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Abstract

Gels based on a network of oxygen-bridged metal and/or semi-metal atoms and produced using a hydrolytic sol-gel process are often not homogeneous. Known non-hydrolytic sol-gel processes give rise to gels containing halogen. A novel non-hydrolytic sol-gel process has been found which gives rise to halogen-free and homogeneous gels and to xerogels obtainable therefrom. In this process, one or more compounds (I) from the series of metal or semi-metal alkoxides, oxoalkoxides, amides or oxoamides are condensed, with elimination of carboxylic acid esters or carboxylic acid amides, until gelation occurs with one or more compounds (II) from the series of metal or semi-metal carboxylates or oxocarboxylates in an anhydrous organic solvent containing no hydroxyl groups. Preferred gels and xerogels contain in the network metal or semi-metal atoms from main group and subgroup III to V and from the rare-earth elements. The gels and xerogels may be used for the production of oxide ceramic materials and for encapsulating pigments.

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