• Title/Summary/Keyword: sub-100 nm

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Properties of Green-Emitting CaNb2O6:Tb3+ Thin Films Grown by Radio-Frequency Magnetron Sputtering (라디오파 마그네트론 스퍼터링으로 성장한 녹색 발광 CaNb2O6:Tb3+ 박막의 특성)

  • Seonkyeong Kim;Shinho Cho
    • Korean Journal of Materials Research
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    • v.33 no.10
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    • pp.400-405
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    • 2023
  • Tb3+-doped CaNb2O6 (CaNb2O6:Tb3+) thin films were deposited on quartz substrates at a growth temperature of 300 ℃ using radio-frequency magnetron sputtering. The deposited thin films were annealed at several annealing temperatures for 20 min and characterized for their structural, morphological, and luminescent properties. The experimental results showed that the annealing temperature had a significant effect on the properties of the CaNb2O6:Tb3+ thin films. The crystalline structure of the as-grown CaNb2O6:Tb3+ thin films transformed from amorphous to crystalline after annealing at temperatures greater than or equal to 700 ℃. The emission spectra of the thin films under excitation at 251 nm exhibited a dominant emission band at 546 nm arising from the 5D47F5 magnetic dipole transition of Tb3+ and three weak emission bands at 489, 586, and 620 nm, respectively. The intensity of the 5D47F5 (546 nm) magnetic dipole transition was greater than that of the 5D47F6 (489 nm) electrical dipole transition, indicating that the Tb3+ ions in the host crystal were located at sites with inversion symmetry. The average transmittance at wavelengths of 370~1,100 nm decreased from 86.8 % at 700 ℃ to 80.5 % at an annealing temperature of 1,000 ℃, and a red shift was observed in the bandgap energy with increasing annealing temperature. These results suggest that the annealing temperature plays a crucial role in developing green light-emitting CaNb2O6:Tb3+ thin films for application in electroluminescent displays.

Optical Properties of Ga2O3 Single Crystal by Floating Zone Method (부유대역법을 이용한 단결정Ga2O3의 광학적 특성)

  • Gim, JinGi;Kim, Jongsu;Kim, Gwangchul
    • Journal of the Semiconductor & Display Technology
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    • v.20 no.4
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    • pp.78-82
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    • 2021
  • The Ga2O3 single crystal was grown through a floating zone method, and its structural and optical properties were instigated. It has a monoclinic crystal structure with a (100) crystal orientation and an optical band gap energy of 4.6 eV. It showed an average transmittance of 70% in the visible region. At room temperature, its photoluminescent spectrum showed three different peaks: the ultraviolet at 360 nm, the blue-green at 500 nm, and the red peaks at 700 nm. Especially, at liquid nitrogen temperature, the ultraviolet peak was optically active while the others were quenched.

Transition Metal Oxide Multi-Layer Color Glass for Building Integrated Photovoltaic System (BIPV 시스템을 위한 전이금속 산화물 다중층 컬러 유리 구현 기술 연구)

  • Ahn, Hyeon-Sik;Gasonoo, Akpeko;Jang, Eun-Jeong;Kim, Min-Hoi;Lee, Jae-Hyun;Choi, Yoonseuk
    • Journal of IKEEE
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    • v.23 no.4
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    • pp.1128-1133
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    • 2019
  • This paper proposed colored front panel glass for Building Integrated Photovoltaic (BIPV) systems using multi-layered thin films composed of transition metal oxide (TMO) layers. Molybdenum oxide (MoO3) and tungsten oxide (WO3) provided complementary and suitable materials in making effective interference of reflected light from interfaces with significant difference in refractive indices. A simple, fast, and cheap fabrication method was achieved by depositing the multi-layer films in a single thermal evaporator. Magenta colored glass with optical transmittance of more than 90% was achieved with MoO3 (60nm)/WO3(100nm) multi-layered film. This technology could play in a critical role in commercial BIPV system applications.

Ultraviolet-emissive BaSiO3:Ce3+ Phosphor for VUV Excimer Lamp

  • Lee, Jugyeong;Afandi, Mohammad M.;Kim, Jongsu;Heo, Hoon
    • Journal of the Semiconductor & Display Technology
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    • v.20 no.2
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    • pp.1-5
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    • 2021
  • Ultraviolet (UVA)-emissive BaSiO3:Ce3+ phosphor was astonishingly reproducible by vacuum-sintering at a high temperature through a simple solid-state reaction method. It was conveniently formed in BaSiO3 phases. The compound showed the UVA emission and the UV-VUV excitation due to 5d-4f transitions from Ce3+ ions: emission peak at 380 nm with a 56 nm width. Its temperature dependence and vacuum UV excitability were examined for practical application as an excimer discharge lamp, which showed the high thermal stability (80% at 100℃) and the strong VUV excitations at 145 nm and 172 nm.

Influences of the Eu Concentration and the Milling Time on Photoluminescence Properties of Y2O3-H3BO3:Eu3+ Powders Prepared by Mechanical Alloying

  • Gong, Hyun-Sic;Kim, Hyun-Goo
    • Journal of Powder Materials
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    • v.23 no.2
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    • pp.108-111
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    • 2016
  • $Y_2O_3-H_3BO_3:Eu^{3+}$ powders are synthesized using a mechanical alloying method, and their photoluminescence (PL) properties are investigated through luminescence spectrophotometry. For samples milled for 300 min, some $Y_2O_3$ peaks ([222], [440], and [622]) and amorphous formations are observed. The 300-min-milled mixture annealed at $800^{\circ}C$ for 1 h with Eu = 8 mol% has the strongest PL intensity at every temperature increase of $100^{\circ}C$ (increasing from 700 to $1200^{\circ}C$ in $100^{\circ}C$ increments). PL peaks of the powder mixture, as excited by a xenon discharge lamp (20 kW) at 240 nm, are detected at approximately 592 nm (orange light, $^5D_o{\rightarrow}^7F_1$), 613 nm, 628 nm (red light, $^5D_o{\rightarrow}^7F_2$), and 650 nm. The PL intensity of powder mixtures milled for 120 min is generally lower than that of powder mixtures milled for 300 min under the same conditions. PL peaks due to $YBO_3$ and $Y_2O_3$ are observed for 300-min-milled $Y_2O_3-H_3BO_3$ with Eu = 8 mol% after annealing at $800^{\circ}C$ for 1 h.

Effect of Deposition Temperature on the Optical Properties of La2MoO6:Dy3+,Eu3+ Phosphor Thin Films (증착 온도에 따른 La2MoO6:Dy3+,Eu3+ 형광체 박막의 광학 특성)

  • Cho, Shinho
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.32 no.5
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    • pp.387-392
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    • 2019
  • $Dy^{3+}$ and $Eu^{3+}$-co-doped $La_2MoO_6$ phosphor thin films were deposited on sapphire substrates by radio-frequency magnetron sputtering at various growth temperatures. The phosphor thin films were characterized using X-ray diffraction (XRD), scanning electron microscopy, ultraviolet-visible spectroscopy, and fluorescence spectrometry. The optical transmittance, absorbance, bandgap, and photoluminescence intensity of the $La_2MoO_6$ phosphor thin films were found to depend on the growth temperature. The XRD patterns demonstrated that all the phosphor thin films, irrespective of growth temperatures, had a tetragonal structure. The phosphor thin film deposited at a growth temperature of $100^{\circ}C$ indicated an average transmittance of 85.3% in the 400~1,100 nm wavelength range and a bandgap energy of 4.31 eV. As the growth temperature increased, the bandgap energy gradually decreased. The emission spectra under ultraviolet excitation at 268 nm exhibited an intense red emission line at 616 nm and a weak emission line at 699 nm due to the $^5D_0{\rightarrow}^7F_2$ and $^5D_0{\rightarrow}^7F_4$ transitions of the $Eu^{3+}$ ions, respectively, and also featured a yellow emission band at 573 nm, resulting from the $^4F_{9/2}{\rightarrow}^6H_{13/2}$ transition of the $Dy^{3+}$ ions. The results suggest that $La_2MoO_6$ phosphor thin films can be used as light-emitting layers for inorganic thin film electroluminescent devices.

Synthesis of 100 nm BaTiO3 by Solid-state Reaction (고상법에 의한 100 nm BaTiO3 분말의 합성)

  • Kim, Jung-Hwan;Jung, Han-Seong;Cho, Joon-Yeob;Hong, Jeong-Oh;Kim, Young-Tae;Hur, Kang-Heon
    • Journal of the Korean Ceramic Society
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    • v.46 no.2
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    • pp.170-174
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    • 2009
  • $BaTiO_3$ powder was synthesized by the solid-state reaction of fine $BaTiO_3$ and $TiO_2$ raw materials. Fine grinding media of 50 and 300 microns were used for obtaining fine particulate mixture of $BaTiO_3$ and $TiO_2$ with high homogeneity. Effect of the size of grinding media on the synthesis mechanism of $BaTiO_3$ was discussed on the basis of the particulate morphology and thermogravimetry data for the mixture powders. By using the finer grinding media, $BaTiO_3$ was formed at the lower temperature and the particle size with the relatively narrower distribution could be obtained. $BaTiO_3$ powder with the average size of 100 nm was synthesized by the solid reaction in vacuum atmosphere.

Effect of Pulse Plating on Hardness of Brass-Alumina Nanocomposite (펄스전류인가가 황동-알루미나 나노복합도금층의 경도에 미치는 영향)

  • 오영주;안재우;안종관;이만승
    • Journal of the Korean institute of surface engineering
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    • v.35 no.3
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    • pp.158-164
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    • 2002
  • Nanocomposites consisting of a nanocrystalline brass matrix (grain size ; 20-100nm) with sub-micron sized Al2O3 particles (60-200nm) were prepared by pulsed current electrodeposition. The microhardness of the nanocomposite with a grain size of 90-100nm was approximately 1.7 times higher than that of a comparable electrodeposit with no particles. However, significant variations in microhardness were not observed between the nanocomposites with grain sizes of 20 nm and the comparable electrodeposit.

Preparation of Cu2(btc)3-AAO Hybrid Membrane by Layer-by-layer Technique (Layer-by-layer 기법을 통한 Cu2(btc)3-AAO 하이브리드 분리막의 제조)

  • Yoo, Hyeonseok;Choi, Jinsub
    • Journal of the Korean institute of surface engineering
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    • v.51 no.1
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    • pp.21-26
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    • 2018
  • The $Cu_2(btc)_3$ metal-organic frameworks (MOF) coated anodic aluminum oxide (AAO) membrane was successfully prepared by layer-by-layer technique using hand spray method. It was confirmed that the $Cu_2(btc)_3$ layer, which has the pore sized in 2-3 nm, on surface of AAO exhibited the polycrystalline thin film structure by XRD analysis. More than 100 repetitive spray cycles were required to obtain more robust and thick MOFs on AAO and it was possible to uniformly coat both the top and bottom surfaces of the AAO. It should be noted that the MOFs also could be coated on surface of pores resulting in reduce the size of pore from 52 nm to 32 nm.

Crystal Growth of Yb:YAG by Floating Zone Method and Their Optical Properties (부유대용융법에 의한 Yb-YAG 단결정 성장 및 광특성)

  • 이성영;김병호;정석종;유영문
    • Korean Journal of Crystallography
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    • v.11 no.3
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    • pp.151-156
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    • 2000
  • Yb/YAG single crystals were grown from the melt composition of Y/sub 1-x/Yb/sub x/)₃Al/sub 5/O/sub 12/ where x equal to 5, 10, 15, 20, 25, 33, 50, 75 and 100 at % by floating zone method. Optimum growth parameters to get high quality single crystals were 3.5 mm/h of growth rate and 20 rpm of rotation rate under the N₂ atmosphere. After the growth, color of crystals was appeared with pale blue due to the lack of oxygen, but it was disappeared after annealing at 1450℃ for 2 hr. Absorption coefficients were linearly increased depending on the concentration of Yb/sup 3+/ ions. Broad emission band was measured in the range of 1020 to 1050 nm with the peak intensity at 1031 nm and 1051 nm because of ²F/sub 5/2/(1)→²F/sub 7/2/(3) and ²F/sub 5/2/(1)→²F/sub 7/2/(4) transition respectively. When Yb/sup 3+/ ions were substituted with high rates, there were tendency to decrease the measured fluorescent lifetime for Yb ions depending on the concentration of Yb/sup 3+/ ions.

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