We report the optical properties and morphological structure of potential green phosphors ͑Sr 1−x Ca x Ga 2 S 4 :Eu, x = 0.0-1.0͒ for application in phosphor-converted three-band white light emitting diodes ͑LEDs͒. A series of Sr 1−x Ca x Ga 2 S 4 :Eu phosphors was synthesized using NaBr-aided solid-state reactions in a flowing H 2 S stream. They all crystallized with the orthorhombic PbGa 2 Se 4 phase, and their emissions were efficiently excited up to 480 nm. The optical and morphological suitability of Sr 1−x Ca x Ga 2 S 4 :Eu phosphors is discussed in terms of their application as coatings for altering the color of blue LEDs.

Rice paddy fields have been recognized as an alternative habitat for avian wetland foragers, and fish-rice farms have become a new tool in improving the abundance of aquatic animals. However, the use of the habitats by avian foragers, particularly by oriental storks (Ciconia boyciana), was not well understood. In the present study, we investigated how a fish-rice farm influenced the abundance of aquatic animals and documented the foraging behavior of the two captive bred oriental storks in a closed semi-natural paddy field. Our results showed that the fish refuge pond (water depth 40 cm) had a higher abundance of fish whereas the areas planted with rice (water depth 20 cm) had more tadpoles and some aquatic insects. The two captive bred oriental storks captured mostly fish and aquatic insects in the rice-planted area and mostly fish in the fish refuge pond. The two oriental storks had higher foraging success and spent more time for foraging in the rice-planted area than in the fish refuge pond. This result suggests that the oriental storks might prefer foraging in the area with fish, aquatic insects, and amphibians under a greater success rate presumably due to shallow water depth in the paddy fields with a fish-rice farm.

Europium ion doped strontium thiogallate (SrGa 2 S 4 :Eu) has been considered as an excellent green-emitting phosphor, due to the emission wavelength of 535 nm originated from the 4f 6 5d1 → 4f 7 transition of Eu 2+ ion in SrGa 2 S 4 :Eu. 1,2SrGa 2 S 4 :Eu have been widely used as the green-emitting phosphor for low voltage (≤ 2 kV) and moderate voltage (2-10 kV) field emission displays (FEDs). 3,4 Recently, high luminescent blue light emitting diodes (LED) based on InGaN technology have been developed. 5-7The phosphorconverted white LED using blue LED is considered as one of the most important lightning sources, due to its long lifetime, low energy consumption, and eco-friendly materials, without any mercury. The conventional white LED is fabricated by coating yellow-emitting Y 3 Al 5 O 12 :Ce phosphor onto the blue InGaN LED chip.8-10 White light is produced by the combination of unabsorbed blue emission of the blue InGaN LED chip, and yellow emission of the Y 3 Al 5 O 12 :Ce phosphor. However, the color rendering index of this conventional white LED is very poor. To improve the color rendering index of white LED, a three-band white LED with red, green, and blue emissions must be developed. A threeband white LED can be fabricated by coating a mixture of red-and green-emitting phosphors onto a blue LED chip. 11,12Since SrGa 2 S 4 :Eu has a strong absorption broadband in the 400-500 nm wavelength range, SrGa 2 S 4 :Eu is an appropriate green-emitting phosphor that is excited by the commercial blue InGaN LED chip. SrGa 2 S 4 :Eu has in recent years once again received great attention as a candidate for the greenemitting phosphor for the phosphor-converted three-band white LED.SrGa 2 S 4 :Eu has generally been synthesized by a solidstate reaction of SrCO 3 , Ga 2 O 3 , and Eu 2 O 3 in a flowing toxic hydrogen sulfide (H 2 S) gas.13,14 To eliminate the harmful synthetic conditions, SrGa 2 S 4 :Eu was then prepared by a solid-state reaction of SrS, Ga 2 S 3 , and EuS in 5% H 2 /95% N 2 gas, instead of H 2 S.15 SrGa 2 S 4 :Eu has also been prepared by a solid-state decomposition reaction from SrS, gallium complex [Ga(Me 2 dtc) 3 ], and europium complex [(Me 4 N)-Eu(Me 2 dtc) 4 ] with using inert Ar gas. 16 We have also synthesized SrGa 2 S 4 :Eu by using a similar solid-state decomposition reaction from SrS, Ga(Me 2 dtc) 3 , and (Me 4 N)Eu(Me 2 dtc) 4 , without using any gases.17 In this paper, we present an environmentally safe solid-state reaction for the preparation of SrGa 2 S 4 :Eu phosphor prepared from SrS, Ga 2 S 3 , and (Me 4 N)Eu(Me 2 dtc) 4 , without using any gases. We investigated the optimal synthetic conditions of reaction temperature, reaction time, choice of flux, and amount of Eu 2+ ion as activator, for the brighter green-emitting SrGa 2 S 4 :Eu phosphor. We also compared the photoluminescent properties of SrGa 2 S 4 :Eu phosphors prepared by two kinds of gallium precursors, Ga(Me 2 dtc) 3 and Ga 2 S 3 .Figures 1(a) and 1(b) show the photoluminescence ex-

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Phosphors V 1250Moderate Voltage Cathodoluminescence of Y2O2S:Eu, SrGa2S4:Eu, and ZnS:Ag,Al for CNT-FEDs. -The title phosphors are characterized by powder XRD, SEM, and cathodoluminescence spectroscopy at applied voltages of 3-8 kV. The results indicate that Y2O2S:Eu, SrGa2S4:Eu, and ZnS:Ag,Al are excellent red-, green-, and blue-emitting phosphors for carbon nanotube field emission display applications. -(NA, S.-H.; SUNG, H.-J.; YOU, Y.-C.; KO, K.-Y.; DO, Y. R.; HUH*, Y.-D.; Bull.