http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
805 nm Mediated Upconversion Luminescence Properties of Yb3Ga5O12:Ln (Er3+/Nd3+) Nanoparticles
Ayse Dulda 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.9
This paper presents the near infrared and visible upconversion of Yb3Ga5O12 garnet samples. The samples were doped with two different dopants (either Er3+ or Nd3+) and excited with 805 nm. Intense infrared emission was observed with the Nd3+ doped sample and relatively weak visible blue-green and red emissions were observed for both the Er3+ and Nd3+ doped samples. The infrared emission intensities for the Nd3+ doped sample was found to increase with the increase in the Nd3+ ion concentration while that of the Er3+ ion decreases with the increasing Er3+ ion concentration. Also, to ascertain the back energy transfer from the Yb3+ ion to Nd3+, the samples were excited with a 980 nm source. No visible or infrared emission was observed for the Nd3+ doped sample indicating the absence of the back energy transfer. The luminescence properties of the sample signifies its readiness for application in biological imaging and laser generators.
Photoluminescence and morphology of flux grown BAM phosphor using a novel synthesis method
A. Dulda,조덕수,W. J. Park,마사키타카키,윤대호 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.6
Small Eu2+ doped barium magnesium aluminate (BAM : Eu) phosphor particles with a narrow size distribution were prepared using a flux-assisted liquid phase precursor (LPP) method. XRD showed that the crystallinity of BAM particles increased significantly with an increase in the boric acid concentration, as a flux, and the firing temperature. According to FESEM, the phosphor particles produced without the flux and fired at 1450℃ had a rod type morphology, 60-100 nm in diameter and 500- 700 nm in length. The morphology of the phosphor particles transformed from a rod to a hexagonal type with a concomitant increase in the particle size (from ~1 to 2 μm) when 1, 2 and 5 wt% of boric acid was added. The photoluminescence intensity of phosphor particles was also influenced by the addition of the flux due to the enhanced particle size, crystallinity and activator ion distribution.
A. Dulda,M. K. Jung,박우정,마사키타카키,윤대호 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.1
Blue emitting Eu2+ doped barium-magnesium aluminate (BAM) nano-phosphors were synthesized using liquid phase precursor (LPP) method corresponding to Ba0.87-0.90Mg0.91-1.0Al10O17-17.05: Eu0.05. The phosphor particle size, morphology and crystallinity were characterized by FESEM and X-Ray diffraction analysis. The effects of composition and particle size on the luminescence efficiency were investigated by employing photoluminescence spectroscopy. The rod shaped phosphor particles ~60 nm in diameter and 400-700 nm in length were obtained. The phosphor particles emission peaks shifted towards a longer wavelength with 80% luminescence intensity compared with the commercial BAM.
MILLING EFFECT AND ENHANCED LUMINESCENCE PROPERTY OF BAM NANOPHOSPHOR VIA SURFACE MODIFICATIONS
A. DULDA,조덕수,M. TAKAKI,D. H. YOON 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2009 NANO Vol.4 No.6
Surface modification of luminescent nanomaterials has attracted considerable technological interest. With decreasing particle size, the passivation of surface defects is of vital importance. This paper reports the effect of an alkali (KOH) solution treatment and organic functional groups on the luminescence efficiency and particle dispersibility. Fourier transform infrared spectroscopy provided clear evidence of surface modification with organic functional groups from the C=O, C–H, and C–O stretching modes at 1740, 1365, and 1218 cm-1. The KOH-treated sample showed a 40% increase in luminescence intensity, whereas 87% increase in luminescence intensity was obtained from the dispersion-agent-containing sample. To the best of our knowledge, this is the highest efficiency improvement for sub-micrometer-sized BAM:Eu2+ phosphors reported thus far.
Influence of modeling agents on the surface properties of an esthetic nano-hybrid composite
Kutuk, Zeynep Bilge,Erden, Ecem,Aksahin, Damla Lara,Durak, Zeynep Elif,Dulda, Alp Can The Korean Academy of Conservative Dentistry 2020 Restorative Dentistry & Endodontics Vol.45 No.1
Objective: The aim of this study was to evaluate the influence of different modeling agents on the surface microhardness (Vickers hardness number; VHN), roughness (Ra), and color change (ΔE) of a nano-hybrid composite with or without exposure to discoloration by coffee. Materials and Methods: Sixty-four cylinder-shaped nano-hybrid composite specimens were prepared using a Teflon mold. The specimens' surfaces were prepared according to the following groups: group 1, no modeling agent; group 2, Modeling Liquid; group 3, a universal adhesive (G-Premio Bond); and group 4, the first step of a 2-step self-adhesive system (OptiBond XTR). Specimens were randomly allocated into 2 groups (n = 8) according to the storage medium (distilled water or coffee). VHN, Ra, and ΔE were measured at 24 hours, 1 week, and 6 weeks. The Kruskal-Wallis test followed by the Bonferroni correction for pairwise comparisons was used for statistical analysis (α = 0.05). Results: Storage time did not influence the VHN of the nano-hybrid composite in any group (p > 0.05). OptiBond XTR Primer application affected the VHN negatively in all investigated storage medium and time conditions (p < 0.05). Modeling Liquid application yielded improved Ra values for the specimens stored in coffee at each time point (p < 0.05). Modeling Liquid application was associated with the lowest ΔE values in all investigated storage medium and time conditions (p < 0.05). Conclusion: Different types of modeling agents could affect the surface properties and discoloration of nano-hybrid composites.
윤대호,M. K. Jung,W. J. Park,J. W. Moon,마사키타카키,A. Dulda 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5
(Yx,Gdy)O3:Eu3+1-x-y red phosphor was prepared at ring temperatures from 700 ℃ to 1400 ℃ by using liquid phase precursor methods. The particle sizes of the samples prepared at firing temperatures of 800 ℃ and 1000 ℃ were about 23 nm and 64 nm, respectively. The strongest absorption band of the samples excited at 613 nm was observed at 260 nm, which resulted from transitions toward the charge transfer state (CTS) corresponding to the `Eu3+-O2-, interactions. At intense emission peak was observed at 613 nm due to the electric dipole transition of `5D0-7F2' induced by the lack of inversion symmetry at the Eu3+ sites. We observed that the maximum emission intensity of the samples was about 82.3 % at 1400 ℃.
Influence of modeling agents on the surface properties of an esthetic nano-hybrid composite
Kutuk Zeynep Bilge,Erden Ecem,Aksahin Damla Lara,Durak Zeynep Elif,Dulda Alp Can 대한치과보존학회 2020 Restorative Dentistry & Endodontics Vol.45 No.2
Objective: The aim of this study was to evaluate the influence of different modeling agents on the surface microhardness (Vickers hardness number; VHN), roughness (Ra), and color change (ΔE) of a nano-hybrid composite with or without exposure to discoloration by coffee. Materials and Methods: Sixty-four cylinder-shaped nano-hybrid composite specimens were prepared using a Teflon mold. The specimens' surfaces were prepared according to the following groups: group 1, no modeling agent; group 2, Modeling Liquid; group 3, a universal adhesive (G-Premio Bond); and group 4, the first step of a 2-step self-adhesive system (OptiBond XTR). Specimens were randomly allocated into 2 groups (n = 8) according to the storage medium (distilled water or coffee). VHN, Ra, and ΔE were measured at 24 hours, 1 week, and 6 weeks. The Kruskal-Wallis test followed by the Bonferroni correction for pairwise comparisons was used for statistical analysis (α = 0.05). Results: Storage time did not influence the VHN of the nano-hybrid composite in any group (p > 0.05). OptiBond XTR Primer application affected the VHN negatively in all investigated storage medium and time conditions (p < 0.05). Modeling Liquid application yielded improved Ra values for the specimens stored in coffee at each time point (p < 0.05). Modeling Liquid application was associated with the lowest ΔE values in all investigated storage medium and time conditions (p < 0.05). Conclusion: Different types of modeling agents could affect the surface properties and discoloration of nano-hybrid composites.