Spinets from gelatine-protected gels

Abstract

An organic–inorganic method of synthesis based on protected gels of inorganic salts in a gelatine matrix is presented. Spinel (MgAl₂O₄), franklinite (ZnMn₂O₄) and hetaerolite (MnFe₂O₄) spinet crystalline phases have been obtained by a simple process which involves homogeneous gels generated by a gelatine matrix added to the aqueous solution of precursor salts. The resulting gelatine-protected gel route is compared with a classical coprecipitation route including hydroxide, sulfide or oxalate coprecipitation. The amorphous gelatine-protected gels show a similar or slightly greater reactivity and the resulting spinel shows a microstructure with aggregates of particles, whose particle size is larger for gelatine samples. However, no differences are observed in their crystallite size and crystallographic cell parameters. Therefore, the gelatine-protected gels provide an easy route with a reactivity and subsequent microstructure comparable to the classical coprecipitation routes for the synthesis of spinels.