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RISS 인기검색어
- 검색키워드
- 저자 : Meejitpaisan, P. (검색결과 2 건)
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White light emission of dysprosium doped lanthanum calcium phosphate oxide and oxyfluoride glasses
Luewarasirikul, N.,Kim, H.J.,Meejitpaisan, P.,Kaewkhao, J. Elsevier 2017 Optical materials Vol.66 No.-
<P><B>Abstract</B></P> <P>Lanthanum calcium phosphate oxide and oxyfluoride glasses doped with dysprosium oxide were prepared by melt-quenching technique with chemical composition 20La<SUB>2</SUB>O<SUB>3</SUB>:10CaO:69P<SUB>2</SUB>O<SUB>5</SUB>:1Dy<SUB>2</SUB>O<SUB>3</SUB> and 20La<SUB>2</SUB>O<SUB>3</SUB>:10CaF<SUB>2</SUB>:69P<SUB>2</SUB>O<SUB>5</SUB>:1Dy<SUB>2</SUB>O<SUB>3</SUB>. The physical, optical and luminescence properties of the glass samples were studied to evaluate their potential to using as luminescence materials for solid-state lighting applications. The density, molar volume and refractive index of the glass samples were carried out. The optical and luminescence properties were studied by investigating absorption, excitation, and emission spectra of the glass samples. The absorption spectra were investigated in the UV–Vis–NIR region from 300 to 2000 nm. The excitation spectra observed under 574 nm emission wavelength showed the highest peak centered at 349 nm (<SUP>6</SUP>H<SUB>15/2</SUB> → <SUP>6</SUP>P<SUB>7/2</SUB>). The emission spectra, excited with 349 nm excitation wavelength showed two major peaks corresponding to 482 nm blue emission (<SUP>4</SUP>F<SUB>9/2</SUB> → <SUP>6</SUP>H<SUB>15/2</SUB>) and 574 nm yellow emission (<SUP>4</SUP>F<SUB>9/2</SUB> → <SUP>6</SUP>H<SUB>13/2</SUB>). The experimental lifetime were found to be 0.539 and 0.540 for oxide and oxyfluoride glass sample, respectively. The x,y color coordinates under 349 nm excitation wavelength were (0.38, 0.43) for both glass samples, that be plotted in white region of CIE 1931 chromaticity diagram. The CCT values obtained from the glass samples are 4204 K for oxide glass and 4228 K for oxyfluoride glass corresponding to the commercial cool white light (3100–4500 K). Judd-Ofelt theory had also been employed to obtain the J-O parameters (Ω<SUB>2</SUB>, Ω<SUB>4</SUB> and Ω<SUB>6</SUB>), oscillator strength, radiative transition possibility, stimulated emission cross section and branching ratio. The Ω<SUB>2</SUB> > Ω<SUB>4</SUB> > Ω<SUB>6</SUB> trend of J-O parameters of both glass samples may indicate the good quality of a glass host for using as optical device application. Temperature dependence of emission spectra was studied from 300 K to 10 K and found that the intensity of the emission peak was found to be increased with decreasing of the temperature. The results of the investigations in this work confirmed that the present Dy-doped lanthanum calcium phosphate oxide and oxyfluoride glasses perform high potential for using as efficient luminescence materials for solid-state lighting applications, especially for white LEDs. Furthermore, the oxyfluoride glass sample provides more luminescence potential than the oxide glass sample.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Lanthanum calcium phosphate oxide and oxyfluoride glasses doped with Dy<SUP>3+</SUP> were studied. </LI> <LI> Emission spectra showed two major peaks corresponding to 482 and 574 nm. </LI> <LI> Both glasses corresponding to the commercial cool white light (3100–4500 K). </LI> <LI> Judd-Ofelt theory had also been employed to obtain the J-O parameters. </LI> <LI> Oxyfluoride glass provides more luminescence potential than the oxide glass. </LI> </UL> </P>
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Zaman, F.,Rooh, G.,Srisittipokakun, N.,Kim, H.J.,Kaewnuam, E.,Meejitpaisan, P.,Kaewkhao, J. Pergamon 2017 Radiation physics and chemistry Vol.130 No.-
<P>Ce3+ activated Li2O-Gd2O3-BaO-B(2)O(3)glass scintillator containing neutron-capture elements (Li-7, (11)Band Gd-158)were developed by conventional melt-quenching technique. Luminescence spectra under UV and X-ray excitation showed Ce3+ ion emission due to 5d -> 44f transition at 391 nm. Energy transfer from the host glass to Ce(3+)ions were confirmed by VUV-UV and XEL spectra. The highest emission intensity of Ce(3+)ions were observed at 0.5 mol%of CeF3. For the same concentration the decay time was obtained to be 19.7 ns and their mean critical distance was calculated about 22.33 angstrom. The observed decay constants revealed that direct electron-hole capture was a dominant scintillation process in the present glass matrix. (C) 2016 Elsevier Ltd. All rights reserved.</P>
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