Research Achievements - Original paper -
-
Scintillation properties of organic–inorganic perovskite-type compounds with fluorophenethylamine
Atsushi Horimoto, Naoki Kawano, Daisuke Nakauchi, Hiromi Kimura, Masaki Akatsuka, Takayuki Yanagida
Optical Materials ( Optical Materials ) 101 2020.03 [Refereed]
Research paper (journal) Domestic Co-author
© 2020 Elsevier B.V. (n-FC6H4C2H4NH3)2PbBr4 {n-FPhe} (n = 2, 3, 4) single crystals were prepared by the poor solvent diffusion method, and their photoluminescence (PL) and scintillation characteristics were evaluated. In PL, a sharp peak due to exciton recombination in the inorganic layer was observed around 400–420 nm in all the samples. Furthermore, they showed a short decay time of 3.4 ns (2-FPhe), 2.7 ns (3-FPhe) and 1.6 ns (4-FPhe) due to the exciton recombination in the inorganic layer under excitation wavelength of 280 nm. In scintillation, they showed a sharp scintillation peak due to excitons recombination in the inorganic layer approximately at 430 nm under X-ray irradiation. The scintillation decay time derived from exciton recombination in the inorganic layer under X-ray irradiation was 5.3 ns (2-FPhe), 6.9 ns (3-FPhe) and 2.8 ns (4-FPhe). Furthermore, the light yield under 241Am gamma-ray irradiation (59.5 keV) was estimated to be 3300 (2-FPhe), 12000 (3-FPhe) and 8300 photons/MeV (4-FPhe).
-
Naoki Kawano, Hiromi Kimura, Daisuke Nakauchi, Kenji Shinozaki, Takayuki Yanagida
Solid State Sciences ( Solid State Sciences ) 100 2020.02 [Refereed]
Research paper (journal) Domestic Co-author
© 2020 Elsevier Masson SAS We evaluated photoluminescence (PL) and scintillation properties of TeO2–Al2O3-WO3 glasses with different concentrations of Nd (0, 0.1, 0.5 and 1.0 mol.%). The glass samples were fabricated by the conventional melt-quenching method. The Nd-doped samples showed sharp emission peaks due to the 4f-4f transitions of Nd3+ in PL and scintillation. The 0.5% and 1.0% Nd-doped samples showed high PL quantum efficiencies and scintillation intensities among the sample tested. Furthermore, the decay time constants for the Nd-doped samples in PL and scintillation were 140–206 and 110–123 μs, respectively. In addition, the undoped and Nd-doped samples showed thermally stimulated luminescence (TSL) with a weak glow peak approximately at 285 °C, and the detection limit of TSL (10 Gy) was much higher than that of common TSL materials.
-
Naoki Kawano, Daisuke Nakauchi, Fumiya Nakamura, Takayuki Yanagida
Journal of the Ceramic Society of Japan ( Journal of the Ceramic Society of Japan ) 128 ( 2 ) 57 - 61 2020.02 [Refereed]
Research paper (journal) Domestic Co-author
© 2020 The Ceramic Society of Japan. All rights reserved. We synthesized a Dy-doped CaF2 translucent ceramic by the spark plasma sintering method, and investigated its scintillation and dosimetric properties compared with those of the single crystal. Both the samples showed sharp peaks across 480670nm due to the 4f4f transitions of Dy3+, and a broad peak approximately at 300nm due to the self-trapped excitons. The decay time constants of both the samples in scintillation were approximately 5 ms, which was close to those for the 4f4f transitions of Dy3+. Regarding thermally-stimulated luminescence, the translucent ceramic exhibited higher sensitivity than the single crystal, and the dynamic range was at least 0.01100 mGy. In addition, both the samples showed optically stimulated luminescence due to the 4f4f transitions of Dy3+ during 590nm stimulation light, but the lowest detection limit of both the samples was approximately 10mGy.
-
Daisuke Nakauchi, Naoki Kawano, Noriaki Kawaguchi, Takayuki Yanagida
Japanese Journal of Applied Physics ( Japanese Journal of Applied Physics ) 59 ( SC ) 2020.02 [Refereed]
Research paper (journal) Domestic Co-author
© 2019 The Japan Society of Applied Physics. (C6H5(CH2)4NH3)2BaxPb1-xBr4 (x = 0, 0.1, 0.25 and 0.5) crystals were prepared by the solvent diffusion method to evaluate the scintillation properties. The samples exhibit photoluminescence and scintillation with a sharp emission peaking around 440 nm due to excitons, and the decay time is dominantly several nanoseconds. The pulse height spectrum under 137Cs gamma-ray irradiation demonstrates that the scintillation light yields of (C6H5(CH2)2NH3)2Ba0.25Pb0.75Br4 and (C6H5(CH2)2NH3)2Ba0.5Pb0.5Br4 crystals are approximately 19 000 ph MeV-1
-
Masaki Akatsuka, Naoki Kawano, Takumi Kato, Daisuke Nakauchi, Go Okada, Noriaki Kawaguchi, Takayuki Yanagida
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment ( Elsevier ) 954 2020.02 [Refereed]
Research paper (journal) Domestic Co-author
© 2018 (C6H5C2H4NH3)2Pb1−xSrxBr4 (x=0.1, 0.25 and 0.5) single crystals were grown by the poor-solvent diffusion method to evaluate their scintillation properties. When X-rays were irradiated upon the sample, the solids demonstrated scintillation with a spectrum of band peaking around 430 nm due to exciton emission from the inorganic layer. The pulse height spectra under 137Cs gamma-rays irradiation were measured by using (C6H5C2H4NH3)2Pb1−xSrxBr4 (x=0.1 and 0.25) crystals, and the estimated scintillation light yields were 19,700 and 18,500 ph/MeV for x=0.1 and 0.25 samples, respectively.
-
Naoki Kawano, Daisuke Nakauchi, Hiromi Kimura, Masaki Akatsuka, Kosuke Takahashi, Fumito Kagaya, Takayuki Yanagida
Japanese Journal of Applied Physics ( Japanese Journal of Applied Physics ) 58 ( 8 ) 2019.07 [Refereed]
Research paper (journal) Domestic Co-author
© 2019 The Japan Society of Applied Physics. We characterized photoluminescence (PL) and scintillation properties of (C6H5C2H4NH3)2Pb1-xMnxBr4 (x = 0.025, 0.05) synthesized by the poor-solvent diffusion method. The Mn-doped samples showed exciton emissions from the inorganic layer approximately at 410 nm while they exhibited an emission approximately at 590 nm due to the 4T1-6A1 transitions of Mn2+ in PL and scintillation. Moreover, the pulse height spectra of the Mn-doped samples were measured under 241Am gamma-ray irradiation (59.5 keV), and the scintillation light yield was estimated to be 1600 (x = 0.025), 1300 (x = 0.05) photons/MeV. In addition, the afterglow level of the Mn-doped samples was found to be 41 ppm (x = 0.025) and 21 ppm (x = 0.05). These afterglow levels were almost equivalent to those of Bi4Ge3O12 and CdWO4, which are famous for low afterglow levels.
-
Naoki Kawano, Hiromi Kimura, Atsushi Horimoto, Kenji Shinozaki, Takayuki Yanagida
Journal of Materials Science: Materials in Electronics ( Journal of Materials Science: Materials in Electronics ) 30 ( 12 ) 11468 - 11474 2019.06 [Refereed]
Research paper (journal) Domestic Co-author
© 2019, Springer Science+Business Media, LLC, part of Springer Nature. We synthesized TeO2-Al2O3-BaO glasses with different concentrations of Eu (0, 0.1, 0.5, 1.0 and 5.0 mol%) by the conventional melt-quenching technique to develop scintillator materials. After the synthesis, photoluminescence (PL) and scintillation properties of the samples were investigated systematically. The Eu-doped samples exhibited emissions with peaks approximately at 590 and 620 nm due to the 4f-4f transitions of Eu3+ in PL and scintillation. Among the sample investigated, the 5.0% Eu-doped sample showed the highest PL and scintillation intensities. In addition, decay time constants of the Eu-doped samples in PL and scintillation were about 0.91–0.94 and 0.37–0.51 ms, respectively. Furthermore, the afterglow levels of the samples were estimated to be 179–245 ppm, which was approximately one order of magnitude higher than those of Bi4Ge3O12 and CdWO4.
-
Photoluminescence, scintillation and TSL properties of Tb-doped strontium aluminoborate glasses
Naoki Kawano, Noriaki Kawaguchi, Go Okada, Yutaka Fujimoto, Takayuki Yanagida
Radiation Measurements 124 69 - 73 2019.05 [Refereed]
Research paper (journal) Domestic Co-author
-
Naoki Kawano, Takumi Kato, Go Okada, Noriaki Kawaguchi, Takayuki Yanagida
Optical Materials ( Optical Materials ) 88 67 - 73 2019.02 [Refereed]
Research paper (journal) Domestic Co-author
© 2018 Elsevier B.V. We synthesized Al2O3 transparent ceramics doped with different concentrations of Eu (0.001, 0.01, 0.1 and 1.0%) by the spark plasma sintering (SPS) method, and then we investigated their photoluminescence (PL), scintillation and thermally-stimulated luminescence (TSL) properties. In the PL, the samples showed a broad emission peak at 400 nm due to the 5d-4f transitions of Eu2+ and several sharp emission peaks across 550–750 nm due to the 4f-4f transitions of Eu3+ and the 3d-3d transitions of Cr3+ impurity ion. In addition to these peaks over 550–750 nm, in scintillation, the samples exhibited two broad peaks over 300–400 nm possibly due to not the 5d-4f transitions of Eu2+ but F and F+ centers. In TSL, the glow curve consisted of peaks at approximately 100, 160, 210 and 320 °C. The TSL intensity of the 0.001% Eu-doped sample was the highest, and the TSL response was confirmed to be linear to irradiated X-ray dose in the range from 0.1 to 1000 mGy.
-
Optical and radiation-induced luminescence properties of Sn-doped magnesium aluminoborate glasses
D. Nakauchi, G. Okada, Y. Fujimoto, N. Kawano, N. Kawaguchi, T. Yanagida
Physics and Chemistry of Glasses: European Journal of Glass Science and Technology Part B 60 ( 1 ) 10 - 14 2019.02 [Refereed]
Research paper (journal) Domestic Co-author
© 2019 Ukrainian State University of Chemical Technology. All rights reserved. We have investigated the optical, radioluminescence and thermoluminescence (TL) properties of Sn-doped magnesium aluminoborate glasses. The glass samples were synthesised by the conventional melt-quenching technique using an alumina crucible under ambient atmosphere. The glass samples exhibit photoluminescence and radioluminescence with a broad emission predominantly due to Sn 2+ , and the decay time constants have typical values for Sn 2+ . The TL glow curves after x-ray irradiation are approximated by a sum of three Gaussian functions at around 130, 180 and 380°C. The TL intensity increases monotonically with irradiated x-ray dose from 1 mGy to 10000 mGy.
-
Thermoluminescence characteristics of Nd-doped LiCaAlF6 single crystal
Noriaki Kawaguchi, Daisuke Nakauchi, Go Okada, Naoki Kawano, Takayuki Yanagida
Journal of Luminescence 206 634 - 638 2019.02 [Refereed]
Research paper (journal) Domestic Co-author
-
Scintillation and photoluminescence properties of Sr<inf>2</inf>CeO<inf>4</inf> ceramics
Takumi Kato, Naoki Kawano, Go Okada, Noriaki Kawaguchi, Masanori Koshimizu, Takayuki Yanagida
Optical Materials ( Elsevier B.V. ) 87 139 - 144 2019.01 [Refereed]
Research paper (journal) Domestic Co-author
© 2018 Elsevier B.V. We have investigated scintillation and photoluminescence (PL) properties of Sr2CeO4 ceramics. The ceramic samples were synthesized by the solid state reaction method sintered at different temperatures (1100, 1200, 1300 and 1400 °C). All the Sr2CeO4 ceramic samples showed PL spectrum with a broad feature peaking around 460 nm. From decay constants of the PL emission, it was confirmed that the origin was due to the charge transfer (CT) transitions of O2—Ce4+ ions. In addition, all the samples showed scintillation induced by X-rays with a spectrum peaking around 500 nm as similarly seen in PL. All of the samples exhibited a clear photoabsorption peak in the pulse height spectra measured under 137Cs γ-ray irradiation, and the absolute scintillation light yield (LY) was the highest for the sample sintered at 1200 °C, and the value was 3200 ph/MeV.
-
Tb<sup>3+</sup>-doped BaF<inf>2</inf>-Al<inf>2</inf>O<inf>3</inf>-B<inf>2</inf>O<inf>3</inf> glass and glass-ceramic for radiation measurements
Go Okada, Kenji Shinozaki, Takayuki Komatsu, Naoki Kawano, Noriaki Kawaguchi, Takayuki Yanagida
Journal of Non-Crystalline Solids 501 111 - 115 2018.12 [Refereed]
Research paper (journal) Domestic Co-author
© 2018 Elsevier B.V. Tb3+-doped BaF2-Al2O3-B2O3 glass and glass-ceramic were synthesized, and the luminescence properties were investigated for potential applications in radiation measurements. The glass-ceramic can be obtained by heat-treating the glass, and it includes BaAlBO3F2 crystalline phase in glass matrix. The photoluminescence (PL) quantum yield is higher for glass than glass-ceramic. The reason can be due to the difference of the number of F− and O2– ions surrounding Tb3+ activator ion. The lifetime of PL is slightly shorter than that of scintillation suggesting energy transfer process from the host to Tb3+ is involved. The time-response of scintillation has significantly slow rise feature possibly due to excited state absorption. Both glass and glass-ceramic show efficient optically-stimulated luminescence (OSL) with equivalent sensitivities despite the large difference of PL efficiency. The latter observation suggests that the glass-ceramic includes large number of OSL active centres than glass. The OSL dynamic range was confirmed to be at least 101–104 mGy.
-
Optical and scintillation properties of 30BaO–(70-x)TiO<inf>2</inf>–xGeO<inf>2</inf> (x = 50, 55, 60) glass-ceramics
Takayuki Yanagida, Hirokazu Masai, Go Okada, Naoki Kawano, Noriaki Kawaguchi
Journal of Non-Crystalline Solids 501 106 - 110 2018.12 [Refereed]
Research paper (journal) Domestic Co-author
© 2017 Elsevier B.V. 30BaO–(70-x)TiO2–xGeO2 (x = 50, 55, 60; BTG) glass and glass-ceramics samples were prepared by a melt-quenching method, and the optical and X-ray induced scintillation properties were investigated. In this study, we prepared twelve different samples: three different compositions (BTGx; x = 50, 55 and 60), two different melting temperatures (1250 and 1550 °C), and with/without crystallization process. The crystallization phenomenon was confirmed by XRD analysis. In photoluminescence spectra, only one broad emission peak at 520 nm was observed in the glass samples, while another peak was observed in glass-ceramic samples at 450 nm in addition to 520 nm peak. The similar tendency was also observed in X-ray induced scintillation spectra. According to the crystallization, the scintillation efficiency was enhanced.
-
Scintillation and dosimeter properties of Ca-doped MgO transparent ceramics
Narumi Kumamoto, Takumi Kato, Naoki Kawano, Go Okada, Noriaki Kawaguchi, Takayuki Yanagida
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms ( Elsevier B.V. ) 435 313 - 317 2018.11 [Refereed]
Research paper (journal) Domestic Co-author
© 2018 Elsevier B.V. We have synthesized 0.001, 0.01 and 0.1% Ca-doped MgO transparent ceramics by the Spark Plasma Sintering (SPS) method, and then we investigated the optical, scintillation and dosimeter properties. In scintillation spectra, some emission bands appeared around 340, 400, 440, 600 and 750 nm. After X-ray irradiation, all the Ca-doped samples showed TSL with a glow peak ∼140 °C, and the 0.01% Ca-doped sample showed an additional broad peak ∼250 °C. The TSL spectrum consists of a broad peak over 300–500 nm and some peaks around 600 and 750 nm. The TSL response was confirmed to linearly increase with irradiation dose over a dose range from 0.1 to 100 mGy.
-
Radiation-induced luminescence centres in Sm:MgF<inf>2</inf> ceramics
Go Okada, Fumiya Nakamura, Naoki Kawano, Noriaki Kawaguchi, Safa Kasap, Takayuki Yanagida
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms 435 268 - 272 2018.11 [Refereed]
Research paper (journal) Domestic Co-author
© 2018 Elsevier B.V. We have prepared Sm:MgF2 ceramics by the spark plasma sintering technique and studied the radio-photoluminescence (RPL) properties. RPL is a phenomenon seen in selected phosphors in which a new photoluminescence (PL) emission centre is generated by ionizing radiations such as X-rays. In the present system, RPL is observed with two different emissions in the blue and near infrared (NIR) ranges due to M(C2h) and M(C1) centres. The dynamic range using the former centre is in the high dose range above 100 Gy while the former centres have a sensitivity below 100 Gy. In addition, heat-treating an irradiated 0.01%Sm:MgF2 sample induces the reduction of the Sm3+-ion, i.e. Sm3+ → Sm2+). These centres are metastable, and their concentration can be increased or decreased by heat-treatment and exposing to UV light.
-
Photoluminescence and scintillation properties of Eu-doped strontium aluminate crystals
Daisuke Nakauchi, Go Okada, Koshimizu Masanori, Naoki Kawano, Noriaki Kawaguchi, Takayuki Yanagida
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms 435 273 - 277 2018.11 [Refereed]
Research paper (journal) Domestic Co-author
© 2018 Elsevier B.V. Eu-doped SrAl12O19, SrAl4O7, Sr4Al14O25 and SrAl2O4 bulk crystals were successfully synthesized by the floating zone method. The samples exhibit photoluminescence and scintillation with an intense broad emission due to the 5d-4f transitions of Eu2+ in the visible range, and Eu:SrAl12O19 shows additional several sharp emissions owing to Eu3+. The Eu2+ emission blue-shifts as the Al-ratio increases. Pulse height spectrum measurements under 137Cs γ-ray irradiation demonstrated a clear photoabsorption peak, in which the scintillation light yields were estimated to be 6,900 (Eu:SrAl12O19), 700 (Eu:SrAl4O7), 6,500 (Eu:Sr4Al14O25) and 42,000 (Eu:SrAl2O4) photons/MeV.
-
Dosimetric properties of Al<inf>2</inf>O<inf>3</inf> transparent ceramics doped with C
Takumi Kato, Naoki Kawano, Go Okada, Noriaki Kawaguchi, Takayuki Yanagida
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms 435 296 - 301 2018.11 [Refereed]
Research paper (journal) Domestic Co-author
© 2017 Elsevier B.V. We have investigated scintillation and thermally-stimulated luminescence (TSL) dosimetric properties of Al2O3 transparent ceramics doped with different concentrations of C ions (0.001, 0.01 and 0.1%). The samples were synthesized by the Spark Plasma Sintering (SPS) technique. All the samples showed scintillation with emission peaks at 310, 410 and 693 nm under X-ray irradiation. Based on the scintillation decay times measured, the origins of emissions at 310, 410 and 693 nm were attributed to F+ centers, F centers and Cr3+ impurity ions, respectively. The samples show notable TSL with a glow curve consisting of peaks at 30, 100, 165, 230, 330 and 405 °C with much higher intensities than those of undoped Al2O3 transparent ceramics. A TSL response was confirmed to be linear to the irradiation dose over a range from 0.1 to 1000 mGy.
-
Scintillation and TSL properties of Tb-doped NaPO<inf>3</inf>-Al(PO<inf>3</inf>)<inf>3</inf> glasses
Naoki Kawano, Masaki Akatsuka, Hiromi Kimura, Go Okada, Noriaki Kawaguchi, Takayuki Yanagida
Radiation Measurements ( Radiation Measurements ) 117 52 - 56 2018.10 [Refereed]
Research paper (journal) Domestic Co-author
© 2018 Elsevier Ltd We synthesized NaPO3-Al(PO3)3 glasses with different concentrations of Tb (0.3, 1.0, 3.0 and 10.0 mol%) by the conventional melt-quenching technique. After the synthesis, their photoluminescence (PL), scintillation and TSL properties were characterized systematically. All the glass samples showed intense PL and scintillation having a spectrum of sharp peaks at around 490, 540, 590 and 620 nm due to the 4f-4f transitions of Tb3+. The intensities of PL and scintillation were the highest for the 10.0% Tb-doped glass among the samples investigated. In thermally-stimulated luminescence (TSL), the intensity was the highest for the 1.0% Tb-doped sample. We also demonstrated dose response of TSL, and the 0.3% and 1.0% Tb-doped samples exhibited a linear response to X-ray dose over a dose range of 10–10000 mGy.
-
Comparative study of scintillation and dosimetric properties between Tm-doped CaF<inf>2</inf> translucent ceramic and single crystal
Naoki Kawano, Daisuke Nakauchi, Kentaro Fukuda, Go Okada, Noriaki Kawaguchi, Takayuki Yanagida
Japanese Journal of Applied Physics 57 ( 10 ) 2018.10 [Refereed]
Research paper (journal) Domestic Co-author
© 2018 The Japan Society of Applied Physics. We fabricated a Tm-doped CaF2 translucent ceramic by spark plasma sintering (SPS), and evaluated its photoluminescence (PL), scintillation, and dosimetric properties compared with those of a single crystal. Both the samples exhibited emission peaks originating from the 4f-4f transitions of Tm3+ under visible-light and X-ray irradiation. The intensities of PL and scintillation for the single crystal were higher than those for the translucent ceramic. Regarding thermally stimulated luminescence (TSL), both the samples showed main glow peaks at approximately 145 and 265 °C. The Tm-doped translucent ceramic exhibited a higher TSL sensitivity than did the single crystal and showed a linear response against X-ray dose over the dose range from 0.01 to 1000 mGy.