Preparation of (Pb,Ba)TiO3 powders and highly oriented thin films by a sol-gel process

Solid solution Pb1-xBaxTiO3, with particular emphasis on Pb0.5Ba0.5TiO3, was prepared using a sol-gel process incorporating lead acetate trihydrate, barium acetate, and titanium isopropoxide as precursors, acetylacetone (2,4 pentanedione) as a chelating agent, and ethylene glycol as a solvent. The synthesis procedure was optimized by systematically varying acetylacetone: Ti and H2O:Ti molar ratios and calcination temperature. The resulting effects on sol and powder properties were studied using thermogravimetric analysis/differential scanning calorimetry, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller analysis, and x-ray diffraction (XRD). Crystallization of the perovskite structure occurred at a temperature as low as 450 °C. Thin films were prepared by spin coating on (100) MgO. Pyrolysis temperature and heating rate were varied, and the resultant film properties investigated using field-emission scanning electron microscopy, atomic force microscopy, and XRD. Under optimized conditions, highly oriented films were obtained at a crystallization temperature of 600 °C

Prediction the concentration of graphite direct exfoliation by liquid solution with solubility parameters map

This study is to discuss solvent selection with graphene dispersion concentration of directly exfoliation graphite. That limiting boundaries of fractional cohesion parameters will be draw on the triangular diagram to prediction and estimate. It is based on the literature of data and check with experimental or other literature results, include organic solution, aqueous solution and ionic liquid. In this work, we found that estimated the graphene dispersion concentration by distance (Ra) of Hansen solubility parameters (HSP) between graphene and solvent, the lower Ra; the higher concentration, some case the lower Ra; the lower dispersion concentration (such as acetone). It is compatible with the graphene dispersion concentration on the Hansen space or Triangular fractional cohesion parameters dispersion diagram. From Triangular fractional cohesion parameters dispersion diagram, 2D maps are more convenient for researchers than 3D maps of Hansen space and quickly to find the appropriate combination of solvents for different application

Optimization of the experimental conditions for the preparation of a thin strontium titanate film by hydrothermal process

A Taguchi orthogonal array design was implemented to optimize the experimental conditions for the preparation of a thin strontium titanate film on a Ti substrate using a hydrothermal process. The effects of such preparatory conditions as the strontium-concentration, pH-value, reaction temperature, reaction time and the substrate surface treatment were systematically studied. Results indicate that the effects of the reaction temperature and reaction time are the key variables influencing the relative crystal intensity (intensity of (110) SrTiO₃ peaks in XRD spectrum/intensity of (101) Ti peak in XRD spectrum) of the films obtained. By combining the optimal settings of the two most influential process variables, a polycrystalline, SrTiO₃-films was obtained, with improved crystallinity and a grain size of 0.2–0.4 μm and a dielectric constant of 360 at I MHz

Optimization of the experimental conditions for the preparation of a thin strontium titanate film by hydrothermal process

A Taguchi orthogonal array design was implemented to optimize the experimental conditions for the preparation of a thin strontium titanate film on a Ti substrate using a hydrothermal process. The effects of such preparatory conditions as the strontium-concentration, pH-value, reaction temperature, reaction time and the substrate surface treatment were systematically studied. Results indicate that the effects of the reaction temperature and reaction time are the key variables influencing the relative crystal intensity (intensity of (110) SrTiO₃ peaks in XRD spectrum/intensity of (101) Ti peak in XRD spectrum) of the films obtained. By combining the optimal settings of the two most influential process variables, a polycrystalline, SrTiO₃-films was obtained, with improved crystallinity and a grain size of 0.2–0.4 μm and a dielectric constant of 360 at I MHz

Hierarchical Porous Heteroatoms—Co-Doped Activated Carbon Synthesized from Coconut Shell and Its Application for Supercapacitors

Coconut husk biomass waste was used as the carbon precursor to develop a simple and economical process for the preparation of hierarchical porous activated carbon, and the electrochemical properties of the electrode material were explored. The important process variables of carbonization, the weight ratios of the coconut shell/KOH, the amount of source dopant, and the carbonization temperature were investigated in order to reveal the influence of the as-obtained microporous/mesoporous/macroporous hierarchical porous carbon materials on the powder properties. Using a BET specific surface area analyzer, Raman analysis, XPS and SEM, surface morphology, pore distribution and specific surface area of the hierarchical porous carbon materials are discussed. The results show that the as-prepared N-, S- and O-heteroatom-co-doped activated carbon electrode was manufactured at 700 °C for electrochemical characteristics. The electrochemical behavior has the characteristics of pseudo-capacitance, and could reach 186 F g−1 at 1 A g−1 when measured by the galvanostatic charge–discharge (GCD) test. After 7000 cycles of the charge–discharge test, the initial capacitance value retention rate was 95.6%. It is predicted that capacitor materials made when using coconut shell as a carbon source will have better energy storage performance than traditional carbon supercapacitors

Solvothermal Synthesis of TiO2 Photocatalysts in Ketone Solvents with Low Boiling Points

The titanium dioxide (TiO2) photocatalysts were synthesized by a solvothermal process in highly alkaline 70 : 30 water : ketone solutions with a TiO2-P25 precursor and calcined at different temperatures. The ketone solvents, such as acetone and methyl ethyl ketone (MEK), had low boiling points (<100°C). The as-prepared samples were characterized by XRD, TEM, FTIR, UV-vis and Raman spectroscopy. The effects of the different solvents on the nanostructure, the morphology, and the photocatalytic performance of the TiO2 products were investigated. Nanotubes formed in water and water-MEK, while nanoparticle/nanowires formed in water-acetone and water-acetone-MEK. The ketone solvents played an important role in the improving nanostructure properties of these products, which affected their photocatalytic reactions. The results indicated that samples synthesized in solvents such as water and MEK had high adsorption and photocatalytic behaviors. The photocatalytic reactivity was the greatest for the TiO2 prepared in MEK and calcined at 100°C, which was even more reactive than the sample prepared in water and TiO2-P25 powder

Preparation and Application of Titanate Nanotubes on Dye Degradation from Aqueous Media by UV Irradiation

Titanate nanotubes were synthesized by a hydrothermal method using commercial TiO2 powder and then used as a photocatalyst. The titanate nanotubes were synthesized by varying the hydrothermal temperature from 110°C to 180°C. The morphological changes and phase transformation of the TiO2 nanotubes were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The particles’ scattering behavior was investigated by Raman studies, and the surface area of the nanotubes was determined by a Brunauer, Emmett, and Teller (BET) analysis. Comparative studies show that the surface area of nanotubes increases with increasing temperature up to 130°C. The catalytic behavior of the synthesized nanotubes was also studied. The as-prepared titanate nanotubes were applied to methylene blue (MB, an organic dye) degradation in aqueous media by UV irradiation. Approximately 99% of the dye was removed from the aqueous media using 2 g/L titanate nanotube when the initial dye concentration was 9 mg/L. The total irradiation time was 2 h