Published on Web 02/22/2007
Thermally Driven Unidirectional Crystallization of Charged Colloidal Silica Akiko Toyotama,† Junpei Yamanaka,*,† Masakatsu Yonese,† Tsutomu Sawada,‡ and Fumio Uchida§ Faculty of Pharmaceutical Sciences, Nagoya City UniVersity, 3-1 Tanabe, Mizuho, Nagoya, Aichi 467-8603, Japan, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan, and Fuji Chemical Co., Ltd., 1-35-1 Deyashiki-Nishi, Hirakata, Osaka 573-0003, Japan Received November 17, 2006; E-mail:
[email protected] Charged colloidal particles dispersed in water self-assemble into “crystal” structure, when the electrostatic interparticle interaction is sufficiently strong.1 These colloidal crystals have received considerable attention as photonic crystals since their Bragg wavelengths usually lie in the visible light regime. Thus, ingenious crystallizations2-5 have been developed to date. Here, we report a novel directed crystallization of dilute colloidal silica in coexistence with pyridine (Py), under a temperature gradient. This method enables the fabrication of well-oriented and large (1 mm × 10 mm × ∼30 mm) single-domain crystals in a short time (
