Energy transfer based emission analysis of Eu³⁺ doped Gd₂O₃-CaO-SiO₂-B₂O₃ glasses for laser and X-rays detection material applications

Wantana, N.,Kaewnuam, E.,Damdee, B.,Kaewjaeng, S.,Kothan, S.,Kim, H.J.,Kaewkhao, J. Elsevier 2018 Journal of luminescence Vol.194 No.-

<P><B>Abstract</B></P> <P>The Eu<SUP>3+</SUP>-doped CaO-Gd<SUB>2</SUB>O<SUB>3</SUB>-SiO<SUB>2</SUB>-B<SUB>2</SUB>O<SUB>3</SUB> glasses were prepared to study photoluminescence, lasing potential and scintillation properties. Glasses absorb photons in ultraviolet, visible light and near infrared regions and are assigned to the energy transitions of Gd<SUP>3+</SUP> and Eu<SUP>3+</SUP>. Ultraviolet with 275nm can generate the strong red emission with 614nm via energy transfer form Gd<SUP>3+</SUP> to Eu<SUP>3+</SUP>. X-ray scintillation study exhibits strong emission pattern due to Gd-Eu energy transfer. The optimum concentrations of Eu<SUP>3+</SUP> ion in this glass is 0.30mol% as it results maximum emission intensity. The fluorescence lifetime of the <SUP>5</SUP>D<SUB>0</SUB> level decreases from 1.763 to 1.726ms when concentration increased from 0.05 to 0.40mol%. From Judd-Ofelt analysis, this glass exhibit high potential for using as laser medium for red laser device with high lasing power and energy extraction ratio. Moreover, this glass performs the integral scintillation efficiency as 13% compared with BGO.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Ce³⁺ doped glass for radiation detection material

Wantana, N.,Kaewnuam, E.,Chanthima, N.,Kaewjaeng, S.,Kim, H.J.,Kaewkhao, J. Elsevier 2018 CERAMICS INTERNATIONAL Vol.44 No.suppl1

<P><B>Abstract</B></P> <P>The Ce<SUP>3+</SUP> doped sodium-gadolinium-aluminum-phosphate glasses, with 20Na<SUB>2</SUB>O− 10Gd<SUB>2</SUB>O<SUB>3</SUB> − 10Al<SUB>2</SUB>O<SUB>3</SUB> − (60-x)P<SUB>2</SUB>O<SUB>5</SUB> − xCeF<SUB>3</SUB> (where x = 0.00, 0.10, 0.50, 1.50, 2.00 and 3.00 mol%) composition, have been measured and analyzed. The prepared glasses were studied various properties such as physical, optical, luminescence and scintillation. The densities of glasses were found to increase with the concentration of CeF<SUB>3</SUB> while molar volumes decreased. The value of absorption edge is shifted from 313 nm of host glass to longer wavelength with CeF<SUB>3</SUB> doping. The indirect and direct band gap decreased with increasing CeF<SUB>3</SUB> content which corresponded to the molar volume reduction representing the enhancement of non-bridging oxygen (NBO) number in glass network. Photoluminescence spectra showed the strong emission bands centered between 325 and 347 nm under Ce<SUP>3+</SUP> directly excitation and Gd<SUP>3+</SUP> excitation. The optimum concentrations of CeF<SUB>3</SUB> concentration in this glass is 2.00 mol% as it resulted the maximum emission intensity. The strongest emission band of x-ray induced optical luminescence is around 375 nm. The integrated scintillation efficiency of 2.0 mol% CeF<SUB>3</SUB> doped glass was 9.6% compared with bismuth germanium oxide (BGO) crystal. The most dominant decay times of 2.0 mol% doped glass was fast as 26.8 ns that performed the rapid response with coming excitation energy. In this work, our developed glasses performed the strong and fast luminescence signal which can be applied as the scintillation material in radiation detector.</P>

Forecasting Government Bond Yields in Thailand: A Bayesian VAR Approach

Wantana BUABAN,Yuthana SETHAPRAMOTE 한국유통과학회 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.3

This paper seeks to investigate major macroeconomic factors and bond yield interactions in Thai bond markets, with the goal of forecasting future bond yields. This study examines the best predictive yields for future bond yields at different maturities of 1-, 3-, 5-, 7-, and 10-years using time series data of economic indicators covering the period from 1998 to 2020. The empirical findings support the hypothesis that macroeconomic factors influence bond yield fluctuations. In terms of forecasting future bond yields, static predictions reveal that in most cases, the BVAR model offers the best predictivity of bond rates at various maturities. Furthermore, the BVAR model has the best performance in dynamic rolling-window, forecasting bond yields with various maturities for 2-, 4-, and 8-quarters. The findings of this study imply that the BVAR model forecasts future yields more accurately and consistently than other competitive models. Our research could help policymakers and investors predict bond yield changes, which could be important in macroeconomic policy development.

The Effect of Roselle (Hibicus sabdariffa Linn.) Calyx as Antioxidant and Acidifier on Growth Performance in Postweaning Pigs

Aphirakchatsakun, Wantana,Angkanaporn, Kris,Kijparkorn, Suwanna Asian Australasian Association of Animal Productio 2008 Animal Bioscience Vol.21 No.4

Two experiments, involving a total of 100 crossbred pigs (Hampshire$\times$Landrace$\times$Duroc) aged 5 weeks, were used to evaluate the effect of Roselle (Hibicus sabdariffa Linn.) calyx as an antioxidant and acidifier on growth performance. Experiment 1: growth performance response of pigs fed basal corn-soy diet was compared with that of pigs consuming diets that contained 4, 8 and 12% Roselle in powder form, 4 g/kg acidifier (Fra$^{(R)}$Acid Dry) or 100 mg/kg antibiotic (Aurofac$^{(R)}$). All diets were isocaloric and isonitrogenous. Twenty-four castrated male and twelve female pigs were randomly allocated into 6 treatments which comprised 3 replicates (2 male and 1 female) of 2 pigs each. The results demonstrated no beneficial weight gain and feed intake response among treatments at 7, 9 and 11 weeks of age (p>0.05). However, feed-to-gain ratios (FCR) of Roselle-fed groups were significantly different from the basal-diet group at 7 weeks of age (p<0.05). Pigs fed with 8% Roselle had the lowest FCR. Therefore, 8% was set as an appropriate level of Roselle in feed. Experiment 2 was conducted to determine antioxidant and acidifier properties. Pigs were fed similar diets to Experiment 1 except that Roselle was fed to only one treatment at the level of 8%. Sixty-four piglets, 32 castrated male and female each were randomly allocated into 4 treatments which comprised 4 replicates (2 male and 2 female) of 4 pigs each. Body weight was measured. At 7 and 9 weeks of age, four pigs from each treatment were randomly selected. The pH in their gastrointestinal tract, pepsin activity in stomach mucosa, trypsin activity in the pancreas and protein and fat digestibility in the ileum were measured to investigate acidifier properties. For antioxidant properties, malondialdehyde (MDA) and glutathione concentration in plasma and liver were used as parameters. The results showed no significant difference in weight gain, pH or pepsin activity among all treatments at both ages (p>0.05). Nevertheless, trypsin activity and fat digestibility of the Roselle-fed group were higher than the basal-diet group at 7 weeks of age (p<0.05). Glutathione in plasma was significantly different between antibiotic-fed and basal-diet groups (p<0.05). Significant differences were found only in some parameters and between the basal-diet group and the other groups. Therefore, it cannot be precisely concluded that Roselle in powder form has clear acidifier and antioxidant properties in postweaning pigs. Further studies should be undertaken to clearly confirm both properties.

Development of lithium yttrium borate glass doped with Dy³⁺ for laser medium, W-LEDs and scintillation materials applications

Kaewnuam, E.,Wantana, N.,Kim, H.J.,Kaewkhao, J. North-Holland 2017 Journal of non-crystalline solids Vol.464 No.-

<P>Lithium yttrium borate glasses doped with dysprosium ion (Dy3+) were synthesized by a melt-quenching technique. Glasses were studied the physical properties such as density, molar volume and refractive index. The absorption, excitation and emission spectra, including decay curve were monitored to study the luminescence properties. The X-ray induced luminescence and temperature dependence luminescence spectra was also investigated. The experimental results show that Dy3+ probably acts as modifier in this glass because molar volume increased with increasing of Dy3+ doped content. Glasses absorbs photon in visible light and near-infrared region with Dy3+ transition from H-6(15/2) ground state. Glass performs the strongest emission at 575 nm (F-4(9/2) -> H-6(13/2)) with 388 nm excitation wavelength. The intensity of emission increases with increasing of Dy2O3 concentration until 1.00 mol% after that it decreases by resonance energy transfer and cross-relaxation processes. The photo emission is white light confirmed by CIE 1931 chromaticity and UV lamp excitation. Decay curve, fitted by Inokutie-Hirayama model (S = 6), shows the non-exponential pattern which indicates a dipole-dipole interaction between Dy3+ donor and acceptor in glass. Judd-Ofelt analysis exhibits an interesting potential for using glass as laser medium with 575 nm emitting. X-ray induced luminescence spectra perform the sharp emission band of Dy3+ after accepted energy transfer from host glass. This is a good sign for scintillation potential. Temperature dependence luminescence spectra show the strong emission at low temperature condition. Emission intensity relates linearly with the temperature change. This Dy3+ doped glass can be developed for using as photonic materials in the display, white-light emitting diode, laser device, scintillation detector and even temperature sensor. (C) 2017 Elsevier B.V. All rights reserved.</P>

Luminescence characteristics of Dy3+ doped Gd2O3-CaO-SiO2-B2O3 scintillating glasses

Kaewkhao, J.,Wantana, N.,Kaewjaeng, S.,Kothan, S.,Kim, H.J. Elsevier 2016 Journal of rare earths Vol.34 No.6

<P>Glasses were prepared from the compositions of 25Gd(2)O(3)-10CaO-10SiO(2)-(55-x)B2O3-xDy(2)O(3) (where x is 0.0 mol.%-1.0 mol.%) by the conventional melt-quenching technique at 1400 degrees C. The results demonstrated the increase in the glass density with respect to the increase in the doping concentrations of Dy2O3. Nine absorption bands were observed. The emission spectra of the developed glass showed two strong peaks at 577 nm (F-4(9/2)-> H-6(13/2)) and 482 nm (F-4(9/2)-> 6H(15/2)). The highest emission intensity was observed from the developed glass prepared at 0.4 mol.% of Dy2O3, as the efficient energy transfer took place from Gd3+ to Dy3+. From the X-ray induced optical luminescence, the emission spectra were identical to those from PL measurements, but with the highest intensity observed from the glass quenched at 0.45 mol.% of Dy2O3. Finally, the integral scintillation efficiency of the developed glass was determined at 27% of that of the commercially available BGO crystal.</P>

Catalytic enhancement of platinum supported on zeolite beta for toluene hydrogenation by addition of palladium

Sirinuch Loiha,Karin Fottinger,Katrin Zorn,Wantana Klysubun,Gunter Rupprechter,Jatuporn Wittayakun 한국공업화학회 2009 Journal of Industrial and Engineering Chemistry Vol.15 No.6

This work focused on the preparation, characterization and catalytic performance of a bimetallic platinum–palladiumcatalyst for toluene hydrogenation. A catalyst with 3 wt% loading of each metal was prepared by co-impregnation on zeolite beta in proton form and denoted as 3Pt3Pd/HBEA. The structure of HBEA was retained after catalyst preparation and the metal occupied strong acidic sites of the zeolite. Compared to monometallic 3Pt/HBEA, the 3Pt3Pd/HBEA exhibited smaller Pt particle size due to better dispersion on the support. The catalytic performance of the bimetallic catalyst at various temperatures indicated that the presence of Pd enhanced toluene hydrogenation of Pt catalyst at high temperature. The most suitable temperature for toluene hydrogenation on 3Pt3Pd/HBEA was 150 8C for which a complete toluene conversion was obtained with methylcyclohexane as the only product.

Characteristics and photocatalytic degradation of methyl orange on Ti-RH-MCM-41 and TiO2/RH-MCM-41

Surachai Artkla,Kitirote Wantala,Bang-orn Srinameb,Nurak Grisdanurak,Wantana Klysubun,Jatuporn Wittayakun 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.6

Our purpose was to synthesize, characterize and test photodegradation of methyl orange on two catalysts containing 10 wt% titanium supported on mesoporous MCM-41 synthesized with rice husk silica. The first catalyst was Ti-RH-MCM-41 prepared by adding tetrabutyl orthotitanate (TBOT) in a synthetic gel of RH-MCM-41, and the second catalyst was TiO2/RH-MCM-41 prepared by grafting TBOT on the preformed RH-MCM-41. The mesoporous structures were observed on both catalysts and they had surface area of 1,073 and 1,006 ㎡/g. The Ti in Ti-RHMCM- 41 was in the form of Ti(IV) with tetrahedral geometry residing in the mesoporous structure. This form was less active for photodegradation of methyl orange than the other one. The Ti in TiO2/RH-MCM-41 was anatase titania with octahedral geometry located outside the mesoporous framework. This form was more an active phase for the photodegradation and the reaction parameters on this catalyst were further investigated. The optimum catalyst weight to methyl orange volume ratio was 5 g/L and the optimum initial concentration of the dye was 2.0 ppm. The degradation rate obeyed pseudo-first order and the adsorption of methyl orange on TiO2/RH-MCM-41 obeyed Langmuir isotherm.

Photoluminescence and white light generation of Dy₂O₃ doped Li₂O-BaO-Gd₂O₃- SiO₂ for white light LED

Khan, I.,Rooh, G.,Rajaramakrishna, R.,Srisittipokakun, N.,Wongdeeying, C.,Kiwsakunkran, N.,Wantana, N.,Kim, H.J.,Kaewkhao, J.,Tuscharoen, S. Elsevier 2019 JOURNAL OF ALLOYS AND COMPOUNDS Vol.774 No.-

<P><B>Abstract</B></P> <P>Dy<SUP>3+</SUP>-doped Li<SUB>2</SUB>O-BaO-Gd<SUB>2</SUB>O<SUB>3</SUB>-SiO<SUB>2</SUB> (LBGS) glasses were prepared by traditional melt quenching techniques and characterized through absorption and emission spectra. Tauc's plot for allowed direct and indirect transition are shown studied and observed in the range of 3.5 (eV) to 2.9 (eV). The variation in the band gap with the addition of Dy<SUB>2</SUB>O<SUB>3</SUB> is due to structural changes in the glass matrix. For 0.5 mol% of Dy<SUP>3+</SUP> ions doped LBGS glasses Judd-Ofelt analysis was carried out further these parameters were used to study their radiative properties for the excited luminescent levels of Dy<SUP>3+</SUP> ions. White light generation was evaluated as a function of the Dy<SUP>3+</SUP> ions concentration by measuring yellow-to-blue emission intensity ratios and CIE chromaticity coordinates. The non-exponential decay were observed for glasses doped beyond 0.1 mol% and were well fitted to IH-model for S = 6 (dipole-dipole interaction). The non-exponential behavior and life time quenching have been accredited to the energy transfer through dipole-dipole interaction among the excited and unexcited Dy<SUP>3+</SUP>ions. Pulse X-Ray decay time has measured for 0.5 mol% of Dy<SUP>3+</SUP> ions doped LBGS glass. CIE-1931 chromaticity coordinates and decay profile analysis were studied. The correlated color temperature (CCT) for LBGS-0.5Dy is found to be 3621 K at λ<SUB>exc</SUB> = 350 nm. The quantum efficiency (η) for the title LBGS-0.5Dy glass is found to be 74%. The highest values for radiative transition probability (A<SUB>R</SUB>), emission cross section (σ(λ<SUB>P</SUB>)), experimental and calculated branching ratio (β<SUB>R</SUB>) have been observed for <SUP>4</SUP>F<SUB>9/2</SUB> → <SUP>6</SUP>H<SUB>13/2</SUB> at 576 nm.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Oscillator strength and Judd-Ofelt (Ω<SUB>2</SUB>) parameter in the present glass is high. </LI> <LI> Tauc's plot for allowed direct and indirect transition were studied for LBGS glasses. </LI> <LI> The bonding parameter for LBGS-0.5Dy glass indicates the ionic nature of Dy<SUP>3+</SUP> ions. </LI> <LI> Yellow to blue (Y/B) ratio increase upto 0.5 mol% of Dy<SUB>2</SUB>O<SUB>3</SUB> and then start decreasing. </LI> <LI> The decay time are found to be decreasing with increase in dopant concentration. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Emission spectrum of LBGS-Dy glasses measured at room temperature.</P> <P>[DISPLAY OMISSION]</P>

Influence of Er³⁺ ion concentration on optical and photoluminescence properties of Er³⁺-doped gadolinium-calcium silica borate glasses

Kesavulu, C.R.,Kim, H.J.,Lee, S.W.,Kaewkhao, J.,Wantana, N.,Kothan, S.,Kaewjaeng, S. Elsevier Sequoia 2016 JOURNAL OF ALLOYS AND COMPOUNDS Vol.683 No.-

The Er<SUP>3+</SUP>-doped gadolinium calcium silica borate glasses of composition (55-x) B<SUB>2</SUB>O<SUB>3</SUB> - 10 SiO<SUB>2</SUB> - 25 Gd<SUB>2</SUB>O<SUB>3</SUB> - 10 CaO - x Er<SUB>2</SUB>O<SUB>3</SUB>, where x = 0.0, 0.5, 1.0, 1.5, 2.0 and 2.5 mol %, have been prepared by conventional melt quenching technique and are characterized through optical absorption, visible and near-infrared (NIR) emission spectra and decay time measurements. Judd-Ofelt (JO) intensity parameters (Ω<SUB>λ</SUB>, λ = 2, 4 and 6) have been derived from the absorption spectrum of 0.5 mol % Er<SUB>2</SUB>O<SUB>3</SUB> doped glass and in turn are used to calculate radiative properties for the important luminescent levels of Er<SUP>3+</SUP> ions. The studied glasses show intense and broad green (550 nm) and red (591 nm) visible emissions under at 379 nm excitation. Upon excitation at 980 nm laser diode, an intense 1.53 μm NIR emission has been observed with the maximum full width at half maximum (FWHM) and its value is found to be 106 nm for 2.5 mol % Er<SUP>3+</SUP>-doped gadolinium calcium silica borate glasses. This broad luminescence locates in the region of 1420-1635 nm and covers the S, C and L bands. The decay curves of the <SUP>4</SUP>I<SUB>13/2</SUB> level exhibit exponential nature for all the concentrations. The lifetime of the <SUP>4</SUP>I<SUB>13/2</SUB> level has found to be decrease from 1.46 to 1.35 ms with increase of Er<SUP>3+</SUP> ion concentration. Hence, these results clearly indicate that present glasses are suitable for efficient short and conventional-length optical amplifiers and tunable lasers.