TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Process: The steps (a)-(d), (d1) and (e) optionally further contain at least one gas. The step (a) uses one or more tin containing precursor compound or preparation. The gas is an inert gas. The process uses an auxiliary gas, preferably argon. In the step (b), one or more tin-containing precursor compound or preparation, preferably tin(IV) bromide is obtained. The step (b) contains precursor compounds or preparations of tin and least one halo atom per unit formula. The step (b) is carried out at a temperature of greater than or less than 600 degrees C. The step (c) is carried out at a temperature of greater than or less than 100 degrees C. In the step (c), antimony-containing compound or preparation, or fluorine-containing compound or preparation, is used. In step (c), elementary antimony, metal fluoride or semimetal fluoride is used. The step (d) is carried out at 500-1500 degrees C, preferably greater than 900 degrees C. Tin(IV) oxide is substituted with antimony or fluorine. The step (d1) uses one or more metal- or semimetal containing precursor compound or preparation, preferably titanium(IV) chloride or silicon(IV) chloride. The step (d) forms a titanium(IV)oxide. Preferred Components: The tin-containing precursor compound comprises tin and at least one halo atom per unit formula, preferably tin(IV)bromide, tin(IV) chloride or tin(IV) iodide. Tin(IV)-oxide particles contain different atoms and/or ions. The core is formed from chlorosiloxane-particle (according to EP 03024279.6, T. Giesenberg, S. Hein, M. Binnewies, G. Kickelbick, Angew. Chem. 2004, 116, 5816 or Angew. Chem. Int. Ed. 2004, 43, 5697) (CSN particle).    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The steps (b)-(d), (d1) and (e) are carried out in a hot wall reactor (7) or a hot wall flow tube reactor, where the steps (d) and (e) are carried out in hot wall reactor. The flow tube is made of ceramic or glass. EXAMPLE - No suitable example given.