A novel method for the preparation of non-agglomerated nanometre sized particles of lanthanum phosphate phosphors utilising a high surface area support in the firing process

This journal is © The Royal Society of Chemistry 2012A convenient method is described that uses a quartz wool substrate to immobilise nanometre sized phosphor precursor particles enabling them to be fired at high temperature without sintering/agglomeration. The nanometre sized phosphor particles are easily removed from the substrate by re-dispersion into liquid for subsequent use.Biotechnology and biological sciences research council (BBSRC

Preparation and characterization of stable aqueous suspensions of up-converting Er3+/Yb3+-doped LiNbO3 nanocrystals

The preparation of LiNbO3:Er3+/Yb3+ nanocrystals and their up-conversion properties have been studied. It is demonstrated that polyethyleneimine- (PEI) assisted dispersion procedures allow obtaining stable aqueous LiNbO3:Er3+/Yb3+ powder suspensions, with average size particles well below the micron range (100–200 nm) and the isoelectric point of the suspension reaching values well above pH 7. After excitation of Yb3+ ions at a wavelength of 980 nm, the suspensions exhibit efficient, and stable, IR-to-visible (green and red) up-conversion properties, easily observed by the naked eye, very similar to those of the starting crystalline bulk material

Synthesis and Characterizations of YVO₄:Eu Colloids

International audienceWe present a new process for the synthesis of colloidal europium-doped yttrium vanadate with a particle diameter of about 10 nm. Nanocrystals are produced by precipitation of citrate complexes of rare-earth salts with sodium orthovanadate. NMR and IR studies show that the interaction between citrate ligands and lanthanide ions limits the growth of particles and ensures the stability of the colloidal solutions through electrostatic and steric repulsions. The optimized process leads to stable and highly concentrated transparent colloidal solutions in water (up to 400 g‚L-1)

Nonclassical Crystallization and Size Control of Ultra-Small MoO2 Nanoparticles in Water

International audienceSize tuning for MoO2 nanoparticles is demonstrated for the first time over a wide range 2-100 nm, through a colloidal route into water. A nucleation-growth mechanism based on oriented attachment is evidenced to rationalize the impact of two simple synthetic levers: reactant ratio and temperature. The smallest non-aggregated crystalline MoO2 nanoparticles are reported, with specific surface area reaching 86 m(2) g(-1). Size and morphology control, along with the ability to produce, non-aggregated ultra-small MoO2 particles are important for a wide range of applications, such as catalysis and energy storage. To exemplify the importance of size tuning, the impact of downscaling on the electrochemical properties in Li-ion batteries is investigated

Sustainable one-pot aqueous route to hierarchical carbon-MoO2 electrodes for Li-ion batteries

International audienceA route towards carbon-MoO2 core-shell spheres has been developed, through hydrothermal decomposition of ascorbic acid combined with precipitation of MoO2 nanoparticles. In this one-pot and green process, carbon spheres originating from ascorbic acid act as seeds for the in situ deposition of a corona made of 30 nm molybdenum dioxide particles. The as-obtained hierarchical nanostructured carbon-MoO2 core-shell spheres exhibit an ideal combination of electrical conductivity and lithium reactivity for Li-ion battery electrodes. This nanocomposite offers the opportunity to master the collector-active material and active material-electrolyte interfaces. Direct transfer ``from the beaker to the battery'' without any additives nor thermal treatment yields storage capacity values of ca. 600 mA h g(-1) at C/5 rate with excellent stability that challenges state-of-the-art molybdenum oxide-based batteries