• Progress in Superconductivity and Cryogenics
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• v.17 no.4
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• pp.8-11
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• 2015

We studied on the visible emission of Cu-ion-doped perovskite hafnate $SrHfO_3$ (SHO:Cu) with the photo-excitation energy dependence. The polycrystalline SHO:Cu samples were newly synthesized in the solid state reaction method. From the X-ray diffraction measurement it was found that the crystalline structure of SHO:Cu is nearly identical to that of undoped $SrHfO_3$. Interestingly, the photoluminescence excitation (PLE) spectra change significantly with the emission energy, which is linked to the strong dependence of the visible emission on the photo-excitation energy. This unusual emission behavior is likely to be associated with the mixed valence states of the doped Cu ions, which were revealed by X-ray photoelectron spectroscopy. We compared our finding of tunable visible emission in the SHO:Cu compounds with the cases of similar materials, $SrTiO_3$ and $SrZrO_3$ with Cu-ion-doping.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.6
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• pp.1204-1210
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• 1998

This study was focused on the purification, characterization and promotion mode of an anticoagulant polysaccharide from Hizikia fusiforme. The anticoagulant crude polysaccharide(HF 0) was obtained by using hot water extraction at 100oC for 3 hrs after homogenizing desalted Hizikia fusiforme. The anticoagulant polysaccharide(HF 2 3 1a) was purified from the crude extract(HF 0) through stepwise gradient ethanol precipitation(HF 2), DEAE Toyopearl 650C(HF 2 3), Sephadex G 75(HF 2 3 1), Sepharose CL 6B(HF 2 3 1a) chromatography and HPLC to homogeneity. HF 2 3 1a was estimated at 5.3$\times$105 Da molecular weight and composed of fucose(51.92%), galactose(19.34%), mannose(13.92%), xylose (7.14%), arabinose(3.95%) and rhamnose(3.78%), and comprimised 29.7 % sulfate residue. The sulfated anticoagulant polysaccharide from HF 2 3 1a was proposed to inhibit via the intrinsic pathway and common pathway in the blood coagulation. The HF 2 3 1a exhibited the anticoagulant activity by activating an antithrombin III and the activity depended on the concentration of HF 2 3 1a. Acute toxicity of HF 2 in mice was not detected. Only 14 of 33 control mice(11.4%) that had taken saline survived for 30 min after injecting thrombin(100 NIH unit/ml).

• Transactions on Electrical and Electronic Materials
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• v.15 no.5
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• pp.241-244
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• 2014

Charge trap flash memory capacitors incorporating $(HfO_2)_x(Al_2O_3)_{1-x}$ film, as the charge trapping layer, were fabricated. The effects of the charge trapping layer composition on the memory characteristics were investigated. It is found that the memory window and charge retention performance can be improved by adding Al atoms into pure $HfO_2$; further, the memory capacitor with a $(HfO_2)_{0.9}(Al_2O_3)_{0.1}$ charge trapping layer exhibits optimized memory characteristics even at high temperatures. The results should be attributed to the large band offsets and minimum trap energy levels. Therefore, the $(HfO_2)_{0.9}(Al_2O_3)_{0.1}$ charge trapping layer may be useful in future nonvolatile flash memory device application.

• Proceedings of the Materials Research Society of Korea Conference
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• 1997.10a
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• pp.149-149
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• 1997

• Journal of the Korean Chemical Society
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• v.42 no.6
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• pp.629-637
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• 1998

The HF-SCF, MP2 and B3LYP calculations have been performed on the two conceivable clusters $(HF)_2(CO)$ trimers as well as their dimer complexes FH…FH, FH…CO and FH…OC applying $6-31+G^{\ast}^{\ast}$, and $6-311+G^{\ast}^{\ast}$ basis sets. A variety of ground state properties of these trimer complexes have been listed, and compared with corresponding properties of isolated monomers and combined dimers. It was calculated that FH…CO is more stable than FH…OC by average 0.85 kcal/mol and F-H…F-H…C≡O is more stable than F-H…F-H…O≡C by 1-2 kcal/mol. The C≡O stretching bands of the F-H…F-H…C≡O and F-H…F-H…O≡C were red shifted by 24, $37\;cm^{-1}$ compared with the FH…CO and FH…OC respectively. Also, H-F stretching bands were red shifted by 54 and $353\;cm^{-1}$.

• Progress in Superconductivity and Cryogenics
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• v.13 no.1
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• pp.6-11
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• 2011

The $BaHfO_3$ (BHO) buffer layer on the IBAD MgO template was turned to be effective for a successful fabrication of $GdBa_2Cu_3O_{7-{\delta}}$ (GdBCO) films with high critical current density ($J_c$). Both the BHO buffer layers and GdBCO films were prepared by pulsed laser deposition (PLD). The effects of the PLD conditions, including substrate temperature ($T_s$), oxygen partial pressure ($PO_2$), and deposition time on the in-plane texture, surface roughness, and microstructures of the BHO buffer layers on the IBAD MgO template were systematically studied for processing optimization. The c-axis oriented growth of BHO layers was insensitive to the deposition temperature and the film thickness, while the in-plane texture and surface roughness of those were improved with increasing $T_s$ from 700 to $800^{\circ}C$. On the optimally processed BHO buffer layer, the highest $J_c$ value (77 K, self-field) of 3.68 $MA/cm^2$ could be obtained from GdBCO film deposited at $780^{\circ}C$, representing that BHO is a strong candidate for the buffer layer on the IBAD MgO template.

• Bulletin of the Korean Chemical Society
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• v.24 no.6
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• pp.853-858
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• 2003

The reaction mechanism of the pyrolysis of sulphonyl oximes ($CH_3-C_6H_4-S(O)_2O-N=C(H)-C_6H_4Y$), in the gas phase is studied theoretically at HF/3-21G, ONIOM (B3LYP/6-31G**:HF/3-21G) and ONIOM (MP2/6- 31G**:HF/3-21G) levels. All the calculations show that the thermal decomposition of sulphonyl oximes is a concerted asynchronous process via a six-membered cyclic transition state. The activation energies (Ea) predicted by ONIOM (B3LYP/6-31G**: HF/3-21G) method are in good agreement with the experimental results for a series of tosyl arenecarboxaldoximes. Five para substituents, Y = $OCH_3$, $CH_3$, H, Cl, and $NO_2$, are employed to investigate the substituent effect on the elimination reaction. Linear Hammett correlations are obtained in all calculations in contrast to the experimental finding.

• 전기의세계
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• v.27 no.3
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• pp.43-46
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• 1978

The prezoelectric ceramic specimen compoxed of PbO, ZrO$_{2}$, TiO$_{2}$ were prepared in this Lab, and showed properties of dielectric constant .epsilon.$^{33}$ /.epsilon.$_{0}$ 487 at 1kHz, electromechanical coefficient Kr 0.524. As the characteristics of piezoelectric HF filter used these piezoelectric specimen were the resonant point 6.7 MHz, effective bandwidth 690KHz, it was exellant. Since a LC resonant filter can be replaced bt this piezoelectric HG filter, it will greatly contribute to compose a compact circuit. If the resont point can be controlled, this piezoelectric HF filter practically.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.319.1-319.1
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• 2016

Recently, the Al-doped ZnO (ZnO:Al) films are intensively used in thin film a-Si solar cell applications due to their high transmittance and good conductivity. The textured ZnO:Al films are used to enhance the light trapping in thin film solar cells. The wet etch process is used to texture ZnO:Al films by dipping in diluted acidic solutions like HCl or HF. During that process the glass substrate could be damaged by the acidic solution and it may be difficult to apply it for the inline mass production process since it has to be done outside the chamber. In this paper we report a new technique to control the surface morphology of RF-sputtered ZnO:Al films. The ZnO:Al films are textured with vaporized HF formed by the mixture of HF and H2SiO3 solution. Even though the surface of textured ZnO:Al films by vapor etching process showed smaller and sharper surface structures compared to that of the films textured by wet etching, the haze value was dramatically improved. We achieved the high haze value of 78% at the wavelength of 540 nm by increasing etching time and HF concentration. The haze value of about 58% was achieved at the wavelength of 800 nm when vapor texturing was used. The ZnO:Al film texture by HCl had haze ratio of about 9.5 % at 800 nm and less than 40 % at 540 nm. In addition to low haze ratio, the texturing by HCl was very difficult to control etching and to keep reproducibility due to its very fast etching speed.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.164-164
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• 2010

The impurity doped ZnO has been extensively studied because of its optoelectric properties. GIZO (Ga-In-Zn-O) amorphous oxide semiconductors has been widely used as transparent flexible semiconductor material. Recently, various amorphous transparent semiconductors such as IZO (In-Zn-O), GIZO, and HIZO (Hf-In-Zn-O) were developed. In this work, we examined the local structures of IZO, GIZO, and HIZO. The local coordination structure was investigated by the extended X-ray absorption fine structure. The IZO, GIZO and HIZO thin films ware deposited on the glass substrate with thickness of 400nm by the radio frequency sputtering method. The targets were prepared by the mixture of $In_2O_3$, ZnO and $HfO_2$ powders. The percent ratio of In:Zn in IZO, Ga:In:Zn in GIZO and Hf:In:Zn in HIZO was 45:55, 33:33:33 and 10:35:55, respectively. In this work, we found that IZO, GIZO and HIZO are all amorphous and have a similar local structure. Also, we obtained the bond distances of $d_{Ga-O}=1.85\;{\AA}$, $d_{Zn-O}=1.98\;{\AA}$, $d_{Hf-O}=2.08\;{\AA}$, $d_{In-O}=2.13\;{\AA}$.