Simple Co-precipitation Process Research Articles

High rate performance of novel cathode material Li 1.33Ni 1/3Co 1/3Mn 1/3O 2 for lithium ion batteries

Li 1.33Ni 1/3Co 1/3Mn 1/3O 2 with highly ordered structure has been successfully synthesized via a simple co-precipitation process. Charge–discharge tests showed that the initial discharge capacities are 153.0 mAh g −1 and 128.9 mAh g −1 at 5 C (1000 mA g −1) and 10 C (2000 mA g −1) between 2.5 and 4.5 V, respectively. The average full-charge time of this material is less than 12 min at 5 C and 6 min at 10 C. The electrode material composed of the prepared showed a better cyclability. The excellent high rate performance is attributed to the improved ordered layered structure and the electrical conductivity. The excess Li shorten Li + diffusion distance between these submicron and nano-scaled particles. The results show that Li 1.33Ni 1/3Co 1/3Mn 1/3O 2 cathode material has potential application in lithium ion batteries.

Synthesis and crystallization behavior of 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) nanosized powders prepared using a simple co-precipitation process

The synthesis and crystallization behavior of 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) nanopowders prepared using a simple co-precipitation process at 348 K and pH = 7 were investigated using differential scanning calorimetry/thermogravimetry (DSC/TG), an X-ray diffractometer (XRD), the Raman spectra, transmission electron microscopy (TEM), selected area electron diffraction (SAED), and an energy dispersive spectrometer (EDS). The activation energy of tetragonal ZrO 2 crystallization from 3Y-TZP freeze-dried precursor powders using a non-isothermal method, namely, 169.2 ± 21.9 kJ mol −1, was obtained. The growth morphology parameter n was approximated as 2.0, which indicated that it had a plate-like morphology. The XRD, Raman spectra, and SAED patterns showed that the phase of the tetragonal ZrO 2 was maintained at 1273 K. The crystallite size of 3Y-TZP freeze-dried precursor powders calcined at 1273 K for 5 min was 21.3 nm.

Influence of morphological transformation on luminescence properties of europium-doped gadolinium oxide nanostructures

Low dimensional europium (Eu3+)-doped gadolinium oxide (Gd2O3) lanthanide nanostructures are synthesized by an effective and simple coprecipitation process followed by subsequent heat treatments. Transmission electron microscope (TEM) images indicate Eu3+-doped Gd2O3 nanostructures undergo significant morphological changes from nanorods to nanoparticles during thermal treatments. Nanostructures with different morphology, including nanotubes, strongly influence the photoluminescence properties. The dependence of luminescence lifetime on morphological nature of the nanostructures demonstrates that the one dimensional nanostructures such as nanorods and nanotubes have higher emission intensity with shorter lifetime. Our analysis suggests that the morphological transformation of the nanostructures plays the most important role in the behavior of radiative and nonradiative relaxation mechanisms, resulting in the overall photoluminescence properties.

Magnetic polyorganosiloxane core–shell nanoparticles: Synthesis, characterization and magnetic fractionation

Abstact Here, we present the synthesis, characterization and magnetic separation of magnetic polyorganosiloxane nanoparticles. Magnetic iron oxide nanoparticles with average particle radii of 3.2 nm had been synthesized by a simple coprecipitation process of iron(II) and iron(III) salt in basic solution. Afterwards, the particles were successfully incorporated into a polyorganosiloxane network via a polycondensation reaction of trimethoxymethylsilane (T), diethoxydimethylsilane (D) and the functional monomer (chloromethylphenyl)trimethoxysilane (ClBz-T) in aqueous dispersion. A core–shell system was chosen to increase the flexibility of the system concerning size, composition and functionalization possibilities. The magnetic nanocapsules with particle radii below 60 nm were separated from non-magnetic material with a high effectiveness by the use of commercially available separation columns which are commonly used for isolation of microbeads and subsequently characterized via transmission electron microscopy (TEM), asymmetrical flow field-flow fractionation (AF-FFF), superconducting quantum interference device (SQUID) and Mossbauer spectroscopy.

Fabrication and Characterization of Indium Tin Oxide−Carbon Nanotube Nanocomposites

Nanocrystals of two indium tin oxide (ITO) polymorphs (rhombohedral and cubic) were deposited on the sidewalls of the multiwalled carbon nanotubes (MWCNTs) by a simple coprecipitation process. X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscope (HRTEM) images, select area electron diffraction patterns (SAED), and energy-dispersive X-ray (EDX) spectroscopy were used to characterize the as-prepared samples. The results indicated that tuning of the ITO phase in the nanocomposites can be selectively achieved via controlling the pH value of the coprecipitation process and the temperature of the subsequent calcination. The formation mechanism of the ITO/MWCNT nanocomposites was also investigated. Electrical conductivity measurements on the samples pressed into pellets showed that the maximum conductivities attained were 0.52 ± 0.05 and 0.65 ± 0.04 S·cm−1 for the rhombohedral and cubic ITO/MWCNT nanocomposites, respectively, at a dopant concentration of 12.5 wt %. The electrical conductivity of the nanocomposites was significantly enhanced compared to the pristine MWCNTs.

High efficient ultraviolet photocatalytic activity of BiFeO3 nanoparticles synthesized by a chemical coprecipitation process

Single-crystalline BiFeO3 nanoparticles have been synthesized through a simple chemical coprecipitation process using bismuth and iron nitrates. By employing both X-ray diffraction and electron diffraction, the nanoparticles were unambiguously identified to have a rhombohedrally distorted perovskite structure. X-ray photoelectron spectroscopy investigation shows that Fe element exists as the Fe3+ valence state in the BiFeO3 nanoparticles. UV–Vis absorption spectrum indicates that the absorption cut-off wavelength of the nanoparticles is about 580 nm, corresponding to the energy bandgap of 2.10 eV. The BiFeO3 nanoparticles exhibited an efficient ultraviolet photocatalytic activity, more than 92% of methyl orange was decolorized after 260 min UV irradiation. Unexpectedly, the BiFeO3 nanoparticles do not show any efficient visible light photocatalytic activity, although the nanoparticles absorb visible light in the wavelength range of 400–580 nm.

Luminescent Properties of Y2(MoO4)3:Eu3+ Red Phosphors with Flowerlike Shape Prepared via Coprecipitation Method

Novel Y2(MoO4)3:Eu3+ red phosphors were synthesized through a simple coprecipitation process and characterized by using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and fluorescent spectrophotometry. The results of XRD and FE-SEM show that resultant samples are single phase and have flowerlike shape. In the excitation spectra of Y2(MoO4)3:Eu3+ phosphors, by monitoring 616 nm, the charge transfer bands (CTB) of Eu3+→O2- and Mo6+→O2- centering at around 264 and 310 nm can be observed, respectively. Moreover, the intensity ratio of charge transfer band between Eu3+→O2- and Mo6+→O2- increases with increasing Eu3+ ions doping concentration. The characteristic red emission at around 616 nm of Eu3+ ions is also observed, ascribed to the 5D0→7F2 transition of Eu3+ ions, and the optimal doping concentration is 12 mol %. Finally, the Ωλ (λ = 2 and 4) intensity parameters and Huang−Rhys factor were also calculated according to Judd−Ofelt theory and multiphonon relaxation theory, respectively.

Preparation and Characterization of Nanosized Bi4Ti3O12 Powders

Nanosized Bi4Ti3O12 (BIT) powders were prepared by a simple coprecipitation process. Differential scanning calorimetry (DSC) measurement was carried out to estimate the phase transition temperatures of the BIT powders calcined at different temperatures. The results showed a range of coexistence of the BIT and Bi2Ti2O7 phases at calcination temperatures from 600 to 650 °C. The dielectric constants of ball-milled BIT powders calcined at different temperatures were measured. It was found that the samples had a value of around 190, which is higher than that of BIT bulk ceramics.