• Journal of the Korean Society of Radiology
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• v.12 no.4
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• pp.451-457
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• 2018

Luminescence properties of $NaCa(PO_3)_3$ doped with $Tb^{3+}$ ions are investigated by optical and laser excitation spectroscopy. The phosphors were prepared by solidstate reaction method The X-ray diffraction(XRD) was used to analyze the crystal structure and the crystallinity of the samples. The excitation and emission spectra and decay curve of $NaCa(PO_3)_3:Tb^{3+}$(0.01 ~ 30mol%) were measured at room temperature. The f - d band of $Tb^{3+}$ is observed in the excitation spectra of $NaCa(PO_3)_3:Tb^{3+}$ in the wave length region 205 ~ 245 nm. Strong emission lines due to the $^5D_4{\rightarrow}^7F_J$ transition and weak emission lines due to the $^5D_4{\rightarrow}^7F_J$ transition are observed in the emission spectra of $NaCa(PO_3)_3:Tb^{3+}$. The energy transfer and cross relaxation between $Tb^{3+}$ ions are discussed in $NaCa(PO_3)_3:Tb^{3+}$ in the emission spectra and life time.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.9
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• pp.947-952
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• 2004

Tb-doped lead zirconate titanate(Pb(Zr$\_$0.6/,Ti$\_$0.4/)O$_3$; PZT) thin films on Pt(111)/Ti/SiO$_2$/Si(100) substrates were fabricated by the sol-gel method. The effect on the structural and electrical properties of films measured according to Tb content. The dielectric and ferroelectric properties of Tb-doped PZT thin films were altered significantly by Tb-doping. The PZT thin film with higher dielectric constant and improved leakage current characteristic was obtained by adding 0.3 mol% Tb. The relative dielectric constant and the dielectric loss of the 0.3 mol% Tb-doped PZT thin film were 1611 and 0.024, respectively. Typical value of the swichable remanent poaraization(2Pr) and the coercive filed of the PZT film capacitor for 0.3 mol% Tb-doped were 61.4 ${\mu}$C/cm$^2$ and 61.9 kV/cm, respectively. Tb-doped PZT thin films showed improved fatigue characteristics comparing to the undoped PZT thin film.

• Transactions on Electrical and Electronic Materials
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• v.8 no.3
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• pp.105-109
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• 2007

The microstructure and electrical properties of Zn-Pr-Co-Cr-Tb oxide-based varistors were investigated for different $Tb_4O_7$ amounts. As the $Tb_4O_7$ amount increased, the average grain size decreased from 7.7 to $4.8{\mu}m$ and the sintered density increased from 5.73 to $5.84g/cm^3$. As the $Tb_4O_7$ amount increased, the varistor voltage increased from 280.9 to 715.8V/mm and the nonlinear coefficient increased from 26.4 to 44.4. It is assumed that these varistors can be applied for high power with compact size.

• Journal of Periodontal and Implant Science
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• v.47 no.1
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• pp.20-29
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• 2017

Purpose: The microstructural characteristics of trabecular bone were identified using micro-computed tomography (micro-CT), in order to develop a potential strategy for implant surface improvement to facilitate osseointegration. Methods: Alveolar bone specimens from the cadavers of 30 humans were scanned by high-resolution micro-CT and reconstructed. Volumes of interest chosen within the jaw were classified according to Hounsfield units into 4 bone quality categories. Several structural parameters were measured and statistically analyzed. Results: Alveolar bone specimens with D1 bone quality had significantly higher values for all structural parameters than the other bone quality categories, except for trabecular thickness (Tb.Th). The percentage of bone volume, trabecular separation (Tb.Sp), and trabecular number (Tb.N) varied significantly among bone quality categories. Tb.Sp varied markedly across the bone quality categories (D1: $0.59{\pm}0.22mm$, D4: $1.20{\pm}0.48mm$), whereas Tb.Th had similar values (D1: $0.30{\pm}0.08mm$, D4: $0.22{\pm}0.05mm$). Conclusions: Bone quality depended on Tb.Sp and number-that is, endosteal space architecture-rather than bone surface and Tb.Th. Regardless of bone quality, Tb.Th showed little variation. These factors should be taken into account when developing individualized implant surface topographies.

• 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 ⁵D₄→⁷F₅ magnetic dipole transition of Tb³⁺ and three weak emission bands at 489, 586, and 620 nm, respectively. The intensity of the ⁵D₄→⁷F₅ (546 nm) magnetic dipole transition was greater than that of the ⁵D₄→⁷F₆ (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.

• Journal of the Korean Ceramic Society
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• v.41 no.1
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• pp.92-95
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• 2004

Using the Micro-Pulling Down (${\mu}$-PD), $MnO_2$ and $Tb_4O_7$ co-doped crack-free stoichiometric $LiNbO_3$ single crystals were grown in 1.0 mm diameter and 25-30 mm length for c-axis. The homogeneous distributions of $MnO_2$ and $Tb_4O_7$ concentration were confirmed by the Electron Probe Microanalysis (EPMA). Also, the infrared OH absorption band of the single crystals observed by using a Fourier Transform-Infrared Spectrophotometer (FT-IR) at room temperature and the photoluminescence spectra was measured with respect to the $MnO_2$ and $Tb_4O_7$ doping.

• Korean Journal of Materials Research
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• v.12 no.9
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• pp.761-766
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• 2002

Fine $LaPO_4$:Tb phosphor particles with spherical shape were prepared by spray pyrolysis. The influence of the precursor type of phosphorous such as ($NH_4$)$_2$$HPO_4$, $NH_4$$H_2$$PO_4$, ($NH_4$)$_3$$PO_4$ and $H_3$$PO_4$ on the morphology and brightness of particles was investigated. As-prepared particles by spray pyrolysis had spherical shape when ($NH_4$)$_2$ $HPO_4$ and $NH_4$$H_2$$PO_4$ were used as the precursor of phosphorous. The precursor type of phosphorous affected the photoluminescence intensity of $LaPO_4$:Tb phosphor particles, but not significant. With changing the content of activator(Tb) and excess of phosphorous, the optimal composition giving the highest photoluminescence intensity was found. The spherical morphology of prepared $LaPO_4$:Tb particles was completely maintained even after the posttreatment up to $1050^{\circ}C$. When the posttreatment temperature was over $1100^{\circ}C$, the particles did not have the spherical shape anymore. However, the highest photoluminescence intensity of prepared $LaPO_4$:Tb particles was obtained at $1050^{\circ}C$. The photoluminescence characteristics of prepared $_LaPO4$:Tb under the vacuum ultraviolet(VUV) illumination was comparable with that of the commercial $Zn_2$$V_4$:Mn and (La,Ce)PO$_4$:Tb phosphor particles. At the optimal condition, the decay time of prepared spherical $LaPO_4$:Tb phosphor particles was about 6.8ms.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.9
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• pp.878-882
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• 2006

We have fabricated single organic layer devices of the organolanthanide complex, terbium tris-(1-phenyl-3-methyl-4-(tertiarybutyry)pyrazol-5-one)triphenylphosphine oxide [$(tb-PMP)_{3}Tb-(Ph_{3}PO)$] for the investigation of its light emission and electrical conduction properties. The thickness of ($(tb-PMP)_{3}Tb-(Ph_{3}PO)$) layer was varied to 60, 75, 95 nm. Mg and Ca layers were used for the cathode contact. The electrical conduction in the $(tb-PMP)_{3}Tb-(Ph_{3}PO)$ single layer devices was dominated by the injection of electrons into the organic layer from the cathode. A higher current density at much lower voltages can be attained with Ca cathode because of the enhanced electron injection. The device shows very sharp emission at 548 nm. The FWHM of the strongest emission peak was 12 nm.

• Pediatric Infection and Vaccine
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• v.26 no.2
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• pp.89-98
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• 2019

Purpose: Despite the decline in tuberculosis (TB) incidence and mortality rates in the Republic of Korea through a national TB control program, TB remains one of the most critical infectious diseases in Korean children. We investigated the trends and research areas of published articles on TB in Korean children and adolescents. Methods: In 6 Korean and overseas databases, we searched titles and abstracts including "tuberculo*" or "TB," "child*" or "adolescen*" or "neonat*" or "infant*" or "pediatric*," and "korea*." The publication type, publication year, research areas, journal title, and research subjects were analyzed. Results: Out of the 257 searched documents, 120 papers were included in the analysis. Of these, 82 were original articles (68.3%), 33 case reports (27.5%), 4 review articles (3.3%), and 1 guideline (0.8%). In the original articles, the most common subject of studies was the clinical characteristics of patients with TB (36.6%), followed by diagnostics (29.3%), contact investigations (9.8%), epidemiology (6.1%), treatment (4.9%), vaccine (3.6%), latent TB infection (3.6%), complications (3.6%), and surveys on perception of TB (2.4%). From 1962, 4 articles were published in the 1960s, 10 articles in the 1970s, 11 articles in the 1980s, 22 articles in the 1990s, 26 articles in the 2000s, and 47 articles since 2010. Conclusions: The amount of research on TB in Korean children has increased over the past 5 decades; however, it has mainly focused on the clinical characteristics and diagnostics. Research in different areas, such as treatment and vaccine, is needed in the future.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.4
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• pp.264-270
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• 2013

$CaMoO_4:Tb^{3+}$ green phosphor powders and thin films were successfully prepared by using the solid-state reaction method and the radio-frequency magnetron sputtering technique, respectively. The crystalline structure of all phosphor powders with different $Tb^{3+}$ ion concentrations was found to be a tetragonal system with the maximum diffraction intensity at $28.58^{\circ}$, while that of the phosphor thin films, irrespective of the type of substrate, was amorphous. As for the phosphor powders, the grain particles showed the chain-like patterns with inhomogeneous size distribution, the excitation spectra were composed of a broad band peaked at 307 nm and two small narrow bands centered at 381 and 492 nm, and the highest green emission spectrum was observed at 0.01 mol of $Tb^{3+}$ ions. As for the phosphor thin films, the average transmittance exceeding 85% was measured in the 400~1,100 nm range and the optical band gap showed a significant dependence on the type of substrate.