Nitrogen-doped titanium dioxide (N-doped TiO2) is attracting continuously increasing attention as a material for environmental photocatalysis. The N-atoms can occupy both interstitial and substitutional positions in the solid, with some evidence of a preference for interstitial sites. In this study, N-doped TiO2 is prepared by the sol–gel method using NH4OH and NH4Cl as N ion doping agents, and the physical and photocatalytic properties with changes in the synthesis temperature and amount of agent are analyzed. The photocatalytic activities of the N-doped TiO2 samples are evaluated based on the decomposition of methylene blue (MB) under visible-light irradiation. The addition of 5 wt% NH4Cl produces the best physical properties. As per the UV-vis analysis results, the N-doped TiO2 exhibits a higher visible-light activity than the undoped TiO2. The wavelength of the N-doped TiO2 shifts to the visible-light region up to 412 nm. In addition, this sample shows MB removal of approximately 81%, with the whiteness increasing to +97 when the synthesis temperature is 600℃. The coloration and phase structure of the N-doped TiO2 are characterized in detail using UV-vis, CIE Lab color parameter measurements, and powder X-ray diffraction (XRD).

We synthesized potassium hexatitanate, (K2Ti6O13, PT6), with a non-fibrous shape, by acid leaching and subsequent thermal treatment of potassium tetratitanate (K2Ti4O9, PT4), with layered crystal structure. By controlling nucleation and growth of PT4 crystals, we obtained splinter-type crystals of PT6 with increased width and reduced thickness. The optimal holding temperature for the layered PT4 was found to be ~920 oC. The length and width of the PT4 crystals were increased when the nucleation and growth time were increased. After a proton exchange reaction using aqueous 0.3 M HCl solution, and subsequent heat treatment at 850 oC, the PT4 crystal transformed into splinter-type PT6 crystals. The frictional characteristics of the friction materials show that as the particle size of PT6 increases, the coefficient of friction (COF) and wear amounts of both the friction materials and counter disc increase.

Fe-based pigments have attracted much interest owing to their eco-friendliness. In particular, the color of nanosized pigments can be tuned by controlling their size and morphology. This study reports on the effect of length on the coloration of β-FeOOH pigments prepared using an NH4OH solution. First, rod-type β-FeOOH is prepared by the hydrolysis of FeCl3·6H2O and NH4OH. When the amount of NH4OH is increased, the length of the rods decreases. Thus, the length of the nanorods can be adjusted from 10 nm to 300 nm. The color of β-FeOOH changes from orangered to yellow depending on the length of β-FeOOH. The color and phase structure of β-FeOOH is characterized by UVvis spectroscopy, CIE Lab color parameter measurements, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and powder X-ray diffraction (XRD).

This work describes the coloration, chemical stability of SiO2 and SnO2-coated blue CoAl2O4 pigment. The CoAl2O4, raw materials, were synthesized by a co-precipitation method and coated with silica (SiO2) and tin oxide (SnO2) using sol-gel method, respectively. To study phase and coloration of CoAl2O4, we prepared nano sized CoAl2O4 pigments which were coated SiO2 and SnO2 using tetraethylorthosilicate, Na2SiO3 and Na2SiO3 as a coating material. To determine the stability of the coated samples and their colloidal solutions under acidic and basic conditions, colloidal nanoparticle solutions with various pH values were prepared and monitored over time. Blue CoAl2O4 solutions were tuned yellow color under all acidic/basic conditions. On the other hand, the chemical stability of SiO2 and SnO2-coated CoAl2O4 solution were improved when all samples pH values, respectively. Phase stability under acidic/basic condition of the core-shell type CoAl2O4 powders were characterized by transmission electron microscope, X-ray diffraction, CIE L*a*b* color parameter measurements.

Abstract This manuscript reports on compared color evolution about phase transformation of α-FeOOH@SiO₂ and β-FeOOH@SiO2 pigments. Prepared α-FeOOH and β-FeOOH were coated with silica for enhancing thermal properties and coloration of both samples. To study phase and color of α-FeOOH and β-FeOOH, we prepared nano sized iron oxide hydroxide pigments which were coated with SiO2 using tetraethylorthosilicate and cetyltrimethyl-ammonium bro- mide as a surface modifier. The silica-coated both samples were calcined at high temperatures (300, 700 and 1000°C) and characterized by scanning electron microscopy, CIE L*a*b* color parameter measurements, transmission electron microscopy and UV-vis spectroscopy. The yellow α-FeOOH and β-FeOOH was transformed to α-Fe2O3 with red, brown at 300, 700°C, respectively.

This manuscript reports on compared color evolution about phase transformation of α-FeOOH@SiO2 and β-FeOOH@SiO2 pigments. Prepared α-FeOOH and β-FeOOH were coated with silica for enhancing thermal properties and coloration of both samples. To study phase and color of α-FeOOH and β-FeOOH, we prepared nano sized iron oxide hydroxide pigments which were coated with SiO2 using tetraethylorthosilicate and cetyltrimethyl-ammonium bro- mide as a surface modifier. The silica-coated both samples were calcined at high temperatures (300, 700 and 1000°C) and characterized by scanning electron microscopy, CIE L*a*b* color parameter measurements, transmission electron microscopy and UV-vis spectroscopy. The yellow α-FeOOH and β-FeOOH was transformed to α-Fe2O3 with red, brown at 300, 700°C, respectively.

Magnesium hydroxide sulfate hydrate whiskers (, abbreviated 513 MHSH) were prepared using hydrothermal reaction with magnesium oxide (MgO) and magnesium sulfate () as the starting materials. The effects of the molar ratio of /MgO and amount of were studied. As a result, 513 MHSH whiskers co-existed with hexagonal plate at low concentration of . The molar ratio of /MgO was 7:1, uniform 513 MHSH whiskers were formed without impurity such as . Appropriate amount of has affected to formation of high quality MHSH. Their morphologies and structures were determined by powder X-ray diffraction (XRD) scanning electron microscopy (SEM) and thermo-gravimetric analyzer (TGA).

[ ] a cathode material for lithium rechargeable batteries, was prepared using recycled . First, the cobalt hydroxide powders were separated from waste WC-Co hard metal with acid-base chemical treatment, and then the impurities were eliminated by centrifuge method. Subsequently, powders were prepared by thermal treatment of resulting . By adding a certain amount of and , the was obtained by sintering for 10 h in air at . The synthesized particles were characterized by X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) analysis.

Homogenous silica-coated samples with controlled silica thickness were synthesized by the reverse microemulsion method. First, 7 nm size cobalt ferrite nanoparticles were prepared by thermal decomposition methods. Hydrophobic cobalt ferrites were coated with controlled using polyoxyethylene(5)nonylphenylether (Igepal) as a surfactant, and tetraethyl orthosilicate (TEOS). The well controlled thickness of the silica shell was found to depend on the reaction time and the amount of surfactant used during production. Thick shell was prepared by increasing reaction time and small amount of surfactant.

Various inorganic fillers improve the thermal conductivity and physical properties of organic products. Alumina has been used a representative filler in the heat radiation sheet for the heat radiation of electric device. The high filling rate of alumina increases the thermal conductivity and properties of products. We successfully developed the spherical alumina by flame fusion process using the oxygen burner with LPG fuel. In the high temperature flame (25003000) of oxygen burner, sprayed powders were melting and then rotated by carrier gas. This surface melting and rotation process made spherical alumina. Especially effects of chemical composition and particle size of stating materials on the melting behavior of starting materials in the flame and spheroidization ratio were investigated. As a result, spheroidization ratio of boehmite and aluminum hydroxide with endothermic reaction of dehydration process was lower than that of the sintered alumina without dehydration reaction.

Tantalum nitrides () have been developed to substitute the Cd based pigments for non-toxic red pigment. Various doping elements were doped to reduce the amount of high price Tantalum element used and preserve the red color tonality. Doping elements were added in the synthesizing process of precursor of amorphous tantalum oxides and then Tantalum nitrides doped with various elements were obtained by ammonolysis process. The average particle size of final nitrides with secondary phases was larger than the nitride without the secondary phases. Also secondary phases reduced the red color tonality of final products. On the other hand, final nitrides without secondary phase had orthorhombic crystal system and presented good red color. In other words, in the case of nitrides without secondary phases, doping elements made a solid solution of tantalum nitride. In this context, doping process controlled the ionic state of nitrides and the amount of oxygen/nitrogen in final nitrides affected the color tonality.

Aluminum nitride (AlN) powders were prepared by the chemical vapor synthesis (CVS) process in the system. Aluminum chloride () as the starting material was gasified in the heating chamber of . Aluminum chloride gas transported to the furnace in atmosphere at the gas flow rate of 200-400ml/min. For samples synthesized between 700 and , the XRD peaks corresponding to AlN were comparatively sharp and also showed an improvement of crystallinity with increasing the reaction temperature. In additions, the average particle size of the AlN powders decreased from 250 to 40 nm, as the reaction temperature increased.

Colored tantalum oxy-nitride (TaON) and tantalum nitride () were synthesized by ammonolysis. Oxygen deficient tantalum oxides () were produced by a titration process, using a tantalum chloride () precursor. The stirring speed and the amount of were important factors for controling the crystallinity of tantalum oxides. The high crystallinity of tantalum oxides improved the degree of nitridation which was related to the color value. Synthesized powders were characterized by XRD, SEM, TEM and Colorimeter.