Fast and simultaneous doping of Sr0.9-x-y-zCa0.1In2O4:(xEu3+, yTm3+, zTb3+) superstructure by ultrasonic spray pyrolysis.

In the present work, Sr0.9-x-y-zCa0.1In2O4:(xEu3+, yTm3+, zTb3+) particles were synthesized by the ultrasonic spray pyrolysis (USP) method to obtain a single-phase white phosphorus formed by six different cations in solution within the lattice (superstructure). The samples were also structurally and morphologically characterized by X-ray diffraction (XRD) techniques and by field emission scanning electron microscopy (FE-SEM). The photoluminescent behavior and the characteristics of the emitted colors were studied by the variation in the co-doping of the rare earth elements. The Sr0.9Ca0.1In2O4 sample showed a near blue color emission, but all co-doped samples showed emission in white with very close chromaticity coordinates to the standard white (x = 0.33 and y = 0.33). The Tm3+ → Tb3+ (ET1), Tm3+ → Eu3+ (ET2) and Tb3+ → Eu3+ (ET3) Energy Transfers were proposed and are considered necessary for adjusting and controlling the desired color properties.

Adsorbent 2D and 3D carbon matrices with protected magnetic iron nanoparticles.

We report on the synthesis of two and three dimensional carbonaceous sponges produced directly from graphene oxide (GO) into which functionalized iron nanoparticles can be introduced to render it magnetic. This simple, low cost procedure, wherein an iron polymeric resin precursor is introduced into the carbon framework, results in carbon-based materials with specific surface areas of the order of 93 and 66 m(2) g(-1), compared to approx. 4 m(2) g(-1) for graphite, decorated with ferromagnetic iron nanoparticles giving coercivity fields postulated to be 216 and 98 Oe, values typical for ferrite magnets, for 3.2 and 13.5 wt% Fe respectively. The strongly magnetic iron nanoparticles are robustly anchored to the GO sheets by a layer of residual graphite, on the order of 5 nm, formed during the pyrolysis of the precursor material. The applicability of the carbon sponges is demonstrated in their ability to absorb, store and subsequently elute an organic dye, Rhodamine B, from water as required. It is possible to regenerate the carbon-iron hybrid material after adsorption by eluting the dye with a solvent to which it has a high affinity, such as ethanol. The use of a carbon framework opens the hybrid materials to further chemical functionalization, for enhanced chemical uptake of contaminants, or co-decoration with, for example, silver nanoparticles for bactericidal properties. Such analytical properties, combined with the material's magnetic character, offer solutions for environmental decontamination at land and sea, wastewater purification, solvent extraction, and for the concentration of dilute species.

Synthesis of mesoporous silica with embedded nickel nanoparticles for catalyst applications.

Here we describe a new route for the synthesis of nanometric Ni particles embedded in a mesoporous silica material with excellent potential for catalytic applications. Mesoporous silica with a surface area in the range of 202-280 m2/g, with narrow pore size distribution and Ni nanoparticles (particles in the range of 3-41 nm) were obtained in a direct process. A different approach was adopted to process such a nanocomposite. This new approach is based on the formation of a polymer with the silicon oxianion and nickel cation chelated to the macromolecule structure and on the control of the pyrolysis step. The CO/CO2 atmosphere resulting from the pyrolysis of the organic material promotes the reduction of the Ni citrate.

Application of Ni:SiO2 nanocomposite to control the carbon deposition on the carbon dioxide reforming of methane.

Stable Ni nanoparticles embedded in a mesoporous silica material were used as catalysts for the conversion of methane into synthesis gas. This catalyst has the singular properties of controlling the carbon deposition and deactivation of active sites. A comparative study of our nanocomposites with conventional catalysts showed that impregnation material presented a preferential encapsulation and growth of carbon nanotubes on the metal surface. The impregnated catalyst showed a higher tendency for carbon nanotube and whiskers formation.

Synthesis of metal-oxide matrix with embedded nickel nanoparticles by a bottom-up chemical process.

Here we describe a new chemical route for obtaining highly dispersed nanometric Ni particles embedded in different matrices based on Al2O3, MgO, and TiO2 and in the heterogeneous matrices CeO2-doped Al2O3 and MgO-doped Al2O3. The synthesis method is based on a modification of the polymeric precursor method. The Ni nanoparticles (particles in the range of 1-40 nm) were obtained in a single process, without the use of an external reducing agent (hydrogen atmosphere).

Nanofiller loading level: Influence on selected properties of an adhesive resin.

OBJECTIVES: To evaluate the effect of the filler content in the cohesive strength (sigma), Weibull modulus (m) and degree of conversion (DC) of an experimental adhesive system. METHODS: A HEMA/Bis-GMA/TEGDMA-based adhesive was formulated and filled with silica nanofillers in the following weight percentages (wt%): R0=0%; R1=1%; R3=3%; R5=5% and R10=10%. The adhesive of Adper Scotchbond Multi-Purpose (SBMP) system was used as a commercial reference. Twenty dumbbell-shaped specimens with cross-sectional area of 0.5mm(2) were made per group and tensile tested with a crosshead speed of 0.5mm/min until fracture. The cohesive strength was calculated in MPa. DC was obtained through FTIR after light curing for 25s. Data were submitted to one-way ANOVA and Tukey's test (alpha=0.05) and to Weibull analysis. RESULTS: Mean sigma results were: R0=65.4+/-8.4; R1=73.2+/-8.8; R3=72.0+/-8.4; R5=73.1+/-9.7; R10=85.5+/-13.1 and SBMP=79.0+/-11.0MPa. R10 presented the highest sigma, while R0 showed the lowest. R5 and SBMP did not differ significantly (p<0.05). Weibull analysis revealed no significant difference in structural reliability between groups. The experimental adhesives presented similar results of DC, which, in turn, were significantly higher than the SBMP. CONCLUSIONS: The addition of 10% filler in weight improves the cohesive strength of the adhesive, not interfering in the structural reliability or the degree of conversion.