• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.307-310
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• 1998

In this paper, $Al_2$O$_3$/MgO belayer was prepared with Electron-beam evaporation and the properties of the film was investigated in order to improve the property of MgO film, which is used for the protection layer in PDP(Plasma Display Panel). $Al_2$O$_3$/MgO belayer were improved of roughness and it were condensed by annealing, and the result of XPS analysis for $Al_2$O$_3$/MgO belayer unchanged binding energy. To investigate electric characteristics, discharge properties of $Al_2$O$_3$/MgO belayer were compared with discharge minimum voltage for MgO monolayer through Ar discharge experiments.

• Journal of the Korean Ceramic Society
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• v.31 no.10
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• pp.1147-1158
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• 1994

From Zr(O-nC3H7)4-H2O-C2H5OH-HNO3 starting solutions, MgO-doped stabilized zirconia fibers with varying content of MgO (10~18 mol%) from different MgO sources were fabricated by sol-gel method. The MgO sources used are magnesium nitrate hexahydrate, magnesium acetate tetrahydrate, and magnesium ethylate. The phase transformation studies of a drawn MgO-ZrO2 fiber were carried out using X-ray diffraction, IR spectroscopy, and Raman spectroscopy. The microstructure, tensile strength, and microporosity of fibers were investigated using SEM, tensile strength test, and microporosimeter. Although various MgO sources such as magnesium nitrate, acetate, and ethylate were used, the crystallization behavior of MgO-ZrO2 fibers at different temperatures could be summarized as follows: CubiclongrightarrowMetastable TetragonallongrightarrowMonocliniclongrightarrowCoexistence of Monoclinic and CubiclongrightarrowCubic(trace of monoclinic). At 150$0^{\circ}C$, the phase transformation of MgO-ZrO2 fibers shows the following change depending on the amount of MgO[Mg(NO3)2.6H2O]: At 10 mol%, both monoclinic and cubic phase coexist, at 12 mol%, monoclinic phase decreases rapidly, and then at 14 mol%, only cubic phase remains. When the MgO-ZrO2 fibers containing 12 mol% magnesium nitrate were heated at 80$0^{\circ}C$ for 1hr, average tensile strength of fibers is 4.0 GPa at diameters of 20 to 30 ${\mu}{\textrm}{m}$. As the heat-treatment temperatures increase to 100$0^{\circ}C$ for 1 hr, tensile strength of MgO-ZrO2 fibers decreases rapidly to 0.7 GPa.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4185-4190
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• 2013

We executed the property changes of the sintered MgO (99.9% purity, 300nm size) specimens with addition to CaO content of 0.00wt%, 0.25wt%, and 0.50wt%, processed at 7GPa, for 5min, 600~$800^{\circ}C$. To investigate the micro-structure and physical property changes of the sintered MgO(-CaO), we employed a scanning electron microscopy(SEM), X-ray diffractomerty(XRD), Vickers hardness, and density. The SEM result showed that MgO powder of 300nm size was changed into sintered structure of 520nm by high pressure and low temperature sintering, regardless of the CaO contents. According to the XRD analysis, no CaO phase observed, while MgO peaks shift indicated the existence of CaO in the MgO matrix. The Vickers hardness result showed that hardness of sintered MgO-CaO increased by 12% compared pure MgO under the same temperature conditions. It implied that we can obtain the same hardness with $100^{\circ}C$ lowered sintering temperatures by addition of CaO. The density results showed that it was possible to obtain density of 98%, which is 5% greater than that of pure MgO at low temperature of $600^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.40 no.11
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• pp.1132-1137
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• 2003

For the application of environment conscious glass-fertilizer, dissolution characteristics of phosphate glass was investigated. In 0.1K₂O-0.1SiO₂-0.6P₂O/sub 5/ glass system, the compositions were designed according to variation of CaO & MgO contents, and glass formation region was confirmed. From the glass composition, the confirmed glasses were investigated to figure out thermal and dissolution properties. It was detected that glass transition & softening temperature of the glasses increased with increasing MgO contents. The dissolution properties of the glasses was affected by CaO and MgO content ratio.

• Journal of Korea Foundry Society
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• v.27 no.3
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• pp.126-130
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• 2007

Oxidation behavior of CaO added Mg and Mg-5Al alloys was investigated. At $500^{\circ}C$, oxidation rate of pure Mg was abruptly increased, while that of CaO added Mg was remarkably reduced with increasing CaO content. As a result of surface analysis by AES, there was the thin oxide layer mixed with MgO and CaO in CaO added Mg. Oxidation behavior of CaO added Mg was similar to that of Ca added Mg. Oxidation rate of 0.6CaO added Mg-5Al alloy was much lower than that of Mg-5Al alloy at $500^{\circ}C$ and both alloys showed the linear weight change at $400^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.23 no.1
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• pp.51-59
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• 1986

It was the first time the MgO-C brick was developed for the lining materials in the hot spots in electric are furnace in 1972. MgO-C brick is high registant to thermal and structural spalling. Futhermore for the reason that carbon is hard to react with slag and MgO is high fireproof MgO-C brick shows a high corrosion registance to slag attack compared with conventional basic refractories. Owing to their excellent properties the use of MgO-C refractories are being developed widely in the field of shaped refractories and even in that of monolithic refractories. In this paper the oxidation of carbon the infiltration of slag into the brick texture and effects of additions were investigated. The results obtained were as follows : 1) The use of fused MgO-clinker and high purity carbon as raw materials increased the corosion registance and hot modulus of rupture of MgO-C brick. 2) As the oxidation reaction of the carbon proceeded the slag infiltrated into the brick texture. And then the slag components reacted with the MgO grains and formed low melting point compounds particulary CaO.MgO.$SiO_2$ and 3CaO.MgO.$2SiO_2$ that resulted in the wear of the brick. 3) It is recongnized the Al, Si, $B_3C$ effects on the oxidation registant properties of MgO-C brick by contribu-ting to the decrease of permeability according to the formation of $Al_4C_3$, SiC, $B_2O_3$ and the decrease of open pores relating to the formation of MgO.Al2O3, $SiO_2$, 3MgO.$B_2O_3$ at the decarbonized layer.

• Journal of the Korean Vacuum Society
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• v.8 no.1
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• pp.70-74
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• 1999

MgO-CaO protective layers with various composition were prepared by electron beam evaporation to improve the characteristics of conventional pure MgO thin films as a protective layer for AC-PDP. The maximum deposition rate of pure MgO was 1025 $\AA$/min and decreased with increasing [(CaO/(MgO+CaO)] ratio of evaporation starting materials. From XRD analyses, a trend of peak shift to the lower 2$\theta$ angle side was shown as CaO content increased and it stoped when the concentration of CaO was 0.13, which corresponds to the maximum solubility of CaO in MgO. The optimum composition of the protective thin films was Mg 47.1 at%, Ca 1.3 at%, O 51.6 at%, and firing voltage, memory margin and deposition rate of the film with this composition was 176 V, 0.5 and 515 $\AA$/min, respectively.

• Korean Journal of Crystallography
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• v.13 no.2
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• pp.57-62
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• 2002

Time-of-flight impact-collision ion scattering spectroscopy (TOF-ICISS) was applied to study the geometrical structure of epitaxially grown TiO layers on a MgO(001) surface. The hetero-epitaxial TiO layer was deposited by thermal evaporation of titanium onto the MgO(001) surface and subsequent exposure to oxygen at 400℃. The well-ordered TiO structure was confirmed with the 1×1 RHEED pattern. TOF-ICISS results revealed that the TiO layer was formed at the on-top sites of the MgO(001) substrate and that the lateral lattice constant of TiO layer was the same as that of the MgO substrate. The surface of the deposited epitaxial TiO layer was smooth without the three dimensional islands.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.178-178
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• 2007

II-VI의 넓은 밴드갭 (3.37 eV)을 가지는 ZnO는 solar cells, transparent conductive electrodes, ultraviolet light emitters, and chemical sensors 등에 응용되고 있다. 특히 고효율 ZnO계 발광 소자 구현을 위하여 MgO (7.7eV), CdO (2.0eV) 등의 고용을 통한 밴드갭을 엔지니어링 하며, 단파장 영역의 광원을 확보하기 위하여 MgO 첨가를 통한 밴드갭 에너지를 증가시키는 방향으로의 연구가 활발하다. 그러나 ZnO의 wurtzite 구조와 MgO의 rocksalt 구조의 상이한 결정구조로 인하여 Mg의 고용한계는 4 at. %, 4.1 eV 알려져 있다. 본 실험에서는 p-type Si (100), c-sapphire (0002)과 GaN 기판 위에 MgO (99.999 %)와 ZnO (99.999 %) 두가지 타겟을 사용하여 RF co-스퍼터링법으로 ZnMgO 박막을 증착 하였다. 이때 ZnO 타겟의 power 밀도는 고정 시키고 MgO 타겟의 power 밀도를 변화 시키며 Mg의 함량을 조절하여 그에 따른 광학적 구조적 특성의 변화를 연구 하였다. 성장된 ZnMgO 박막은 MgO 타겟의 power 밀도가 증가할 때 Mg의 함량이 10 at. %까지 증가 하며, 그에 따른 표면의 거칠기 및 입계 크기가 감소하며, 박막의 성장속도 또한 감소함을 SEM과 AFM을 통하여 알 수 있었다. XRD를 동하여 ZnMgO 박막의 (0002) peak의 위치는 $34.50^{\circ}{\sim}34.7^{\circ}$로 오른쪽으로 이동하며, c-축으로 성장하였음을 알 수 있다. PL과 UV룰 동하여, Mg의 함량이 증가 할수록 박막의 밴드갭 에너지는 3.2 eV에서 4.1 eV 로 증가하였다.

• Journal of the Korean Ceramic Society
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• v.34 no.1
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• pp.31-36
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• 1997

The effects of 0 to 10mol% excess MgO addition on the microstructure and dielectric properties in 30Pb(Mg1/3Nb2/3)O3-20PbTiO3-50Pb(Mg1/2W1/2)O3 ternary system were investigated. Samples were prepared by mixed oxide and precursor methods to compare the role of excess MgO. Excess MgO enhanced grain growth and increased dielectric constant. The dielectric constant and tesmperature dependence of dielectric constant of the sample sintered at 100$0^{\circ}C$ with 5mol% MgO were above 5,000 and +25% to -50% from - 55$^{\circ}C$ to 1$25^{\circ}C$, respectively. For these specimens the phases percent were mainly perovskite and Pb2WO5, which was confirmed by XRD analysis. Also the amount of cubic pyrochlore Pb3Nb4O13 and PbWO4 were de-creased with sintering temperature and MgO addition. BSE image showed the chemical inhomogeneous dis-tribution. Crystal phase formed at each sintering temperature and the chemical inhomogeneous distribution caused the decrease of the temperature dependence of dielectric constant.