Chang Whan Won

Highly effective synthesis and photoluminescence of Sr2Si5N8:Eu2+ red-emitting phosphor for LEDs.

We developed a highly effective and self-sustaining route for synthesizing Sr(2)Si(5)N(8):Eu(2+) red-emitting phosphor particles for use in light emitting diodes (LEDs). The phosphors thus synthesized showed excellent emission characteristics under a blue excitation wavelength of 450 nm, had a uniform particle size distribution, and showed high performance in LED packages.

Synthesis of ZnS Phosphor Particles in Exothermic Frontal Waves

In this study, temperature profiles and combustion velocities of a Zn + S system in the presence of sodium halide (SH) as an inert diluent were investigated by combining combustion experiments with the thermocouple measurement technique. Flammability limits were determined experimentally by determining the limiting concentrations of sodium halides for which combustion can be initiated and propagated throughout the reaction pellet. The limiting concentration of NaCl was found to be higher than those of NaF and NaI, indicating that NaCl might be a more effective diluent for the Zn + S system. All reaction mixtures were characterized by low combustion temperature in the range 800–1350 °C and burning velocities in the range of 0.024–0.095 cm/s. Depending on the combustion temperature, this synthetic route provides single-phase modified zinc sulfide powders of sphalerite and wurtzite. ZnS samples doped with halogen ions (H–) produced sky-blue emission (470 nm) under 340 nm excitation. ZnS samples codoped with Mn2+ ions showed a red shift (588 nm) under 356 nm excitation. The relative emission intensity of ZnS:Mn2+ phosphor increased as much as 3 times in the NaF → NaI → NaCl range.

Synthesis of Sr 3 Al 2 O 6 Phosphors by Solid State Reaction and Its Luminescent Properties

A red strontium aluminate phosphor (Sr₃Al₂O?:Eu³?, Eu²?) is synthesized using a solid state reaction method in air and reducing atmosphere. The investigation of firing temperature indicates that a single phase of Sr₃Al₂O? is formed when the firing temperature is higher than 1300℃. The effect of firing temperature and doping concentration on luminescent properties are investigated. Sr₃Al₂O? phosphor exhibits the typical red luminescent properties of Eu³? and Eu²?.

SHS in South Korea

SHS processes were introduced in Korea in early 1995. A number of universities and organizations were involved in research activity for the production of various compact and porous inorganic materials. A research group in RASOM carried out fundamental investigations in the field of SHS of 1D, 2D, and 3D nanostructures and LED phosphor powders. Impressive results were achieved in the field of the synthesis of phosphor powders for LED. Based on achievements in the field of the nitride phosphor powders, in 2011 a LED phosphor manufacturing company, Ellim Advanced Materials, Korea, was founded.

Synthesis of BaSrSiO 4 Phosphors by Solid State Reaction and Its Luminescent Properties

Abstract In this study, green barium strontium silicate phosphor (BaSrSiO 4 :Eu 3+ , Eu 2+ ) was synthesized using a solid-statereaction method in air and reducing atmosphere. Investigation of the firing temperature indicates that a single phase of BaSrSiO 4 is formed when the firing temperature is higher than 1400 o C. The effect of firing temperature and doping concentration onluminescent properties are investigated. The light-emitting property was the best when the molar content of Eu 2 O 3 was 0.025mol. Also, the luminescent brightness of the BaSrSiO 4 fluorescent substance was the best when the particle size of the bariumwas 0.5 µ m. BaSrSiO 4 phosphors exhibit the typical green luminescent properties of Eu 3+ and Eu 2+ . The characteristics of thesynthesized BaSrSiO 4 :Eu 3+ , Eu 2+ phosphor were investigated using X-ray diffraction (XRD) and scanning electron microscopy.The maximum emission band of the BaSrSiO 4 :Eu 3+ , Eu 2+ was 520 nm.Key wordsphosphor, BaSrSiO 4 :Eu, solid state reaction.