9 resultados para ilmenite

em Deakin Research Online - Australia


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Carbo-thermic reduction of ilmenite (FeTiO3) to TiO2 and/or TiC is traditionally carried out by a high temperature annealing treatment at  ~1500 °C. In this work, electric discharge assisted mechanical milling (EDAMM) has been used to synthesise TiC + Fe3C from FeTiO3 in 5 min. In this study we report of the reduction of FeTiO3 with C that does not require an additional high temperature annealing treatment.

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One dimensional titanium oxides (TiO2) nanorods and nanowires have substantial applications in photocatalytic, nanoelectronic, and photoelectrochemical areas. These applications require large quantities of materials and a production technique suitable for future industry fabrication. We demonstrate here a new method for mass production of TiO2 nanorods from mineral ilmenite sands (FeTiO3). In this process, powder mixtures of ilmenite and activated carbon were first ball milled; the milled samples were then heated twice at two different temperatures. First high-temperature annealing produced metastable titanium oxide phases, and subsequent second low-temperature annealing in N2-5%H2 activates the growth of rutile nanorods. This solid-state growth process allows large-quantity production of rutile nanorods.

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Growth mechanisms of TiO2 nanorods synthesized from mineral ilmenite using ball milling and annealing method have been systematically investigated. Two annealing processes are needed to grow the nanorods. The heating rate and gaseous environment in the first annealing step are critical to the formation of intermediate phases; these and the annealing atmosphere in the second heating play very important roles in nanorod growth. One-dimensional growth of the nanorods induced by low-temperature annealing in nitrogen plus hydrogen is possibly driven by atom vacancy diffusion in addition to surface diffusion.

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Pronounced and stable pseudocapacitance has been found in flowerlike FeTiO3 nanostructures that were synthesized from ball-milled ilmenite (natural mineral) under mild hydrothermal conditions. Each nanoflower is composed of many thin petals with a thickness of 5–20 nm and a width of 100–200 nm. The formation of these flowerlike nanostructures is attributed to a dissolution–precipitation mechanism involving an intermediate sodium-containing phase. Electrochemical properties of the obtained FeTiO3 nanostructures are evaluated in aqueous electrolytes. The capacitance of 122 ± 14.5 F/g is measured in 1 M KOH aqueous electrolyte at the current rate of 500 mA/g, and 50 ± 6 F/g is retained at 5 A/g. The material has good long-term cycling stability. According to our data, FeTiO3 nanostructures show functionality as an electrode material for supercapacitors.