Spherical porous ceramics particles were synthesized by the sol-gel process from tetramethoxysilane (TMOS), methyltrimethoxysilane, zirconyl chloride, zirconium tetrapropoxide and titanium tetraisopropoxide in a W/O emulsion, respectively. The pore size of silica gels could be controlled to within 4 to 600 nm by changing the compositions of polyethyleneglycol (PEG), H
2O and the organic solvent in the starting solutions. The interconnected pore structure of the gels could be made by eliminating PEG from the gel bodies. Spherical silica glass particles with an interconnected pore structure were synthesized from spherical borosilicate particles by successive thermal and acid treatments. The size of the pores could be controlled to within 10 to 50 nm by selecting the temperature and time of the thermal treatment. Zirconia particles were obtained by the addition of urea and hexamethylenetetramine in the starting solution. The peak pore diameter of the particles was 4 nm. The pore volume increased with an increase in the calcium content. After the extraction of calcium by hot water, the specific surface area of the particles was enhanced by 110 m
2/g. SiO
2-ZrO
2 binary particles were synthesized by using zirconium tetrapropoxide and 2-methoxy ethanol. The specific surface area of the particles was 260 m
2/g. After extraction of the SiO
2 parts by a 1 M NaOH aqueous solution, the weight loss of the particle was 10 mass%. Titania particles were obtained by the addition of diethanolamine or 2-methoxy ethanol in the starting solution. The peak pore-diameter of the particles was 4 nm. TiO
2-SiO
2 binary particles were synthesized by using 2-methoxy ethanol. The specific surface area of the particles was 180 m
2/g after extraction of the SiO
2 parts by a 0.1 M NaOH aqueous solution.
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