up to 10% in mol of copper were deposited onto glass surface. Precursor solutions were obtained by citrate precursor method. Films were porous and the average particle size was 20 nm determined by FEG-SEM analysis. The photocatalytic activities of these films were studied using Rhodamine B as a target compound in a fixed bed reactor developed in our laboratory and UV lamp. It was observed that the addition of copper to TiO2 increased significantly its photocatalytic activity during the oxidation of Rhodamine B. The degradation exceeded 90% within 48 hours of irradiation compared to 38% when pure TiO2 was used. Moreover, there was a reduction in the particles band gap energy when compared to that of pure TiO2. These results indicate that the TiO2/CuO films are promising catalysts for the development of fixed bed reactors to be used to treat effluents containing azo dyes.

Morphology controllable synthesis of yttrium oxide-based phosphors from yttrium citrate precursors

A novel yttrium citrate-templated conversion method for morphology controlled synthesis of Y2O3 microspheres, microflowers and microsheets was reported for the first time. The precursors with controllable morphologies were synthesized with a homogenous precipitation method in aqueous solution without any surfactant. Y2O3 samples with well-preserved morphological architectures were obtained by a subse-quent thermal transformation strategy. The chemical formula of the precursor was identified and a two-stage growth mechanism was proposed. The effects of the aging time, reaction temperature, reactant concentration and molar ratio of yttrium nitrate to sodium citrate were discussed. The photoluminescence properties of the Y2O3：Eu3＋ microspheres, microflowers and microsheets prepared were also studied.

Synthesis, Electrical and Magnetic Properties of Fe304 Doped by Dy^3＋

The Dy^3＋ -doped Fe3O4 samples were synthesized by sol-gel method, and the effects of dopant on the electrical and magnetic properties were investigated. According to XRD analysis, the high concentration doping of dysprosium ions in Fe3O4 can not be obtained due to the difference of ionic radius, and Fe^3 ＋ ions are replaced by only a small amount of dysprosium ions. The magnetic property was characterized by VSM. The substitution results in the change of saturation magnetization, which may be due to the complex effects of increasing magnetization resulted from Dy^3＋ substitution and decreasing magnetization resulted from the impurity. The electrical property was characterized by four-probe method. With the increasing eoped content, magnetoresistance also increases, then decreases, and increases again. The spin-polarization of doped samples is lower than that of Fe3O4. Lower spin-polarization results in lower tunneling magnetoresistance. Fortunately, barrier was obtained by the second phase at the same time when sample was synthesized. The increase of appropriate barrier height leads to the change of tunneling magnetoresistance.

Comparison of rare earths doping(neodymium and samarium) on structural and magnetic properties of Ni-Zn-Bi nanoferrites

Excellent magnetic properties in ferrites are required for high-frequency applications and for wastewater treatment. Thus, the present study shows the comparison of magnetic and structural properties of Nd and Sm substituted Ni-Zn-Bi ferrites with the series Ni_(0.5)Zn_(0.5)Bi_(0.04)Nd_(x)Fe_(1.96-x)O_4(with step size 0.002)and Ni_(0.5)Zn_(0.5)Bi_(0.04)Sm_(x)Fe_(1.96-x)O_4(with step size 0.02) prepared using citrate precursor method. The impact of the substitution of rare earth ions(Nd and Sm) on magnetic properties of the synthesized samples is observed using a vibrating sample magnetometer(VSM). The saturation magnetization values enhance considerably from 52 to 58 emu/g for Nd^(3+)ions and 39 to 57 emu/g for Sm^(3+) ions, thus, making these materials magnetically hard. Further, the higher value of coercivity is also observed ranging from133 to 167 Oe for Nd^(3+)ions and 81 to 155 Oe for Sm^(3+) ions. The shape of hysteresis loops indicates a super paramagnetic and ferromagnetic behavior in the obtained samples. The squareness ratio value is<0.5, suggesting the uniaxial anisotropy of particles and hence, these ferrites are suitable for microwaveabsorbing and in permanent magnetic materials. The X-ray diffraction(XRD) pattern shows the formation of pure cubic crystallites, where, lattice parameters range from 0.840 to 0.839 nm and from 0.838to 0.839 nm for Nd^(3+)and Sm^(3+) ions substitution, respectively. The crystallite size ranges between 28.63to 29.89 nm and 18.33 to 26.23 nm, for substitution of Nd^(3+)and Sm^(3+) ions, respectively. Field emission scanning electron microscopy(FESEM) shows the formation of homogeneous grains, whereas, energy dispersive spectrometer(EDS) counts describe the purity of the samples. The Sm concentration x = 0.10has the maximum surface area with value of 42.6 m^(2)/g which proves to be having good data storage application due to high surface area. The zero-field cooled(ZFC) and field cooled(FC) data show that Nddoped Ni-Zn-Bi nanoferrites show superparamagnetic behaviour in the room temperature range which makes them suitable for practical applications.