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Oleic acid/oleylamine capped Fe1-xPdx(x=0.16, 0.20, 0.25) nanoparticles have been synthesized using a diol as reducing agent in order to get nanoparticles of different average sizes and coatings. Composition and morphology were analyzed by infrared spectroscopy (IR), X-Ray Diffraction (RXD), thermogravimetry (TG) and Transmission Electron Microscopy (TEM). Well dispersed nanoparticles with uniform sizes between 3 and 8 nm and average diameters less than 6 nm were obtained. Magnetic properties were investigated by Electron Magnetic Resonance (EMR) and magnetization measurements. Most of the nanoparticles were superparamagnetic at physiological temperature with low magnetic saturation values (near 5 emu.g-1alloy/0.4 N per Fe atom). SAR measurements were also performed with the aim of carrying out hyperthermia measurements but the nanoparticles did not work as magnetic heaters.

The influence of the carbon content in LiFePO4/Ccomposites synthesized by the freeze-drying method was studied by varying the citric acid (chelating agent): Fe ratio. Diminishing this ratio from 1:1 to 0.33:1 led to a gradual reduction of the carbon content from 16.1 to 7.2% wt and different morphologies. Transmission electron microscopy micrographs of the composite with the greatest carbon percentage (16%) show mainly 30 nm LiFePO4particles homogeneously embedded in a carbon network. Samples containing less carbon exhibit only one type of morphology, 200–700 nm aggregates made up of an intimate mixture of LiFePO4particles and carbon. Galvanostatic cycling from 2 to 4 V vs Li/Li+evidences the typical LiFePO4redox behavior at 3.4 V, and a second contribution at 2.65 V probably related to the carbon content. At a high rate, a good specific capacity value is observed for the nanoparticulate sample (16% wt C), whereas poorer performance is observed for low carbon content samples (11 and 7.2 wt % C). Heterogeneous and insufficient carbon covering together with phosphate particle aggregation in these latter samples can account for this behavior. Two carbon distribution models are proposed to explain different electrochemical responses. In all cases, a good capacity retention is observed after prolonged cycling.