• Title/Summary/Keyword: Thulium

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Effect of rare earth dopants on the radiation shielding properties of barium tellurite glasses

  • Vani, P.;Vinitha, G.;Sayyed, M.I.;AlShammari, Maha M.;Manikandan, N.
    • Nuclear Engineering and Technology
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    • v.53 no.12
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    • pp.4106-4113
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    • 2021

  • Rare earth doped barium tellurite glasses were synthesised and explored for their radiation shielding applications. All the samples showed good thermal stability with values varying between 101 ℃ and 135 ℃ based on dopants. Structural properties showed the dominance of matrix elements compared to rare earth dopants in forming the bridging and non-bridging atoms in the network. Bandgap values varied between 3.30 and 4.05 eV which was found to be monotonic with respective rare earth dopants indicating their modification effect in the network. Various radiation shielding parameters like linear attenuation coefficient, mean free path and half value layer were calculated and each showed the effect of doping. For all samples, LAC values decreased with increase in energy and is attributed to photoelectric mechanism. Thulium doped glasses showed the highest value of 1.18 cm-1 at 0.245 MeV for 2 mol.% doping, which decreased in the order of erbium, holmium and the base barium tellurite glass, while half value layer and mean free paths showed an opposite trend with least value for 2 mol.% thulium indicating that thulium doped samples are better attenuators compared to undoped and other rare earth doped samples. Studies indicate an increased level of thulium doping in barium tellurite glasses can lead to efficient shielding materials for high energy radiation.

  • https://doi.org/10.1016/j.net.2021.06.009 인용 PDF KSCI

Theoretical modeling and analysis of thulium doped fluoride fiber amplifier at 1.47 $\mu\textrm{m}$ band amplification (툴륨이 첨가된 플루오르 계열의 광섬유 증폭기의 1.47$\mu\textrm{m}$ 증폭 대역에 대한 모델링과 분석에 대한 연구)

  • 이원재;민범기;박재형;박남규
    • Korean Journal of Optics and Photonics
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    • v.11 no.3
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    • pp.171-178
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    • 2000

  • We present a numerical model which enables to analyze $1.47mu$m amplification band characteristics for thulium doped fluoride fiber amplifiers. We focused on upconversion pumping scheme, thus many transitions affecting $1.47mu$m band amplification was considered simultaneously. Backward propagating waves and transverse mode were also considered in the model. The parameters for modeling were then acquired using published experimental data and related theories such as Judd-Ofelt theory for radiative transition, empirical energy gap law for non-radiative transition, and McCumber relations for cross-sections. The simulation showed well-matched results with experiment and internal dynamics. amics.

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Effect of Thulium Doping on Luminescence Properties of $YAIO_3$and $YTa_7O_{19}$

  • Hojin Ryu;Park, Hee-Dong
    • The Korean Journal of Ceramics
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    • v.3 no.1
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    • pp.43-46
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    • 1997

  • Thulium (Tm) has been incorporated into $YAlO_3$ and $YTa_7O_{19}$ host materials to obtain blue phosphors. $Tm^{3+}$-doped $YAlO_3$ and $YTa_7O_{19}$ phosphors were prepared by the conventional solid state reaction method. According to the results of excitation and emission spectra measured at room temperature, the blue emission intensity of $Tm^{3+}$-doped $YTa_7O_{19}$, peaking at 455 nm was much higher than that of $Tm^{3+}-doped\; YAlO_34, peaking at 458 nm. The maximum of relative intensity of $Tm^{3+}-doped\; YAlO_3\; and\; YTa_7O_{19}$ was obtained at the doping concentration of 0.016 and 0.120 mol% $Tm^{3+}$, respectively. These emission spectra revealed the concentration quenching effect.

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Effects of Dysprosium and Thulium addition on microstructure and electric properties of co-doped $BaTiO_3$ for MLCCs

  • Kim, Do-Wan;Kim, Jin-Seong;Noh, Tai-Min;Kang, Do-Won;Kim, Jeong-Wook;Lee, Hee-Soo
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2010.05a
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    • pp.48.2-48.2
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    • 2010

  • The effect of additives as rare-earth in dielectric materials has been studied to meet the development trend in electronics on the miniaturization with increasing the capacitance of MLCCs (multi-layered ceramic capacitors). It was reported that the addition of rare-earth oxides in dielectrics would contribute to enhance dielectric properties and high temperature stability. Especially, dysprosium and thulium are well known to the representative elements functioned as selective substitution in barium titanate with perovskite structure. The effects of these additives on microstructure and electric properties were studied. The 0.8 mol% Dy doped $BaTiO_3$ and the 1.0 mol% Tm doped $BaTiO_3$ had the highest electric properties as optimized composition, respectively. According to the increase of rare-earth contents, the growth of abnormal grains was suppressed and pyrochlore phase was formed in more than solubility limits. Furthermore, the effect of two rare-earth elements co-doped $BaTiO_3$ on the dielectric properties and insulation resistance was investigated with different concentration. The dielectric specimens with $BaTiO_3-Dy_2O_3-Tm2O_3$ system were prepared by design of experiment for improving the electric properties and sintered at $1320^{\circ}C$ for 2h in a reducing atmosphere. The dielectric properties were evaluated from -55 to $125^{\circ}C$ (at $1KHz{\pm}10%$ and $1.0{\pm}0.2V$) and the insulation resistance was examined at 16V for 2 min. The morphology and crystallinity of the specimens were determined by microstructural and phase analysis.

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