YAG phosphor powders were fabricated by the atmospheric plasma spraying method with the spray-dried spherical YAG precursor. The YAG precursor slurry for the spray drying process was prepared by the PVA solution chemical processing utilizing a domestic easy-sintered aluminum oxide (Al2O3) powder as a seed. The homogenous and viscous slurry resulted in dense granules, not hollow or porous particles. The synthesized phosphor powders demonstrated a stable YAG phase, and excellent fluorescence properties of approximately 115% compared with commercial YAG:Ce3+ powder. The microstructure of the phosphor powder had a perfect spherical shape and an average particle s ize of a pprox imately 30 μm. As a r esult of t he PKG t est of t he YAG p hosphor p owder, t he s ynthesized phosphor powders exhibited an outstanding luminous intensity, and a peak wavelength was observed at 531 nm.

Currently, yellow phosphor of Y3Al5O12:Ce3+ (YAG:Ce) fluorescent material is applied to a 450~480nm blue LED light source to implement a white LED device and it has a simple structure, can obtain sufficient luminance, and is economical. However, in this method, in terms of spectrum analysis, it is difficult to mass-produce white LEDs having the same color coordinates due to color separation cause by the wide wavelength gap between blue and yellow band. There is a disadvantage that it is difficult to control optical properties such as color stability and color rendering. In addition, this method does not emit purple light in the range of 380 to 420nm, so it is white without purple color that can not implement the spectrum of the entire visible light spectrum as like sunlight. Because of this, it is difficult to implement a color rendering index(CRI) of 90 or higher, and natural light characteristics such as sunlight can not be expected. For this, need for a method of implementing sunlight with one LED by using a method of combining phosphors with one light source, rather than a method of combining red, blue, and yellow LEDs. Using this method, the characteristics of an artificial sunlight LED device with a spectrum similar to that of sunlight were demonstrated by implementing LED devices of various color temperatures with high color rendering by injecting phosphors into a 405nm deep blue LED light source. In order to find the spectrum closest to sunlight, different combinations of phosphors were repeatedly fabricated and tested. In addition, reliability and mass productivity were verified through temperature and humidity tests and ink penetration tests.

Burr occurs at the bottom of the material as the material breaks during shearing, and sliver occurs in shear droop that occurs when a punch penetrates the surface of the material. Sliver refers to the shape of a long and thin thread, and it is an important defect that can cause a short when assembled into electronic parts other than a defect in the appearance of a product, an assembly defect in the post-process, and an injury to the operator. Sliver does not occur when the molding is completed only by the main shearing without pre-shearing, but sliver occurs when the main shearing is performed after the pre-shearing. The purpose of this study is to study the sliver generation mechanism that occurs during main shearing after pre-shearing. Using the material phosphor bronze C5210-EH(HP), the sliver was observed with the dimensions and stripping force of the pre-shearing as variables, and the effect of the pre-shearing on the sliver was studied. The product used in the experiment is a terminal, a press product that is assembled on a 0.4mm pitch FPC connector. Three experimental variables were selected: the X-axis allowance, the Y-axis length, and the stripping force in the dimensions of the pre-shearing. As a result of 12 experimental conditions, the X-axis allowance had a greater effect on sliver generation than the Y-axis length and stripping force. The cause of sliver during pre-shearing is that the shear droop part is elongated due to bending when the punch is lowered due to the hole in the bottom due to pre-shearing.

A Y6-xCa1.5xSi11N20O:Ce3+(x=2.5) oxynitride phosphor is synthesized at 1,750 oC in a mixed gas atmosphere of 5% H2 and 95 % N2 by using YN, Ca3N2, Si3N4, and CeO2 as raw material reagents. The crystal structure is a trigonal crystal system that has a P31c (no.159) space group and has lattice parameters of a, b = 9.8876(3), and c = 10.6806(4). This structure is an Er6Si11N20O structure type in which a Y6-xCa1.5xSi11N20O structure is formed by substituting a trivalent Y3+ element and a bivalent Ca2+ element at the position of Er element having an oxidation number of +3. Here, the charge difference caused by different oxidation numbers is balanced by the occupancy of a partially vacant 2c site and an O/N anion ratio in the Er6Si11N20O structure type. The Y6-xCa1.5xSi11N20O:Ce3+ (x = 2.5) phosphor is yellow powder with yellow luminescence; performing Rietveld refinement on the phosphor on the basis of the data obtained by XRD measurement results in the lattice parameters as described above. The Y6-xCa1.5xSi11N20O:Ce3+ (x = 2.5) phosphor has a broad emission band due to Ce3+ as an activator with the center wavelength of 565 nm. This phosphor has a broader emission band than a YAG:Ce3+ phosphor, which is a representative LED phosphor, and thus extends further into the blue and red spectrum ranges. Accordingly, this phosphor is an interesting phosphor that can be used for 1pc-LED with an improved color rendering index.

The co-doping effect of aliovalent metal ions such as Mg2+, Ca2+, Sr2+, Ba2+, and Zn2+ on the photoluminescence of the Y2O3:Eu3+ red phosphor, prepared by spray pyrolysis, is analyzed. Mg2+ metal doping is found to be helpful for enhancing the luminescence of Y2O3:Eu3+. When comparing the luminescence intensity at the optimum doping level of each Mg2+ ion, the emission enhancement shows the order of Zn2+ Ba2+ > Ca2+ > Sr3+> Mg2+. The highest emission occurs when doping approximately 1.3% Zn2+, which is approximately 127% of the luminescence intensity of pure Y2O3:Eu3+. The highest emission was about 127% of the luminescence intensity of pure Y2O3:Eu3+ when doping about 1.3% Zn2+. It is determined that the reason (Y, M)2O3:Eu3+ has improved luminescence compared to that of Y2O3:Eu3+ is because the crystallinity of the matrix is improved and the non-luminous defects are reduced, even though local lattice strain is formed by the doping of aliovalent metal. Further improvement of the luminescence is achieved while reducing the particle size by using Li2CO3 as a flux with organic additives.

Green BaSi2O2N2:0.02Eu2+ phosphor is synthesized through a two-step solid state reaction method. The first firing is for crystallization, and the second firing is for reduction of Eu3+ into Eu2+ and growth of crystal grains. By thermal analysis, the three-time endothermic reaction is confirmed: pyrolysis reaction of BaCO3 at 900 oC and phase transitions at 1,300 oC and 1,400 oC. By structural analysis, it is confirmed that single phase [BaSi2O2N2] is obtained with Cmcm space group of orthorhombic structure. After the first firing the morphology is rod-like type and, after the second firing, the morphology becomes round. Our phosphor shows a green emission with a peak position of 495 nm and a peak width of 32 nm due to the 4f65d1→4f7 transition of Eu2+ ion. An LED package (chip size 5.6 x 3.0 mm) is fabricated with a mixture of our green BaSi2O2N2, and yellow Y3Al5O12 and red Sr2Si5N8 phosphors. The color rendering index (90) is higher than that of the mixture without our green phosphor (82), which indicates that this is an excellent green candidate for white LEDs with a deluxe color rendering index.

We prepared Y3Al5O12;Ce3+,Pr3+ transparent ceramic phosphor using a solid state reaction method. By XRD pattern analysis and SEM measurement, our phosphors reveal an Ia-3d(230) space group of cubic structure, and the transparent ceramic phosphor has a polycrystal state with some internal cracks and pores. In the Raman scattering measurement with an increasing temperature, lattice vibrations of the transparent ceramic phosphor decrease due to its more perfect crystal structure and symmetry. Thus, low phonon generation is possible at high temperature. Optical properties of the transparent ceramic phosphor have broader excitation spectra due to a large internal reflection. There is a wide emission band from the green to yellow region, and the red color emission between 610 nm and 640 nm is also observed. The red-yellow phosphor optical characteristics enable a high Color Rendering Index (CRI) in combination with blue emitting LED or LD. Due to its good thermal properties of low phonon generation at high temperature and a wide emission range for high CRI characteristics, the transparent ceramic phosphor is shown to be a good candidate for high power solid state white lighting.

Cost-effective functional phosphor nanoparticles are prepared by introducing low-cost SiO2 spheres to rareearth phosphor (YVO4:Eu3+, YVO4:Er3+, and YVO4:Nd3+) shells using a sol-gel synthetic method. These functional nanoparticles are characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and general photoluminescence spectra. The SiO2 sphere occupying the interior of the conventional phosphor is advantageous in significantly reducing the cost of expensive rare-earth phosphor nanoparticles. The sol-gel process facilitates the core–shell structure formation; the rare-earth shell phosphor has strong interactions with chelating agents on the surfaces of SiO2 nanoparticles and thus forms layers of several nanometers in thickness. The photoluminescence wavelength is simply tuned by replacing the active materials of Eu3+, Er3+, and Nd3+. Moreover, the photoluminescent properties of the core–shell nanoparticles can be optimized by manipulating the specific contents of active materials in the phosphors. Our simple approach substitutes low-cost SiO2 for expensive rare-earth-based phosphor materials to realize cost-effective phosphor nanoparticles for various applications.

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.

In the construction of a white LED, the region of the red emission is a very important factor. Red light emitting materials play an important role in improving the color rendering index of commercial lighting. These materials also increase the color gamut of display products. Therefore, the development of novel phosphors with red emission and the study of color tuning are actively underway to improve product quality. In the present study, heuristic algorithms were used to search for phosphors capable of increasing the color rendering index and color gamut. Using a heuristic algorithm, the phosphors that were identified were SrGe4O9:Mn4+ and BaGe4O9:Mn4+. Emission spectra study confirmed that these phosphors emit light in the deep red wavelength region, which can fulfill the requirement for the improvement in color rendering index and color gamut for a white LED.

The discovery of new luminescent materials for use in light-emitting diodes(LEDs) has been of great interest, since LED-based solid state lighting applications are attracting a lot of attention in the energy saving and environmental fields. Recent research trends have centered on the discovery of new luminescent materials rather than on fine changes in well-known luminescent materials. In a sense, the novelty of our study beyond simple modification or improvement of existing phosphors. A good strategy for the discovery of new fluorescent materials is to introduce activators that are appropriate for conventional inorganic compounds, that have well-defined structures in the crystal structure database, but have not been considered as phosphor hosts. Another strategy is to discover new host compounds with structures that cannot be found in any existing databases. We have pursued these two strategies at the same time using composite search technology with particle swarm optimization(PSO). In this study, using PSO, we have tracked down a search space composed of Sr-Al-Si-O-N and have discovered a new phosphor structure with yellow luminescence; this material is a potential candidate for UV-LED applications

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.

적색 K2SiF6:Mn4+ 형광체는 SiO2 in/HF/KMnO4H2O solution 용액의 산화환원 반응에 의해 합성된다. 이 형광체 는 450 nm 이하의 파장에서 여기되어 Mn4+의 2Eg → 4A2g에 의해 반치폭이 10 nm인 약 634 nm의 적색 빛을 발광한다. 입자의 크기는 약 5 ㎛이고 결정구조는 Fm-3m (225)의 공간군을 가지는 입방정계이다 (JCPDS85-1382). 온도의존 발광 스펙트럼에서는 약 175 ℃에서의 발광강도가 상온에서보다 66 %까지 감소하였다. 이 형광체는 청색 발광을 하는 InGaN LED에 의해 효과적으로 여기 될 수 있어서 녹색이나 황색 형광체와 함께 사용하여 연색지수가 높은 백색 LED를 만들 수 있다.

Dy3+ and Eu3+-codoped SrWO4 phosphor thin films were deposited on sapphire substrates by radio frequency magnetron sputtering by changing the growth and thermal annealing temperatures. The results show that the structural and optical properties of the phosphor thin films depended on the growth and thermal annealing temperatures. All the phosphor thin films, irrespective of the growth or the thermal annealing temperatures, exhibited tetragonal structures with a dominant (112) diffraction peak. The thin films deposited at a growth temperature of 100 oC and a thermal annealing temperature of 650 oC showed average transmittances of 87.5% and 88.4% in the wavelength range of 500-1100 nm and band gap energy values of 4.00 and 4.20 eV, respectively. The excitation spectra of the phosphor thin films showed a broad charge transfer band that peaked at 234 nm, which is in the range of 200-270 nm. The emission spectra under ultraviolet excitation at 234 nm showed an intense emission peak at 572 nm and several weaker bands at 479, 612, 660, and 758 nm. These results suggest that the SrWO4: Dy3+, Eu3+ thin films can be used as white light emitting materials suitable for applications in display and solid-state lighting.

본 연구의 목적은 광전환재의 사이즈가 다른 광전환 필름을 피복한 온실에서, 실내 생육 환경, 토마토 및 상추의 생육과 품질을 분석하는 것이다. 10μm 이상의 광 전환재를 이용한 광전환 필름(Micro 필름), 500nm 이하의 광전환재를 이용한 광전환 필름(Nano 필름)과 폴리에틸렌(PE) 필름을 2중 온실의 외피복재로 피복하였다. 내피복재는 0.06mm PE 필름을 사용하였고, 내피복 재 및 외피복재의 두께는 모두 0.06mm로 동일하였다. 광전환 필름의 인장강도, 인열강도, 신장율은 PE 필름과 유사하였다. 투광률은 Nano 필름이 600-750nm 및 전체 투광률에서 PE 필름보다 높았으며, Micro 필름은 PE 필름보다 전체 투광률이 낮았다. 온실 내 기온은 Micro 및 Nano 필름 온실이 PE 필름 온실에 비하여 약 2oC정도 높았고, 광전환 필름 온실 간의 유의적인 차이는 없었다. 지온은 Nano 필름 온실이 Micro 필름과 PE 온실에 비하여 각각 1.5, 3 정도 높았다. 토마토의 수량은 PE 필름 온실에 비해 Micro 및 Nano 필름 온실에서 각각 12%, 14% 정도 유의적으로 증가하였고, 당도 차이는 없었다. 그리고 광전환 필름 간의 유의적인 차이는 없었다. 상추의 수량은 Micro 필름 온실이 Nano 필름 및 PE 필름 온실에 비하여 각각 27%, 59% 높았다. Hunter의 적색 값a는 Nano 필름 온실에서 가장 높았다. 토마토와 같이 높은 광을 요구하는 작물은 투광률이 좋은 Nano 필름이 적합하였고, 상추와 같이 낮은 광을 요구하는 작물은 상추는 Micro 필름이 적합하다고 판단되었다.

Eu2+ 이온이 도핑된 질화물 형광체 Sr2Si5N8:Eu2+는 탄소열 환원 질화법 (Carbothermal Reduction Nitridation, CRN)을 이용하여 제조된다. X-선 회절분석기를 이용하여 구조를 관찰할 수 있다. 흡수 밴드 피크인 470 nm 는 Photoluminescence Exitation (PLE) 측정을 통해 확인할 수 있다. 이러한 여기 광은 InGaN 기반으로 한 발광다이오 드에 적용시키기에 효과적일 것으로 기대되며, (Sr1-xEux)2Si5N8:Eu2+ 형광체는 Eu2+ 이온 도핑 농도에 따라 628 nm 부터 670 nm 까지의 피크 파장을 얻을 수 있다. Eu2+의 농도가 증가할수록 발광 파장이 길어지는 적색 편이 현상을 관찰할 수 있다. 청색 발광다이오드에 Y3Al5O12:Ce3+ 형광체와 함께 적용하여 우수한 연색성을 갖는 백색광을 얻을 수 있었다.

The purpose of this study is to improve a process of the automatic manufacturing system for producing a phosphor bronze wire developed the previous study. For this purpose, the authors have improved the manufacturing process, such as wire tension control, discoloration, winding and the control appears as a problem when the automatic manufacturing system applied to the field. Also, performance tests for the developed system such as the straightness, tensile strength, hardness, diameter deviation, discoloration have been performed. As a result, we could product the 0.35mm of phosphor bronze wire with continuous processes. The performance of the prototype system satisfies all the objects of this study.

The purpose of this study is to develop the automatic manufacturing system for producing a phosphor bronze wire. Automatic continuous manufacturing system is necessary to raise the productivity and strengthen the competitiveness in the phosphor bronze wire manufacturing. For this purpose, the authors carrying out the design and production of devices such as raw material supply, drawing, heat treatment, winding and main control system, etc. As a result, we could product the 0.35mm of phosphor bronze wire with continuous processes.

In this study, we fabricated high quality color conversion component with green/red phosphor and low melting glass frit. The color conversion component was prepared by placing the green and red phosphor layer on slide glass via screen printing process. The properties of color conversion component could be controlled by changing coating sequence, layer thickness and heat treatment temperature. We discovered that optical properties of color conversion component were generally determined by the lowest layer. On the other hand, the heat treatment temperature also affected to correlated color temperature (CCT) and color rending index (CRI). The color conversion component with a green (lower) - red (upper) layer which was sintered at 550 oC showed the best optical properties: CCT, CRI and luminance efficacy were 3340 K, 78, and 56.5 lm/w, respectively.