Papers by Keyword: Titanate

Abstract: In this research, the effect of different hydrothermal treatment temperature (100, 150, and 200 °C) on the products obtained by hydrothermal method was studied. Various characterization techniques was carried out such as X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), energy dispersive of x-ray spectroscopy (EDX) and fourier transform infrared spectroscopy (FTIR). XRD analysis shows that titanate phase was formed at 150 and 200 °C hydrothermal treatment. On the other hand, at 100 °C anatase TiO₂ phase structured was gained which is similar with the TiO₂ precursor. Morphological study using FESEM revealed that nanofibers and nanorods samples obtained at 150 °C and 200 °C, respectively. At 100°C, irregular shaped particle was attained similar with TiO₂ precursors. FTIR spectra for the all studied sample displayed three main broad peaks at the range of 3700-2800, and 1800-1400 assigned to –OH stretching and deformation mode due to H₂O molecules and M-O stretching mode at 900-400 cm^-1 assigned to Ti-O bond.

Abstract: In this paper, the structural, magnetic and electrical properties of multiferroic BaFe₁₂O₁₉/MgFe₂O₄/BaTiO₃ composites have been studied. BaFe₁₂O₁₉/MgFe₂O₄/BaTiO₃ composites were synthesized by using the conventional solid state reaction technique and sintered at different temperatures. XRD analysis confirmed the existence of hexagonal BaFe₁₂O₁₉, cubic spinel MgFe₂O₄ and tetragonal BaTiO₃ for ferrites and ferroelectric phases, respectively. The suitable sintering temperature for preparing BaFe₁₂O₁₉/MgFe₂O₄/BaTiO₃ composites is between 1000 °C and 1050 °C. SEM analysis showed that as a whole the grain size increases and the pores is reduced with sintering temperature; thus the sample became denser. The coercive field and saturation magnetization decreases when sintering temperature is increased. Resistance of the samples decrease from 103 kW to 19 kW while the capacitance increases from 0.8 nF to 4.0 nF with sintering temperature.

Abstract: Solid solutions with defect perovskite structure have been obtained in the systems Li_0,5-уNa_yLa_0,5TiO₃, Li_0.5-yNa_yLa0.5◊Nb₂O₆ and Li_0.5-yNa_yLa0.5◊Та₂O₆ at 0 ≤ y ≤ 0.5. Their structure has been shown to undergo partial disordering with increasing sodium content in the system Li_0.5-yNa_yLa0.5◊Nb₂O₆ as in the system Li_0.5-yNa_yLa0.5◊Та₂O₆ structure has been ordering. Lithium diffusion in system Li_0,5-уNa_yLa_0,5TiO₃ follows a percolation model for the lithium diffusion. The ionic conductivity as a function of sodium content in the system Li_0.5-yNa_yLa0.5◊Nb₂O₆ has a maximum. The ionic conductivity of Li_0.5-yNa_yLa0.5◊Ta₂O₆ samples decreases with sodium content.

Abstract: Ni-doped titanate nanorods were synthesized from anatase TiO2 powder and Ni nitrate using a one-step hydrothermal reaction in alkaline solution. The nanorods are straight with lengths a few micrometer and diameters between 80 and 120 nm. The Ni-doped nanorods have the similar structure as hydrogen titanate nanorods of monoclinic structure. Magnetic measurement revealed that Ni-doped titanate nanorods are ferromagnetism at 300K. Electron paramagnetic resonance were studied and the spectra showed that a broad asymmetric signal and a signal in low field appeared due to the Ni ions incorporated into the titanate lattice. The results suggest that Ni-dopants play an important role in the ferromagnetism. The ferromagnetic response could be attributed to Ni intercalated into the titanate lattice.

Abstract: Titanate nanotubes were synthesized by a solvothermal process at a low temperature in a highly alkaline water-methanol mixed solution. Powders were characterized by XRD, TEM, BET and UV-vis absorption spectroscopy. The as-prepared samples was tested by the adsorptive process and photodegradation reaction of methylene blue (MB) dye under visible-light irradiation. The results indicated that the titanate samples are synthesized in the methanol-water volume ratios of 10:90, 20:80 and 30:70 are still highly absorbability and all the titanate samples as-prepared have higher photocatalytic activities compared with TiO₂ P25 in the degradation of MB under visible light irradiation.

Abstract: During rubber processing, many factors can affect the mechanical properties of rubber composite. The influence of ambient temperature and content of titanate coupling agent and modified attapulgite (OAT) on mechanical properties were investigated by preparing rubber composites and measuring. The results showed that the rubber composite which was filled 40phr OAT modified by 3% titanate and prepared at the ambient temperature above 20 had best tensile strength (18.93MPa). There is a special phenomenon that the tensile strength had a rapid increase from 4.72MPa to 18.93MPa, when the content of OAT changed from 20 to 40phr in the experiment.

Abstract: Spinel Li4Ti5O12 nanostructures were synthesized by hydrothermal treatment of hydrogen titanate at 150 oC and further calcinated at 400~750 oC. Their physicochemical features were characterized by TG/DSC, XRD and TEM techniques. Results showed that the Li4Ti5O12 phase with its crystal size of tens of nanometers was likely produced by the reaction between Li2TiO3 and orthorhombic TiO2 upon thermal treatment, and such reaction would be exothermic.

Abstract: In the present work, the microstructure and microwave dielectric properties of BaTi₄O₉ ceramics derived from a sol-gel precursor were presented. Density measuring results demonstrated that the largest densities of ceramic sample about 96.7% could be reached by virtue of a cool iso-static press and a sintering process at at 1300 °C for 6 hours. The dielectric constant (ε_r), quality factor (Q×f) and the temperature coefficients (τ_f) of the BaTi₄O₉ ceramic samples were 36.65, 28000 GHz, +20.2 ppm/°C, respectively. XRD, SEM and XPS were used to characterize the microstructure of the ceramics samples. Substantial Ti³⁺ was proposed to be the cause of dielectric loss.

Abstract: Anatase TiO₂ having high temperature stability and specific surface area was synthesized using a gel precursor in very mild conditions. The precursor gel was obtained by dialysis treatment of Na₁₆Ti₁₀O₂₈–HNO₃ solution. The samples were characterized by X-ray diffraction analysis, transmission electron microscopy, Brunner–Emmett–Teller method for specific surface area measurements, and thermogravimetric analysis.

Abstract: BaTiO₃–(Bi_1/2K_1/2)TiO₃ (abbreviated as BT-BKT) solid solution ceramics, as a lead-free PTC (positive temperature coefficient of resistivity) thermistor material usable over 130°C, has been synthesized by sintering in N₂ atmosphere and after annealing in air over 1200°C. In the BT-BKT ceramics with PTC property, the impedance/modulus spectroscopic plots have revealed that a third resistance-capacitance (RC) response besides grains and grain boundaries. Using the remote electron beam induced current (REBIC) configuration, imaging has revealed EBIC contrast consistent with the presence of negatively charged electrostatic grain boundary barriers in the BT-BKT semiconducting ceramics.