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Sol-gel synthesis and characterisation of nanocrystalline gahnite

Nanosized zinc aluminate spinel (gahnite, ZnAl2O4) powder was prepared by sol– gel technique at low sintering temperatures. The dried gel and thermally treated samples were characterized by means of Differential Thermal Analysis and Thermo-Gravimetric Analysis (DTA, TGA), X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). The surface area was measured by a Brunauer-Emmet-Teller (BET) adsorption-desorption isotherms. Zinc aluminate spinel powder was produced by gel heat-treatment at temperatures as low as 300 °C. The average gahnite crystallite size for the samples sintered in the temperature range of 400– 1000 °C has been calculated by means of Scherrer equation revealing nanocrystalline powders were prepared. TEM micrograph of sample sintered at 700 °C for 2 h showed nano-sized particles with high level of agglomeration. The average particle sizes obtained using XRD, TEM and B.E.T studies were compared.

crystallite size; crystallization; gahnite; sol-gel synthesis

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