Abstract: The invention provides titanium dioxide fine particles, wherein nitrogen and at least one element selected from carbon, hydrogen, sulfur doped in titanium dioxide by heat-treating fine particles of a material of titanium dioxide at 500° C. or more and 600° C. or less in a reducing gas atmosphere containing nitrogen. The titanium fine particles exhibit a high photocatalytic activity than in the conventional art by irradiating a visible light such that they exhibit an isopropanol oxidation activity induced by visible light irradiation with a wavelength of 400 nm or more and 600 nm or less with excellent stability and durability of the photocatalytic activity.

Abstract: The ceramic member of this invention is formed on the surfaces of crystal grains with a plurality of protrusions having smaller diameter than that of the crystal grain, said crystal grain composing at least the surface or its vicinity of a dense ceramic base material of purity being 95 wt % or higher. Such ceramic members may be produced by performing the surface of a dense ceramic base material with a corrosion treatment in an acid etchant, the dense ceramic base material having purity of 95 wt % or higher and exceeding 90% of a theoretical density, whereby ceramic grains existing on the surface or its vicinity of the base material are formed on the surface thereof with a plurality of protrusions.

Abstract: The invention provides titanium dioxide fine particles, wherein nitrogen and at least one element selected from carbon, hydrogen, sulfur doped in titanium dioxide by heat-treating fine particles of a material of titanium dioxide at 500° C. or more and 600° C. or less in a reducing gas atmosphere containing nitrogen. The titanium fine particles exhibit a high photocatalytic activity than in the conventional art by irradiating a visible light such that they exhibit an isopropanol oxidation activity induced by visible light irradiation with a wavelength of 400 nm or more and 600 nm or less with excellent stability and durability of the photocatalytic activity.

Abstract: The ceramic member of this invention is formed on the surfaces of crystal grains with a plurality of protrusions having smaller diameter than that of the crystal grain, said crystal grain composing at least the surface or its vicinity of a dense ceramic base material of purity being 95 wt % or higher. Such ceramic members may be produced by performing the surface of a dense ceramic base material with a corrosion treatment in an acid etchant, the dense ceramic base material having purity of 95 wt % or higher and exceeding 90% of a theoretical density, whereby ceramic grains existing on the surface or its vicinity of the base material are formed on the surface thereof with a plurality of protrusions.

Abstract: A crystalline inorganic fiber or molded body thereof is thermally treated in gas atmosphere containing chlorine. The crystalline inorganic fiber or molded body thereof contains small impurities such as Fe, Cu and Ni. For example, Fe is 15 ppm or less, Cu is 1 ppm or less, and Ni is 0.5 ppm or less.

Abstract: A treatment apparatus for analyzing the impurities in silicic material with high precision, includes a container having an inner space in which at least one analysis sample container and a sample decomposing solution are accommodated. The container is divided into a lid body and a lower body, each of the lid body and the lower body being opened at the division surface side thereof to form an open end and being closed at the surface side opposite to the division surface side to form a close end thereof. The inner peripheral surface of the open end of the lower body is formed in a stepwise shape so that the analysis sample container is disposed to be spaced from the surface of the decomposing solution which is stocked in the lower body, and the inner peripheral surfaces of the lid body and the lower body are smoothly continuously threadily engaged with each other through abutment faces thereof to keep the container in an appropriate hermetic level.