Nanosized Gd2O3:Eu3+ red phosphor is prepared using a template method from metal salt impregnated into a crystalline cellulose and is dispersed using a bead mill wet process. The driving force of the surface coating between Gd2O3:Eu3+ and mica is induced by the Coulomb force. The red phosphor nanosol is effectively coated on mica flakes by the electrostatic interaction between positively charged Gd2O3:Eu3+ and negatively charged mica above pH 6. To prepare Gd2O3:Eu3+-coated mica (Gd2O3:Eu/mica), the coating conditions are optimized, including the stirring temperature, pH, calcination temperature, and coating amount (wt%) of Gd2O3:Eu3+. In spite of the low luminescence of the Gd2O3:Eu/mica, the luminescent property is recovered after calcination above 600℃ and is enhanced by increasing the Gd2O3:Eu3+ coating amount. The Gd2O3:Eu/mica is characterized using X-ray diffraction, field emission scanning electron microscopy, zeta potential measurements, and fluorescence spectrometer analysis.

Gd2O3:Eu3+ red phosphors were prepared by template method from crystalline cellulose impregnated by metal salt. The crystallite size and photoluminescence(PL) property of Gd2O3:Eu3+ red phosphors were controlled by varying the calcination temperature and Eu3+ mol ratio. The nano dispersion of Gd2O3:Eu3+ was also conducted with a bead mill wet process. Dependent on the time of bead milling, Gd2O3:Eu3+ nanosol of around 100 nm (median particle size : D50) was produced. As the bead milling process proceeded, the luminescent efficiency decreased due to the low crystallinity of the Gd2O3:Eu3+ nanoparticles. In spite of the low PL property of Gd2O3:Eu3+ nanosol, it was observed that the photoluminescent property was recovered after re-calcination. In addition, in the dispersed nanosol treated at 85 oC, a self assembly phenomenon between particles appeared, and the particles changed from spherical to rod-shaped. These results indicate that particle growth occurs due to mutual assembly of Gd(OH)3 particles, which is the hydration of Gd2O3 particles, in aqueous solvent at 85 oC.

Nanosized and aggregated Y2O3:Eu Red phosphors were prepared by template method from metal salt impregnated into crystalline cellulose. The particle size and photoluminescent property of Y2O3:Eu red phosphors were controlled by variation of the calcination temperature and time. Dispersed nanosol was also obtained from the aggregated Y2O3:Eu Red phosphor under bead mill wet process. The dispersion property of the Y2O3:Eu nanosol was optimized by controlling the bead size, bead content ratio and milling time. The median particle size (D50) of Y2O3:Eu nanosol was found to be around 100 nm, and to be below 90 nm after centrifuging. In spite of the low photoluminescent properties of Y2O3:Eu nanosol, it was observed that the photoluminescent property recovered after re-calcination. The dispersion and photoluminescent properties of Y2O3:Eu nanosol were investigated using a particle size analyzer, FE-SEM, and a fluorescence spectrometer.

Fe2O3 coated plate mica(Fe2O3/mica) for infrared reflectance red pigment was prepared under hydrothermal treatment. Fe2O3 was perfectly coated on mica via the difference of surface charge between Fe2O3 and mica particles at pH 3. Fe2O3/mica was then calcined at 800 oC to stabilize the coated layer on mica. The infrare (IR) reflectance pigments were characterized by X-ray diffraction, FE-SEM, zeta potential, and a UV-Vis-NIR spectrophotometer. In particular, the CIE color coordinate and IR reflectance properties of Fe2O3/mica pigments were investigated in relation to the thickness variation of the Fe2O3 layer coated on mica of various lateral sizes. The isolation-heat red paints containing the pigments were prepared and optimized with a thinner, settling agent, and dispersant. Then, the films were made. The thermal property of isolation-heat on these films was observed through the relationship of the IR reflectance value, which was based on the variation of the Fe2O3 layer’s thickness coated on mica and mica’s lateral size as IR reflectance pigment. With an increase in IR reflectance on these films, the thermal property of isolation-heat was effectively enhanced.

Fe4[Fe(CN)6]3 coated on a mica or TiO2/mica surface as infrared reflective blue pigment was prepared by a hydrothermal method. Fe4[Fe(CN)6]3, used as coloring agent, was uniformly coated on mica or TiO2/mica under the optimized condition of a 1.2 : 1 weight ratio between iron(III) chloride hexahydrate and potassium ferrocyanidetrihydrate at the initial pH level of 4.5 at 70˚C. The infrared (IR)-reflective pigments were characterized by SEM, Zeta-potenial, FT-IR, and UV-VIS NIR spectrophotometry. Especially the CIE color coordinate and total solar reflectance(TSR) properties of the pigments were investigated in relation to variation of the coating and coated substrate thicknesses. Isolation-heat paint was prepared with 20 wt% blue pigments fully dispersed in acryl-urethane resin and several additives to coat the film uniformly. The films were also measured with CIE color coordinate, TSR, and the surface temperature was recorded by an isolation-heat measuring system. The pigments and films of Fe4[Fe(CN)6]3 coated on mica and TiO2/mica showed high TSR values compared with the TSR value of Fe4[Fe(CN)6]3 itself. According to the increase of TSR value, the property of isolation-heat is effective. To realize the optimal blue color, we applied the the pigment to TiO2 coated mica(TM(b)) which has blueish interference color. The pigment of Fe4[Fe(CN)6]3 coated on TM(b) shows a strong blue color compared with that of Fe4[Fe(CN)6]3 coated on TiO2/Mmca(TM(w)), which has a whitish interference color.