• Journal of Powder Materials
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• v.15 no.6
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• pp.489-495
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• 2008

Colored tantalum oxy-nitride (TaON) and tantalum nitride ($Ta_{3}N_{5}$) were synthesized by ammonolysis. Oxygen deficient tantalum oxides ($TaO_{1.7}$) were produced by a titration process, using a tantalum chloride ($TaCl_5$) precursor. The stirring speed and the amount of $NH_{4}OH$ were important factors for controling the crystallinity of tantalum oxides. The high crystallinity of tantalum oxides improved the degree of nitridation which was related to the color value. Synthesized powders were characterized by XRD, SEM, TEM and Colorimeter.

• Transactions on Electrical and Electronic Materials
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• v.4 no.6
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• pp.32-37
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• 2003

In this paper, the trap characteristics of thin silicon oxides is investigated in the ULSI implementation with nano structure transistors. The stress and transient currents associated with the on and off time of applied voltage were used to measure the distribution of high voltage stress induced traps in thin silicon oxide films. The stress and transient currents were due to the charging and discharging of traps generated by high stress voltage in the silicon oxides. The transient current was caused by the tunnel charging and discharging of the stress generated traps nearby two interfaces. The stress induced leakage current will affect data retention in electrically erasable programmable read only memories. The oxide current for the thickness dependence of stress current, transient current, and stress induced leakage currents has been measured in oxides with thicknesses between 113.4nm and 814nm, which have the gate area 10$\^$-3/ $\textrm{cm}^2$. The stress induced leakage currents will affect data retention, and the stress current and transient current is used to estimate to fundamental limitations on oxide thicknesses.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.124-127
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• 1997

The magnetic properties of calcined Sr-ferrites, related to the iron oxides, produced from three different process in steel plants, have been investigated. The powder f.characteristics of iron oxides are much affected on the magnetic properties of calcined Sr-ferrite Powders. It was possible to improve the magnetic property of calcined Sr-ferrites with the iron oxide powders of small size and narrow size distribution. The maximum magnetic properties of calcined Sr-ferrites, showing 69 emu/g of saturation magnetization and 4020 Oe of intrinsic coercivity, are achieved at the following conditions; the iron oxides from the chemirite process(EP), mole ratio of 5.8, and calcination condition of 120$0^{\circ}C$/1hr.

• Journal of the Korean institute of surface engineering
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• v.40 no.4
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• pp.180-184
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• 2007

A new zirconium alloy, low-Sn Zircaloy-4 was investigated to see the effects of high pressure steam on the oxidation at high temperatures. High pressure steam turned out to enhance the oxidation at high temperatures below $1000^{\circ}C$. The oxide layer groved to deviate from the uniform layer under high steam pressures, and usually cracks were found at the thicker parts in the oxide layer. High pressure steam seems to destabilize the tetragonal oxides near the metal layer, and the monoclinic oxides transformed from the destabilized tetragonal oxides are structurally not sound, resulting in enhanced oxidation under high pressure steam.

• Bulletin of the Korean Chemical Society
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• v.20 no.12
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• pp.1457-1463
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• 1999

Structure and their redox property of the vanadium oxides prepared by decomposing NH₄VO₃ at various temperatures were studied by XRD, SEM, XPS, and temperature programmed reduction/temperature programmed oxidation (TPR/TPO) experiment. All TPR profiles have two sharp peaks in the temperature range 650-750℃, and the area ratio of the two sharp peaks changed from sample to sample. There were three redox steps in TPR/TPO profiles. The oxidation proceeded in the reverse order of the reduction process, and both the reactions proceeded via quite a stable intermediates. The changes of the morphological factor $(I_{(101)}/I_{(010)})$, the ratio of $O_{1S}$ peak area (O$_{1S}$( α)/O$_{1S}$( β)) in the XPS results, and the ratio of hydrogen consumption in TPR profiles with various vanadium oxides showed the distinct relationship between the structural property and their redox property of vanadium oxides. The change of the specific yield of phthalic anhydride with various vanadium oxides showed a very similar trend to those of the peak area ratio in TPR profiles, which meant that the first reduction step related to the partial oxidation of o-xylene on the vanadium oxide catalyst.

• Bulletin of the Korean Chemical Society
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• v.23 no.6
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• pp.797-799
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• 2002

• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.1
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• pp.66-79
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• 2008

Several oxides have recently been reported to have resistance-switching characteristics for nonvolatile memory (NVM) applications. Both binary and ternary oxides demonstrated great potential as resistive-switching memory elements. However, the switching mechanisms have not yet been clearly understood, and the uniformity and reproducibility of devices have not been sufficient for gigabit-NVM applications. The primary requirements for oxides in memory applications are scalability, fast switching speed, good memory retention, a reasonable resistive window, and constant working voltage. In this paper, we discuss several materials that are resistive-switching elements and also focus on their switching mechanisms. We evaluated non-stoichiometric polycrystalline oxides ($Nb_2O_5$, and $ZrO_x$) and subsequently the resistive switching of $Cu_xO$ and heavily Cu-doped $MoO_x$ film for their compatibility with modem transistor-process cycles. Single-crystalline Nb-doped $SrTiO_3$ (NbSTO) was also investigated, and we found a Pt/single-crystal NbSTO Schottky junction had excellent memory characteristics. Epitaxial NbSTO film was grown on an Si substrate using conducting TiN as a buffer layer to introduce single-crystal NbSTO into the CMOS process and preserve its excellent electrical characteristics.

• Toxicological Research
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• v.31 no.2
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• pp.181-189
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• 2015

In recent years, the use of both nano- and micro-sized lanthanum has been increasing in the production of optical glasses, batteries, alloys, etc. However, a hazard assessment has not been performed to determine the degree of toxicity of lanthanum. Therefore, the purpose of this study was to identify the toxicity of both nano- and micro-sized lanthanum oxide in cultured cells and rats. After identifying the size and the morphology of lanthanum oxides, the toxicity of two different sized lanthanum oxides was compared in cultured RAW264.7 cells and A549 cells. The toxicity of the lanthanum oxides was also analyzed using rats. The half maximal inhibitory concentrations of micro-$La_2O_3$ in the RAW264.7 cells, with and without sonication, were 17.3 and 12.7 times higher than those of nano-$La_2O_3$, respectively. Similar to the RAW264.7 cells, the toxicity of nano-$La_2O_3$ was stronger than that of micro-$La_2O_3$ in the A549 cells. We found that nano-$La_2O_3$ was absorbed in the lungs more and was eliminated more slowly than micro-$La_2O_3$. At a dosage that did not affect the body weight, numbers of leukocytes, and concentrations of lactate dehydrogenase and albumin in the bronchoalveolar lavage (BAL) fluids, the weight of the lungs increased. Inflammatory effects on BAL decreased over time, but lung weight increased and the proteinosis of the lung became severe over time. The effects of particle size on the toxicity of lanthanum oxides in rats were less than in the cultured cells. In conclusion, smaller lanthanum oxides were more toxic in the cultured cells, and sonication decreased their size and increased their toxicity. The smaller-sized lanthanum was absorbed more into the lungs and caused more toxicity in the lungs. The histopathological symptoms caused by lanthanum oxide in the lungs did not go away and continued to worsen until 13 weeks after the initial exposure.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.447-452
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• 2003

We had clarified the reactions of the rare earth oxides($RE_2O_3$) with lithium oxide produced in lithium reduction process of oxide fuels. Oxides of scandium, yttrium, praseodymium, neodymium, samarium, europium, gadolinium, ytterbium and lutetium reacted with lithium oxide in the higher concentration than the respective certain critical concentration of lithium oxide and formed complex oxides($LiREO_2$). The critical lithium oxide concentrations for the formation of complex oxides of scandium, yttrium, praseodymium, neodymium, samarium, europium, gadolinium, ytterbium and lutetium oxide were respectively 0.1 wt%, 1.9 wt%, 5.3 wt%, 5.0 wt%, 3.0 wt%, 3.9 wt% 2.9 wt%, 2.6 wt% and 0.3 wt%. Cerium and lanthanum oxide did not react with lithium oxide. These complex oxides obtained from experiments have limited solubility in lithium chloride at $650^{\circ}C$.

• Applied Chemistry for Engineering
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• v.10 no.8
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• pp.1161-1168
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• 1999

The redox property of oxide materials of the 3rd period transition metals(Cr~Zn), V, Mo, and W was studied with temperature-programmed reduction/temperature-programmed oxidation(TPR/TPO) experiment. The peak temperatures of TPO spectra were equal to or lower than those of TPR spectra. And the peak shapes of TPO spectra were broader than those of TPR ones. The activation energies of TPR/TPO for the oxides of the 3rd period transition metals showed in the range of 33~149 kJ/mol, while for the oxides of V, Mo, and W, they showed relatively higher values. The change of activation energies of TPR/TPO with various metal oxides showed a similar trend to the change of their metal-oxygen bond strengths. The change of activation energies of o-xylene oxidation for various metal oxides was proportional to the difference (${\Delta}E_a$) between the activation energy of TPR and that of TPO. From these results, we concluded that the oxidation of o-xylene over various metal oxide catalysts follows the Mars-van Krevelen mechanism including the surface reduction-oxidation of the metal oxide itself.