• Korean Journal of Materials Research
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• v.30 no.12
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• pp.655-659
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• 2020

Hydrogen isotopes (i.e. deuterium and tritium) are supplied to the tokamak in the International Thermonuclear Experimental Reactor (ITER) fuel cycle. One important part of the ITER fuel cycle is the recycling of unused fuel back to the tokamak, as almost 99 % of fuel is unburned during fusion reaction. For this, cryogenic distillation has been used in the isotope separation system (ISS) of ITER, but this technique tends to be energy-intensive and to have low selectivity (typically below 1.5 at 24 K). Recently, efficient isotope separation by porous materials has been reported in the so-called quantum sieving process. Hence, in this study, hydrogen isotope adsorption behavior is studied using chemically stable ZIF-11. At low temperature (40 K ~ 70 K), the adsorption increases and the sorption hysteresis becomes stronger as the temperature increases to 70K. Molar ratio of deuterium to hydrogen based on the isotherms shows the highest (max. 14) ratio at 50 K, confirming the possibility of use as a potential isotope separation material.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.3
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• pp.264-268
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• 2022

High pressure deuterium (HPD) annealing is an advancing technology for the fabrication of modern semiconductor devices. In this work, gate-enclosed FETs are fabricated on a silicon substrate as test vehicles. After a cycle for the HPD annealing, the device parameters such as threshold voltage (V_TH), subthreshold swing (SS), on-state current (I_ON), off-state current (I_OFF), and gate leakage (I_G) were measured and compared depending on the HPD. The HPD annealing can passivate the dangling bonds at Si-SiO₂ interfaces as well as eliminate the bulk trap in SiO₂. It can be concluded that adding the HPD annealing as a fabrication process is very effective in improving device reliability, performance, and variability.

• Korean Journal of Materials Research
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• v.32 no.1
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• pp.36-43
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• 2022

Breakthrough analysis has widely been explored for the dynamic separation of gaseous mixtures in porous materials. In general, breakthrough experiments measure the components of a flowing gas when a gaseous mixture is injected into a column filled with an adsorbent material. In this paper, we report on the design and fabrication of a breakthrough curve measurement device to study the dynamic adsorptive separation of hydrogen isotopologues in porous materials. Using the designed system, an experiment was conducted involving a 1:1 mixture of hydrogen and deuterium passed through a column filled with zeolite 13X (1 g). At room temperature, both hydrogen and deuterium were adsorbed in negligible amounts; however, at a temperature of 77 K, deuterium was preferentially adsorbed over hydrogen. The selectivity was different from that in the existing literature due to the different sample shapes, measurement methods, and column structures, but was at a similar level to that of cryogenic distillation (1.5).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.1
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• pp.43-47
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• 2024

The size of semiconductor devices has been scaled down to improve packing density and output performance. However, there is uncontrollable spreading of the dopants that comprise the well, punch-stop, and channel-stop when using high-temperature annealing processes, such as rapid thermal annealing (RTA). In this context, low-temperature deuterium annealing (LTDA) performed at a low temperature of 300℃ is proposed to reduce the thermal budget during CMOS fabrication. The LTDA effectively eliminates the interface trap in the gate dielectric layer, thereby improving the electrical characteristics of devices, such as threshold voltage (V_TH), subthreshold swing (SS), on-state current (I_ON), and off-state current (I_OFF). Moreover, the LTDA is perfectly compatible with CMOS processes.

• Nuclear Engineering and Technology
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• v.52 no.12
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• pp.2860-2866
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• 2020

Oxide dispersion-strengthened materials W-1wt%Pr₂O₃ and W-1wt%La₂O₃ were synthesized by wet chemical method and spark plasma sintering. The field emission scanning electron microscopy (FE-SEM) analysis, XRD and Vickers microhardness measurements were conducted to characterize the samples. The irradiations were carried out with a 5 keV helium ion beam to fluences up to 5.0 × 10²¹ ions/m² under 600 ℃ using the low-energy ion irradiation system. Transmission electron microscopy (TEM) study was performed to investigate the microstructural evolution in W-1wt%Pr₂O₃ and W-1wt%La₂O₃. At 1.0 × 10²⁰ He⁺/m², the average loops size of the W-1wt%Pr₂O₃ was 4.3 nm, much lower than W-1wt% La₂O₃ of 8.5 nm. However, helium bubbles were not observed throughout in both doped W materials. The effects of pre-irradiation with 1.0 × 10²¹ He⁺/m² on trapping of injected deuterium in doped W was studied by thermal desorption spectrometry (TDS) technique using quadrupole mass spectrometer. Compared with the samples without He⁺ pre-irradiation, deuterium (D) retention of doped W materials increased after He⁺ irradiation, whose retention was unsaturated at the damage level of 1.0 × 10²²D₂⁺/m². The present results implied that irradiation effect of He⁺ ions must be taken into account to evaluate the deuterium retention in fusion material applications.

• Bulletin of the Korean Chemical Society
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• v.10 no.4
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• pp.393-394
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• 1989

• Bulletin of the Korean Chemical Society
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• v.19 no.4
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• pp.488-491
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• 1998

• Journal of Photoscience
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• v.9 no.2
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• pp.299-301
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• 2002

Recent denaturation experiments of bacteriorhodopsin (bR) in the dark and under illumination at high temperatures revealed that irreversible thermal bleaching occurs above ~ 70°C and the preceding reversible structural changes in the dark above 60°C are closely related to irreversible photobleaching observed in the same temperature range (Yokoyama et al. (2002). J Biochem. 131,785). In this study, structural properties of bacteriorhodopsin (bR) at high temperatures were extensively probed by hydroxylamine reactivity with the Schiff base in the dark and hydrogen-deuterium (H-D) exchange in the peptide groups. In the Arrhenius plot from kinetics measurements of the hydroxylamine reaction, a good linear relationship between the reaction time constant and the inverse of the absolute temperature was observed below 60°C, while significant increase started above 60°C, suggesting that remarkable increase in water accessibility of the Schiff base in the temperature region. FT-IR spectroscopic studies on the H-D exchange suggested increase in the deuterium exchanges rate of the peptide hydrogen in the same temperature region.

• Bulletin of the Korean Chemical Society
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• v.32 no.11
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• pp.3880-3886
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• 2011

The nucleophilic substitution reactions of diisopropyl thiophophinic chloride (3) with substituted anilines ($XC_6H_4NH_2$) and deuterated anilines ($XC_6H_4ND_2$) are investigated kinetically in acetonitrile at $65.0^{\circ}C$. The anilinolysis rate of 3 is rather slow to be rationalized by the conventional stereoelectronic effects. The obtained deuterium kinetic isotope effects (DKIEs; $k_H/k_D$) are secondary inverse ($k_H/k_D$ = 0.80-0.96). The anilinolyses of ten P=S systems in MeCN are reviewed on the basis of DKIEs and selectivity parameters to obtain systematic information on the DKIEs and mechanism for thiophosphoryl transfer reactions. The steric effects of the two ligands on reactivity, DKIEs, mechanism, and substituent effects of the nucleophile (X) on the DKIEs are discussed.

• Bulletin of the Korean Chemical Society
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• v.33 no.10
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• pp.3274-3278
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• 2012

The kinetic studies on the reactions of phenyl N-phenyl phosphoramidochloridate (8) with substituted anilines ($XC_6H_4NH_2$) and deuterated anilines ($XC_6H_4ND_2$) have been carried out in acetonitrile at $60.0^{\circ}C$. The obtained deuterium kinetic isotope effects (DKIEs; $k_H/k_D$) are huge secondary inverse ($k_H/k_D$ = 0.52-0.69). A concerted mechanism is proposed with a backside attack transition state (TS) on the basis of the secondary inverse DKIEs and the variation trends of the $k_H/k_D$ values with X. The degree of bond formation in the TS is really extensive taking into account the very small values of the DKIEs. The steric effects of the two ligands on the rates are extensively discussed for the aminolyses of the chlorophosphate-type substrates on the basis of the Taft equation.