Red-emitting AlN:Mn2+ phosphors prepared by combustion synthesis

CeO2-based solid solutions in which Pd partially substitutes for Ce attract considerable attention, owing to their high catalytic performances. In this study, the solid solution (Ce1−xPdxO2−δ) with a high Pd content (x ~ 0.2) was synthesized through co-precipitation under oxidative conditions using molten nitrate, and its structure and thermal decomposition were examined. The characteristics of the solid solution, such as the change in a lattice constant, inhibition of sintering, and ionic states, were examined using X-ray diffraction (XRD), scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM−EDS), transmission electron microscopy (TEM)−EDS, and X-ray photoelectron spectroscopy (XPS). The synthesis method proposed in this study appears suitable for the easy preparation of CeO2 solid solutions with a high Pd content.

A series of Bi4O5Br2 photocatalysts were prepared via an innovation method of synthesis with ionic liquids (ILs). The crystal structures were investigated by X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR). The Field Emission Scanning Electron Microscope (FE-SEM) images illustrated the unique structure of prepared photocatalysts. The photocatalysts were also characterized by N2 adsorption-desorption analysis, X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectra (UV-vis/DRS) and photoluminescence spectra (PL). The role of ILs in synthesis of Bi4O5Br2 on morphology and photocatalytic properties were investigated. Rhodamine B, 5-fluorouracil and chromium (VI) were used as the model micropollutants to evaluated adsorption capacity, photooxidation and photoreduction ability of prepared Bi4O5Br2 under artificial solar light. This work provided a new thought for enhanced photocatalytic activity of bismuth oxybromide photocatalysts.

LiAl0.1Mn1.9O4 materials were prepared by a solution combustion synthesis method. In order to improve the purity of the products, the effect of further calcination time was investigated. The phase compositions of the as-prepared products were determined by X-ray diffraction (XRD). The electrochemical performance of the products was tested by using a coin-type half battery versus lithium metal foil as anode material. XRD results suggested that the main phase of the products was LiAl0.1Mn1.9O4, and there was a trace amount Mn2O3 impurity in some of the products. The purity, crystallinity and grain size of the LiAl0.1Mn1.9O4 were increased with increasing further calcination time. Electrochemical experiments demonstrate that the initial discharge capacities of the products with further calcination time of 0, 6, 12 and 24h were 93.7, 105.7, 114.0 and 120.6mAh/g, and about 89.8, 89.5, 89.2 and 88.3% of the initial capacities were retained after 25 cycles, respectively. Further calcination time can enhance the initial capacity, but is not favorable for the cycle ability of the products.

In this paper, LiNixMn2−xO4 materials were prepared by solution combustion synthesis method using acetic salts as raw materials and acetic acid as fuel. The phase structures are characterized by X-ray diffraction (XRD). Electrochemical performances of the materials are investigated by galvanostatic charge/discharge methods. XRD results revealed that the main phase of the products with increasing Ni3+ content is LiMn2O4, and there is a trace amount of Mn3O4 found in the product with Ni3+ content of 0.05. Electrochemical experiments showed that the capacity and the cyclability of the LiNixMn2−xO4 materials decrease with increasing Ni3+ content. Ni3+ doping has no significantly improvement for the capacity and the cyclability of the LiMn2O4 spinel.

Graphene is one of the most promising materials discovered in last years. It is usually synthesized by Hummers’ method requiring the usage of many chemicals. As an alternative to traditional methods, in this study a bottom-up synthesis method was developed from various saccharides such as starch, mannose, cellulose, fructose, arabinose, and xylose by carbonization at 600 °C to 800 °C in LiCl/KCl molten salt system. The proposed method is environmental friendly and economic. Graphene yields at 600 °C are higher than at 800 °C. Graphene products give peak at 2θ = 23° on the X-Ray Diffraction (XRD) patterns. As the temperature is increased, amorph structure is observed on the XRD patterns. Raman spectroscopy results show that intensity of D band peak over intensity of G band peak (ID/IG) values of graphene products synthesized from arabinose and cellulose at 600 °C, graphene from arabinose synthesized at 800 °C are 0.76, 0.65 and 0.85 respectively, which show that these products are few-layered. According to X-ray photoelectron spectroscopy (XPS) results, graphene products synthesized at 600 °C have higher carbon content than those synthesized at 800 °C.

The Nano-HA powder were synthesized by chemical precipitation with Ca(H2PO4)2•H2O and Ca (OH)2 and porous HA was prepared by sintering with magnesium as pore-creator. Nano-HA powder and porous HA were characterized by wide angle X-ray diffraction, transmission electron microscopy(TEM), scanning electron microscopy (SEM), SEM in combination with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray photoelectron spectroscopy. The experimental results show that HA powder synthesized by chemical precipitation is nanometer powder. Magnesium was ideal pore-creator for preparation of porous materials. The grain size of porous HA was sub-micron and MgO which existed in the grain boundary of HA as a second phase particles that played the roles of inhibiting the HA grain growth.

Titanium dioxide materials were synthesized using two different methods. The samples were characterized by X-ray diffraction (XRD), UV–Visible diffusion reflectance spectroscopy (UV-Vis DR), Raman spectroscopy, N2 adsorption/desorption, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron spectroscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Although both kind of materials were found to have mesoporous structure and anatase crystalline phase, one of them was obtained from a synthesis method that does not involve the use of surfactants, and therefore, does not require calcination at high temperatures. This implies that the synthesized solid was self-doped with carbon species, coming only from the same source used for titanium. Then, the relationship between the presence of these species, the final calcination temperature, and the photocatalytic activity of the solids was studied in terms of the degradation and mineralization of an Acid Orange 7 aqueous solution, under visible radiation. A photosensitizing effect caused by the non-metal presence, that allows the solid to extend its absorption range, was found. Hence, a novel route to prepare C-modified photoactive mesoporous TiO2, simpler and cheaper, where neither a template nor an external carbon source is used, could be performed.

This work reports the preparation of La2O3 uniformly doped Mo nanopowders with the particle sizes of 40–70 nm by solution combustion synthesis and subsequent hydrogen reduction (SCSHR). To reach this aim, the foam-like MoO2 precursors (20–40 nm in size) with different amounts of La2O3 were first synthesized by a solution combustion synthesis method. Next, these precursors were used to prepare La2O3 doped Mo nanopowders through hydrogen reduction. Thus, the content of La2O3 used for doping can be accurately controlled via the SCSHR route to obtain the desired loading degree. The successful doping of La2O3 into Mo nanopowders with uniform distribution were proved by X-ray photon spectroscopy and transmission electron microscopy. The preservation of the original morphology and size of the MoO2 precursor by the La2O3 doped Mo nanopowders was attributed to the pseudomorphic transport mechanism occurring at 600 °C. As shown by X-ray diffraction, the formation of Mo2C impurity, which usually occurs in the direct H2 reduction process, can be avoided by using the Ar calcination-H2 reduction process, when residual carbon is removed by the carbothermal reaction during Ar calcination at 500 °C.

The aim of this work is the synthesis of α-tricalcium phosphate by solution combustion synthesis using urea as combustible in the stoichiometric ratio and with excess of combustible. The salts Ca(O3)2.4H2O and (H4)2HPO4 were used as reaction precursors with Ca/P ratio of 1.5. The pH adjustment was made adding nitric acid. A porous foam composed by β-tricalcium phosphate, hydroxyapatite and α or β-dicalcium pyrophosphate were obtained as reaction product. X-ray diffraction was used to identify the phases. The obtainment of α-TCP was possible after a heat treatment where the material was held at 1250°C for 15 hours followed by quenching. Smaller particle size was obtained when four times the stoichiometric ratio of combustible was used in the reaction. α-TCP samples were immersed in SBF in order to verify the biocompatibility.

Sodium montmorillonite (MMT) was chosen as the carrier; a serial of CdS/TiO2-MMT nanocomposites with enhanced visible-light absorption ability was prepared by hydrothermal synthesis method combination with semiconductor compound modification method. The samples are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ultraviolet visible (UV-Vis) spectroscopy; the results showed that TiO2and CdS nanoparticles were loaded on the surface of montmorillonite uniformly. N2adsorption-desorption experiment showed that the specific surface area of TiO2/montmorillonite nanocomposite made by this method can reach 200 m2/g and pore-size distribution was from 4 to 6 nm; UV-Vis showed that the recombination of CdS and TiO2enhanced visible-light absorption ability of samples of TiO2/montmorillonite and visible-light absorption ability increase with the increased of the adsorption of CdS.