title: Synthesis of high concentration colloid solution of silica-coated AgI nanoparticles.
abstract: Methods for high concentration silica-coated silver iodide (AgI/SiO2) particles, which could be practically used as X-ray contrast agent, were examined. The first was a single-step method, which was to prepare AgI nanoparticles at an AgI concentration of 5 x 10(-3) M and coat the AgI nanoparticles with silica shell by a Stöber method. The second was a multiple-step method, which was to repeat a step for preparing a AgI/SiO2 particle colloid solution with 10(-3) M AgI 5 times for adjusting a final AgI concentration to 5 x 10(-3) M. In the two methods, dominant particle aggregation took place, though core-shell particles were also produced. The third was a salting-out method, which was to salt out AgI/SiO2 particles in their colloid solution prepared at an AgI concentration of 10(-3) M, remove supernatant by decantation, and redisperse the particles in a fresh solvent. Consequently, AgI/SiO2 particles with an AgI concentration as high as 0.05 M were successfully prepared with the salting-out method, and their core-shell structure was not damaged during the salting-out.
authors.affiliation: College of Engineering, Ibaraki University, Hitachi, Ibaraki 316-8511, Japan.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Marie
authors.initials: M
authors.lastname: Minato
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Ihara
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Nakagawa
authors.forename: Kohsuke
authors.initials: K
authors.lastname: Gonda
authors.forename: Motohiro
authors.initials: M
authors.lastname: Takeda
authors.forename: Noriaki
authors.initials: N
authors.lastname: Ohuchi
authors.forename: Atsuo
authors.initials: A
authors.lastname: Kasuya