Li 2 MnSiO 4 is a promising cathode material for lithium ion rechargeable batteries, however, synthesizing the desired crystallographic phase is challenging. We report the synthesis and electrochemical charge/ discharge studies of carbon coated nanostructured Li 2 MnSiO 4 in orthorhombic and monoclinic crystallographic phases. Li 2 MnSiO 4 has been synthesized using solid state and sol-gel processes in bulk and nano-geometries without and with carbon coatings. The electrochemical performance of these Li 2 MnSiO 4 samples was measured at a C/20 charge/discharge rate within 1.
A major challenge in the field of up-converting (UC) nanomaterials is to enhance their efficiencies. The-OH defects on the surface of the nanoparticles are thought to be the main cause of luminescence quenching, but there are no comparative studies in the literature showing the impact of anhydrous versus hydrous synthesis on up-conversion efficiency. In this article, we present the synthesis of up-converting NaGdF4: Yb +3 , Tm +3 nanoparticles by two different methods: Thermal decomposition of single source metal-organic anhydrous precursors [NaLn(TFA)4(diglyme)] (Ln 2 = Gd, Tm, Yb; TFA = trifluoroacetate) and room temperature co-precipitation using hydrated inorganic salts Ln(NO3)3ꞏ5H2O (Ln = Gd, Tm, Yb), NaNO3 and NH4F in ethylene glycol. After a detailed study on the influence of solvents and the percentage of lanthanide dopant on the crystal phase of the up-converting nanoparticles (NPs) and their complete characterization, a comparative up-conversion study was carried out which revealed that the uniform nanospheres (av. size ~13 nm) obtained from the anhydrous SSP had significantly higher up-conversion efficiency than agglomerated nanorods (~197 nm in length and ~95 nm in width) produced from hydrated inorganic salts. An enhanced up-conversion quantum yield of 1.8% for the anhydrous sample validates the anhydrous precursor approach as a strategy to obtain small but highly emitting upconverting particles without requiring a silica or undoped matrix surface passivation layer.
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