| 摘要 |
<p>Spherical particles of 5nm-10 mu m contain stannic oxide (SnO2) and optionally at least one further oxide of a main group 1-5 element and/or a transition metal (optionally containing organic groups). The surface of the particles is modified by organic groups, and the SnO2 content of the particles is 0.1-99.9 (preferably 10-90) wt.%. Also claimed are preparation methods of the particles, as follows: (1) forming one or more shells of metal oxide (or metal oxide mixtures) on spherical metal oxide particles, by partial or complete hydrolytic condensation of one or more compounds of M' (and/or their pre-condensates), optionally in presence of catalyst and/or solvent, by the action of water or moisture: (2) hydrolytic condensation of a mixture of tin compounds and at least one compound of M' (or a pre-condensate) as in (1); or (3) emulsifying an aqueous phase containing at least tin in the form of a precipitatable dissolved oxide (hydrate) or sol in an organic phase, using an emulsifier, precipitating SnO2 hydrate or other oxide (hydrate) in the water droplets (before, during or after emulsification) using a solution of ammonium, phosphonium or other onium compound or long-chain organic acid salt (already in the OH or H form or formed in situ) and removing the water by distillation. M' = silicon, boron, aluminium, phosphorus, tin, lead, transition metals, lanthanides and actinides</p> |
