• 한국세라믹학회지
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• 제53권2호
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• pp.139-144
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• 2016

The dependence of the microwave dielectric properties of the glass-ceramic composite $0.9CaMgSi_2O_6-0.1MgSiO_3$ on the crystallization behaviour was investigated as functions of the $TiO_2$ content and heat-treatment temperature. The crystallization behaviour of the specimens was evaluated via a combination of the Rietveld and reference-intensity ratio methods. For specimens with a $TiO_2$ content of up to 1 wt.%, a monoclinic diopside phase was formed, whereas a secondary $TiO_2$ phase was formed with further increases in the $TiO_2$ content. The quality factor (Qf) of the specimens was strongly dependent on the degree of crystallization. The highest Qf value was obtained with a $TiO_2$ content of 0.5 wt.%, which was improved by increasing the heat-treatment temperature. The dielectric constant (K) was affected by the size of the crystallites and the $TiO_2$ content. The temperature coefficient of the resonant frequency (TCF) was nearly constant for all of the specimens, regardless of the $TiO_2$ content or heattreatment temperature.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 춘계학술대회 논문집 디스플레이 광소자 분야
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• pp.148-151
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• 2000

$Mg_{2-2x}Ti_xO_2$ films were prepared by e-beam evaporation method to be used as possible substitutes for the conventional MgO protective layer. The oxygen content in the films and in turn, the ratio of metal to oxygen gradually increased with increasing the $TiO_2$ content in the starting materials. The pure MgO films exhibited the crystallinity with strong (111) orientation. The $Mg_{2-2x}Ti_xO_2$ films, however, had the crystallinity with (311) preferred orientation. When the $[TiO_2/(MgO+TiO_2)]$ ratios of 0.1 and 0.15 were used, the deposited films exhibited the secondary electron emission yields improved by 50% compared to that of the conventional MgO protective layer, which resulted in reduction in discharge voltage by 12%.

• 한국세라믹학회지
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• 제54권2호
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• pp.141-149
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• 2017

The influence of the co-additive concentration (0 - 45 wt% with an interval of 5 wt%) of MgO-$TiO_2$ on the phase formation, microstructure and fracture toughness of MgO-$TiO_2$-reinforced dental porcelain nanocomposites derived from a one-step sintering technique were examined using a combination of X-ray diffraction, scanning electron microscopy and Vickers indentation. It was found that MgO-$TiO_2$-reinforced dental porcelain nanocomposites exhibited significantly higher fracture toughness values than those observed in single-additive (MgO or $TiO_2$)-reinforced dental porcelain composites at any given sintering temperature. The amount of MgO-$TiO_2$ as a co-additive was found to be one of the key factors controlling the phase formation, microstructure and fracture toughness of these nanocomposites. It is likely that 30 wt% of MgO-$TiO_2$ as a co-additive is the optimal amount for $MgTi_2O_5$ and $Mg_2SiO_4$ crystalline phase formation to obtain the maximum relative density (96.80%) and fracture toughness ($2.60{\pm}0.07MPa{\cdot}m^{1/2}$) at a sintering temperature of $1000^{\circ}C$.

• 한국세라믹학회지
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• 제46권2호
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• pp.189-199
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• 2009

The Powder characteristics and sintering behavior of $SiO_2$ coated $BaTiO_3$ were studied. $BaTiO_3$ powders were synthesized by the liquid mix method developed by Pechini, and silica coating was prepared by alkoxide hydrolysis method with TEOS and ethanol. The particle size of the $BaTiO_3$ powders was 35 nm and the thickness of the $SiO_2$ coating layer was 5 nm. As the $SiO_2$ content increased, the $SiO_2$ layers improved the powder dispersion by increasing electrostatic repulsion between the $BaTiO_3$ particles. Effects of MgO coating on microstructure and dielectric properties of $BaTiO_3$ have been studied compared with mechanically MgO mixed $BaTiO_3$. MgO coated $BaTiO_3$ particles were prepared by a homogeneous precipitation method using $MgCl_2\cdot 6H_2O$ and urea. MgO coated $BaTiO_3$ exhibited homogeneous microstructure compared with mixed samples. XRD analysis revealed that Mg substitution for the Ti site in the MgO mixed sample was much greater than in the coated one. Electrical properties of MgO mixed and coated $BaTiO_3$ were affected by the diffusion behavior of Mg in $BaTiO_3$ lattice.

• 한국세라믹학회지
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• 제26권2호
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• pp.249-257
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• 1989

Dielectric properties and the stability of the perovskite phase in the Pb(Mg1/3Nb2/3)O3 system have been investigated as a function of amount of BaTiO3 and firing temperature. In the specimens fired at 120$0^{\circ}C$, the pyrochlore phase was eliminated by the addition of 10-15m/o BaTiO3 and also the dielectric constant increased. However, the dielectric constant decreased with further addition of BaTiO3 even though no pyrochlore phase was found to be present. The reducing tendency of the pyrochlore phase decreased with lowering the firing temperature in the system of Pb(Mg1/3Nb2/3)O3 with BaTiO3. Dielectric properties in PMN ceramics were affected by the character of the BaTiO3 rather than the pyrochlore phase.

• 대한전기학회논문지
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• 제45권2호
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• pp.235-241
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• 1996

In this paper dielectric and electrostrictive strain properties of (1-y-x)Pb(Mg$_{1/3}$Nb$_{2/3}$)O$_{3}$-PbTiO$_{3}$$-yPbTiO_{3}-xSrTiO_{3}[(1-y-x)PMN-yPT-xST]$ ceramics fabricated by using columbite precursor method have been investigated with the substitution of SrTiO$_{3}$(ST). Dielectric constant of the specimens increased with the increase of ST content up to 5[m/o] and decreased with further substitution of ST. And the pyrochlore phase decreased with the increase of ST content up to 5[m/o] in XRD analysis. The elimination of the pyrochlore phase improved dielectric constants. The electrostrictive strains generated by AC electric field have the highest value at 5[m/o] SrTiO$_{3}$ addition and the hysteresis of strain ranged from 12 to 20[%]. The electrostrictive strain at various temperature investigated in the temperature range of $-50[^{\circ}C]~74[^{\circ}C].$ In higher temperature than phase transition region, it showed paraelectric property which shows very small hystersis.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1992년도 춘계학술발표회
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• pp.89-90
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• 1992

• 한국진공학회지
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• 제10권2호
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• pp.234-240
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• 2001

본 연구에서는 Mg을 첨가한 Cu-alloy에 의해 TiN의 확산방지능력을 향상시키고자 하였다. Cu(Mg) 박막은 대기노출시킨 TiN박막위에 증착되었으며 열처리시 Cu 박막내의 Mg은 TiN의 표면에 있는 산소와 반응하여 매우 얇은(~100 $\AA$) MgO를 형성하게되고 MgO에 의해 TiN의 확산방지능력은 Cu(4.5 at.%Mg)의 경우 $800^{\circ}C$까지 향상됨을 알 수 있었다. 그러나 Cu(Mg) a]toy는 TiN위에서 접착특성이 좋지 않기 때문에 TiN을 $O_2$plasma 처리하였으며 $O_2$ plasma 처리후 $300^{\circ}C$ 진공열처리를 통해 접착력이 크게 향상되는 것을 알 수 있었다. 이는 $O_2$ plasma 처리에 의해 TiN표면에 Mg과 반응할 수 있는 산소의 양이 증가하는 데 기인하며 이에 따라 Mg의 계면이동이 크게 증가되어 치밀한 MgO가 형성됨을 확인하였다. 그리고 $O_2$ plasma 처리시 RF power를 증가시키면 계면으로 이동하는 Mg의 양이 오히려 감소하였고 이것은 TiN의 표면이 $TiO_2$로 변하여 Mg과 결합할 수 있는 산소의 양이 상대적으로 감소하였기 때문인 것으로 생각된다. 또한 접착층으로서 Si을 50$\AA$ 증착하여 접착력을 크게 향상시켰으며 Si 증착에 의한 TiN의 확산방지능력은 감소되지 않는 것을 알 수 있었다.

• 전자공학회논문지T
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• 제36T권3호
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• pp.7-12
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• 1999

본 논문은 (1-x-y)PMN-yPT-xST세라믹스의 유전 및 변위특성을 ST의 양에 따라 조사하였다. ST의 성분은 1∼ 6㏖%이내로 변화시켰고 과잉 MgO에 따른 조성변화에 따라 결과를 조사하였다. ST의 성분의 증가에 따라 유전상수는 5㏖%인 조성에서 최대값을 나타내었다. 큐리온도는 ST의 성분이 증가함에 따라 선형적으로 감소하였다. 항전계와 잔류분극은 l㏖%인 조성에서 최대값을 나타내었다. 과잉 MgO의 효과에 따라 유전상수는 0.8PMN-0.12PT-0.04ST조성에서 MgO를 3㏖%까지 과잉 첨가함에 따라 증가하였으나 변위특성은 감소함을 나타내었다.

• 자원리싸이클링
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• 제30권2호
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• pp.46-52
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• 2021

타이타늄의 제련 및 가공 공정에서 산소 농도가 높은 off-grade 스크랩이 발생되고 있다. 본 연구에서 이러한 off-grade Ti 스크랩을 혼합 염화물을 플럭스로 사용하여 Mg으로 탈산하였다. 실험은 α-Ti 영역(1,023~1,123 K)에서 실시하였으며, 반응 시간, 반응 온도, Mg양, 염화물 비율의 영향에 대하여 조사하였다. 플럭스로 사용된 YCl3가 MgO와 반응하여 αMgO의 활동도를 낮추어 Mg에 의한 Ti의 탈산이 가능하였으며, 1,073 K, 6시간 조건에서 Mg=3.6 g, $X_{YCl_3}=0.22$ 일때 Ti scrap의 산소 농도가 0.5 %에서 최저 농도인 0.1117 %까지 감소하였다.