Seong-Gu Kang

Luminescence Enhancement by Ga3+ Codoping of BaTiO3:Pr3+ Phosphors

The effects of dopant Pr and codopant Ga on the luminescence of BaTiO3 phosphors have been investigated. The maximum luminescence intensity of red emission was observed at a Pr concentration of 0.011 mol %, which is a much lower concentration than those in previous reports on the luminescence characteristics of phosphors. Ga codoping into BaTiO3:Pr3+ phosphors results in a marked increase in luminescence. This result has been interpreted from the viewpoint of symmetry, which makes the occurrence of band-to-band transition probable.

66.3: Emission Characteristics of ZnO-incorporated CaTiO3:Pr3+ Phosphor and its Application for Solid-state Lightings

We have investigated ZnO-incorporated CaTiO3:Pr3+, a red phosphor, and its application for the solid-state lighting. Efficient red emission from the phosphor was obtained by the excitation of wavelength 400 nm. Potentially, ZnO-incorporated CaTiO3:Pr3+ can be used as a complementary phosphor in the red region for the white LEDs.

P‐83: A Novel Red Phosphor for Solid‐state Lighting Applications

We have developed a novel red phosphor based on a layered perovskite structure, Ba(La1−xEux)2Zr3O10. This phosphor showed the red photoluminescence between 580 nm and 630 nm with several excitation bands, which were composed of the charge-transfer band related with the host matrix (around 290 nm) and the 4f 4f transitions of Eu3+ ions (between 350 nm and 460 nm). Since this excitation band is very close to the blue (around 465 nm) or near-UV (around 400 nm) wavelengths of GaN based LED, it is expected to be used as a complementary phosphor in the red region for the white LEDs.

P‐52: Luminescence Properties of Pr‐Doped Perovskite Titanate Phosphors

We presented luminescence properties of various perovskite titanate phosphors like ATiO3:Pr3+ (A = Ca, Sr, Ba, Ca1−xBax, Sr1−xBax). Especially, the effect of Ga addition on the luminescence properties was of our interest. Without the Ga addition, the SrTiO3:Pr3+ and BaTiO3:Pr3+ rarely showed red luminance, while the CaTiO3:Pr3+ phosphor had very intense red luminescence at low concentration of Pr. The Ga addition caused the luminescence enhancement for all of the above perovskite titanate phosphors, especially, the SrTiO3:Pr3+ showed the most outstanding enhancement. Also, we investigated the effects of the change of the A-site in the perovskite phase, ATiO3. While the partial replacement of Ca with Ba led the lumincescence to decrease, the partial substitution of Sr with Ba of 20 mole % led the luminescence to increase about 2 times.

Morphology and Cathodoluminescence of Li-Doped SrTiO 3 :Pr 3+ ,Ga 3+ , A Red Phosphor Operating at Low Voltages

SrTiO 3 :Pr,Ga phosphor using Li 2 CO 3 as a flux has been investigated as a red phosphor for the application to fluorescent displays operated at low voltage. In SrTiO 3 :Pr,Ga system, Pr 3+ can substitute for Sr 2+ because the ionic radius of Pr 3+ almost coincides with that of Sr 2+ . Previous work, it was found by XRF analysis of SrTiO 3 :Pr,Ga single crystal that only a small fraction of Pr ions are incorporated in the SrTiO 3 lattice. In the present study, the effect of Li addition into SrTiO 3 :Pr,Ga on the cathodoluminescence (CL) properties was examined at low acceleration voltage. Especially, thanks to the liquid phase of Li 2 CO 3 during the sintering process, doped Li ions act as a lubricant for the efficient incorporation of Pr ions into SrTiO 3 :Pr,Ga lattice. Furthermore, it is found that the Li addition could enhance the generation of the characteristic emission of Pr-activated SrTiO 3 phosphors.