Abstract: A colloidal crystal having a diamond lattice structure, including: a first layer in which a first plurality of particles are arranged to form a plane of a face-centered cubic lattice structure; a second layer in which a second plurality of particles are arranged on the first layer in contact with the first particles; and a third layer in which a third plurality of particles are arranged on the second layer in contact with the second particles, wherein the colloidal crystal includes at least one layer of each of the first layer, the second layer and the third layer.

Abstract: [Object] To provide a decorative aqueous composition that includes particles formed from opal-type colloidal crystals uniformly and stably dispersed in an aqueous dispersion medium, and exhibits a structural color due to interference of light, and to provide a method for producing the decorative aqueous composition. [Solution] The decorative aqueous composition of the present invention contains particles of opal-type colloidal crystals dispersed in an aqueous dispersion medium in which a polymer is dissolved. The particles of the opal-type colloidal crystals are made from hydrophilic colloidal particles having an average particle diameter ranging from 10 nm to 1000 nm with a variation coefficient of the particle diameter being within 20%. Therefore, the decorative aqueous composition of the present invention contains opal-type colloidal crystals uniformly and stably dispersed in an aqueous dispersion medium, and exhibits a structural color due to interference of light.

Abstract: [Object] Provided are a “eutectic colloidal crystal” which is an aggregate of plural kinds of colloidal crystals having different lattice constants, a solidified body of the eutectic colloidal crystal, and methods for producing them. [Resolution means] The eutectic colloidal crystal of the present invention contains two or more kinds of colloidal crystals composed of substantially monodispersed colloidal particles having different particle sizes. This eutectic colloidal crystal is obtained by providing a colloidal dispersion of two or more kinds of colloidal particles having different particle sizes, and a polymer which will not substantially adsorb to the colloidal particles (the coefficient of variation in particle size of these colloidal particles is less than 20%) dissolved in a dispersion medium (dispersion preparation process), and allowing the colloidal dispersion to stand (eutectoid process).

Abstract: [Problem] To provide a method for producing a colloidal crystal, wherein the method is easily controlled and is capable of dealing with a wide range of types of colloidal particle. [Solution] The method for producing a colloidal crystal in the present invention is characterized by comprising a preparation step of preparing a colloidal dispersion liquid, in which colloidal particles are dispersed in a liquid comprising an ionic surfactant and a colloidal crystal can be formed due to temperature changes, and a crystallization step of formation of a colloidal crystal by changing the temperature of the colloidal dispersion liquid from a temperature region in which the colloidal crystal is not formed to a temperature region in which the colloidal crystal is formed.

Abstract: [Object] Provided are a “eutectic colloidal crystal” which is an aggregate of plural kinds of colloidal crystals having different lattice constants, a solidified body of the eutectic colloidal crystal, and methods for producing them. [Resolution means] The eutectic colloidal crystal of the present invention contains two or more kinds of colloidal crystals composed of substantially monodispersed colloidal particles having different particle sizes. This eutectic colloidal crystal is obtained by providing a colloidal dispersion of two or more kinds of colloidal particles having different particle sizes, and a polymer which will not substantially adsorb to the colloidal particles (the coefficient of variation in particle size of these colloidal particles is less than 20%) dissolved in a dispersion medium (dispersion preparation process), and allowing the colloidal dispersion to stand (eutectoid process).

Abstract: [Problem] To provide a method for producing a colloidal crystal, wherein the method is easily controlled and is capable of dealing with a wide range of types of colloidal particle. [Solution] The method for producing a colloidal crystal in the present invention is characterized by comprising a preparation step of preparing a colloidal dispersion liquid, in which colloidal particles are dispersed in a liquid comprising an ionic surfactant and a colloidal crystal can be formed due to temperature changes, and a crystallization step of formation of a colloidal crystal by changing the temperature of the colloidal dispersion liquid from a temperature region in which the colloidal crystal is not formed to a temperature region in which the colloidal crystal is formed.