Spherical silica particles with double-layer structures containing silver halides in the core

Silver halides were deposited in the core of the double-layer by the decomp osition of silver complex and trialkoxy (haloalkyl) silanes. The complex, b is[3-(2-aminoethyl) aminopropyl (trimethoxy) silane] silver(I) nitrate, was prepared from silver nitrate and [3-(2-aminoethyl) aminopropyl]trimethoxys ilane in a glove box filled with nitrogen gas and co-hydrolyzed with tetrae thoxysilane. The core particles were prepared by titration of copolymer fro m tetraethoxysilane, the silver complex, 3-bromopropyl (triethoxy) silane a nd chloromethyl (trimethoxy) silane into the mixture of methanol and ammoni a water. Subsequently, the core was coated with the shell formed via titrat ion of tetraethyoxysilane. The resulting particles were larger in diameter than the core particles. The scanning electron micrograph observation has p roved that those particles are spherical and that the particle size distrib ution is narrow. Silver chloride was only deposited in particles when the s ilver complex and chloromethyl (trimethoxy) silane were used as the precurs or. On the other hand, silver bromide was generated when 3-bromopropyl (tri ethoxy) silane or its mixture with chloromethyl (trimethoxy) silane was emp loyed for the formation of silver halide, Deposited silver halides in parti cles were detected on the samples heated up to 700 degreesC by the Xray dif fraction measurement.