mixture comprising 112 g 0 35 mole of tetrabutoxy silane 11 2 g 0 62 mole of water and 62 g of butyl alcohol was admixed with 0 2 ml of hydrochloric acid and agitated at room temperature for 1 week so that about 50 of the alkoxy silane compound was hydrolyzed to form a solution containing the hydroxy silane as the partial hydrolysis product of the tetrabutoxy silane in a concentration of 15 by weight as silica thereafter this solution was diluted by adding butyl alcohol to provide a concentration of the hydroxy silane of 6 2 silica and 168 2 g of the thus diluted solution were admixed with 10 5 g of a 50 by weight solution of tributoxy antimony in butyl alcohol to form an antimony containing solution which served as the coating solution a silicon wafer was coated with this coating solution and then subjected to the diffusion treatment of antimony substantially in the same manner as in example 1 to give an antimony doped silicon wafer which had a surface resistivity of 41 ohm square the spinner used in the coating works with the above described coating solution was absolutely free from corrosion even after repeated service over a long period of time using the same coating solution a mixture comprising 76.