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.

본 논문은 녹색을 발광하는 가넷 형광체 (Lu1-xGdx)3(Al1-yGay)5O12:Ce3+에 관하여 연구하였다. 모든 시편은 입방구조를 가진다. x 증가에 따라 x = 0.20 일 때 559 nm의 peak에서 x = 0.40 일 때 576 nm의 peak로 발광 스펙트럼의 적색편이가 일어나고, x = 0 일 때와 비교하면 x = 0.40 일 때 휘도가 24 %정도 감소한다. 그리고 광여기스펙트럼 또한 유사한 적색편이를 보여준다. y 증가에 따라 y = 0.20 일 때 534 nm의 peak에서 y = 0.40 일 때 524 nm의 peak로 발광 스펙트럼의 청색편이가 일어나고, y = 0 일 때와 비교하면 y = 0.40 일 때 휘도가 46 %정도 감소한다. 그리고 광여기스펙트럼 또한 유사한 청색편이를 보여준다. 본 논문의 가넷 형광체 (Lu1-xGdx)3(Al1-yGay)5O12:Ce3+는 우수한 녹색과 노란색의 색채조정 능력으로 백색발광소자의 색변환 형광체로써 적용될 수 있다.

[ Zn2(1-x)MnxSiO4 ]0.07≤x≤0.15) green phosphor was prepared by solid state reaction. The first heating was at 900˚C-1250˚C in air for 3 hours and the second heating was at 900˚C in N2/H2(95%/5%) for 2 hours. The size effect of SiO2 in forming Zn2SiO4 was investigated. The temperature for obtaining single phase Zn2SiO4 was lowered from 1100˚C to 1000˚C by decreasing the SiO2 particle size from micro size to submicro size. The effect of the activators for the Photoluminescence (PL) intensity of Zn2SiO4:Mn2+ was also investigated. The PL intensity properties of the phosphors were investigated under vacuum ultraviolet excitation (147 nm). The emission spectrum peak was between 520 nm and 530 nm, which was involved in green emission area. MnCl2·4H2O, the activator source, was more effective in providing high emission intensity than MnCO3. The optimum conditions for the best optical properties of Zn2SiO4:Mn2+ were at x = 0.11 and 1100˚C. In these conditions, the phosphor particle shape was well dispersed spherical and its size was 200 nm.

We have synthesized bluish-green, highly-efficient BaSi2O2N2:Eu2+ and (Ba,Sr)Si2O2N2:Eu2+ phosphors through aconventional solid state reaction method using metal carbonate, Si3N4, and Eu2O3 as raw materials. The X-ray diffraction (XRD)pattern of these phosphors revealed that a BaSi2O2N2 single phase was obtained. The excitation and emission spectra showedtypical broadband excitation and emission resulting from the 5d to 4f transition of Eu2+. These phosphors absorb blue light ataround 450nm and emit bluish-green luminescence, with a peak wavelength at around 495 nm. From the results of anexperiment involving Eu concentration quenching, the relative PL intensity was reduced dramatically for Eu=0.033. A smallsubstitution of Sr in place of Ba increased the relative emission intensity of the phosphor. We prepared several white LEDsthrough a combination of BaSi2O2N2:Eu2+, YAG:Ce3+, and silicone resin with a blue InGaN-based LED. In the case of onlythe YAG:Ce3+-converted LED, the color rendering index was 73.4 and the efficiency was 127lm/W. In contrast, in theYAG:Ce3+ and BaSi2O2N2:Eu2+-converted LED, two distinct emission bands from InGaN (450nm) and the two phosphors (475-750nm) are observed, and combine to give a spectrum that appears white to the naked eye. The range of the color renderingindex and the efficiency were 79.7-81.2 and 117-128 lm/W, respectively. The increased values of the color rendering indexindicate that the two phosphor-converted LEDs have improved bluish-green emission compared to the YAG:Ce-converted LED.As such, the BaSi2O2N2:Eu2+ phosphor is applicable to white high-rendered LEDs for solid state lighting.

Green-emitting Ba1.468Sr0.5SiO4 : Eu0.012, Y0.02 phosphor powders under long-wavelength ultraviolet light were prepared via high-temperature flame spray pyrolysis from spray solutions with and without NH4Cl flux. The effects of the temperature of the diffusion flame and the NH4Cl flux on the morphologies, crystal structures and photoluminescence intensities of the Ba1.468Sr0.5SiO4 : Eu0.012, Y0.02 phosphor powders were investigated. The phosphor powders obtained from the spray solution with the NH4Cl flux had higher photoluminescence intensities compared to phosphor powders obtained from the spray solution without the flux. The photoluminescence intensity of the phosphor powders obtained from the spray solution without the flux decreased as the flow rate of the fuel gas increased. On the other hand, the photoluminescence intensity of the phosphor powders obtained from the spray solution with the flux increased as the flow rate of the fuel gas increased. The difference of in the phase purity and morphology of the powders affected the photoluminescence intensities of the phosphor powders.

PDP용 녹색 형광체의 발광특성을 개선시키기 위해 고안된 액상의 화학적 합성법을 사용하여 조성식이 Zn2-x SiO4:xMn(x=0.05, 0.08)인 형광체를 입자크기가 0.5~2μm로 조절하여 제조하였다. 제조된 형광체 입자는 구상이며 잘 분산된 형상을 봉주었고, 고상반응법에 비해 상대적으로 낮은 1080˚C에서 willemite구조의 단일상을 얻을 수 있었다. 또한 진공 자외선 영역의 147 nm의 여기원을 사용하여 광발광 특성을 조사하였다. 입자의 크기가 1μm이고 Mn의 도핑양이 8mole%일 때, 상용 형광체와 비교하여 발광세기는 약 40% 향상되었고 색좌표는 x=0.24, y=0.69로 거의 일치하는 결과를 얻을 수 있었다. 측정된 형광체의 잔광시간은 7.8ms이었다.