| abstract |
A stable sol which comprises colloidal particles of modified stannic oxide-zirconium oxide composite having a particle size of from 4.5 to 60 nm, said colloidal particles consisting essentially of, as nuclei, colloidal particles of stannic oxide-zirconium oxide composite having a particle size of from 4 to 50 nm and having a structure in which colloidal particles of stannic oxide and colloidal particles of zirconium oxide are bonded to each other in a ratio, by weight of these oxides, of from 0.02 to 1.0 as ZrO₂/SnO₂, and, as a coating on the surface of the nuclei, colloidal particles of tungstic oxide-stannic oxide composite having a particles size of from 2 to 7 nm and a WO₃/SnO₂ weight ratio of from 0.5 to 100, and which has a total content of metal oxides of from 2 to 50 wt%. |