• The Korean Journal of Ceramics
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• 제5권2호
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• pp.165-170
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• 1999

The strain sensing properties of th system xNiO-(1-x) CaO with various compositions (x=0.001-0.05) are evaluated and the origin of the phenomena is guessed. We have found out that the high temperature electrical conductivity of the xNiO-(1-x)CaO increases by applying the compressive stress at $1000^{\circ}C$. When the applied load is removed, the electrical conductivity rapidly decreases and returns to the original value, but a small hysteresis of the stress-conductivity curve is observed. After the loading test, the lattice parameter of the specimen is found lengthened. The correlation between the lengthening of the lattice parameter and the increases in the electrical conductivity by loading is discussed. The amount of the "expanded type" Ni(II)O6 clusters in the xNiO-(1-x)CaO grains is supposed to be increased by the applied stress, which would be the origin of the strain dependent electric conduction in the xNiO-(1-x)CaO system.aO system.

• 한국자기학회지
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• 제13권6호
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• pp.246-250
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• 2003

고주파 대역에서 전자기적 특성이 안정적으로 유지되는 Ni-Zn 페라이트를 제조하기 위해 Ni$_{0.8}$Zn$_{0.2}$Fe$_2$O$_4$를 기본조성으로 Bi$_2$O$_3$와 CaO를 첨가하였다. Bi$_2$O$_3$의 첨가량이 0.3 wt%까지는 손실이 증가하였고 그 이상의 첨가량에서는 감소하였으며, 투자율은 Bi$_2$O$_3$ 첨가량이 증가할수록 증가하였다. Bi$_2$O$_3$와 CaO는 고용체를 형성하여 입계에 편석 됨으로서 비저항층을 형성하여 각각 0.7 wt%, CaO 0.3 wt% 첨가할 경우 가장 낮은 손실과 높은 공명주파수를 나타내었다.

• 한국재료학회지
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• 제28권5호
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• pp.273-278
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• 2018

Lithium-ion batteries have been considered the most important devices to power mobile or small-sized devices due to their high energy density. $LixCoO_2$ has been studied as a cathode material for the Li-ion battery. However, the limitation of its capacity impedes the development of high capacity cathode materials with Ni, Mn, etc. in them. The substitution of Mn and Ni for Co leads to the formation of solid solution phase $LiNi_xMn_yCo_{1-x-y}O_2$ (NMC, both x and y < 1), which shows better battery performance than unsubstituted $LiCoO_2$. However, despite a high discharge capacity in the Ni-rich compound (Ni > 0.8 in the metal site), poor cycle retention capability still remains to be overcome. In this study, aiming to improve the stability of the physical and chemical bonding, we investigate the stabilization effect of Ca in the Ni-rich layered compound $Li(Ni_{0.83}Co_{0.12}Mn_{0.05})O_2$, and then Ca is added to the modified secondary particles to lower the degree of cationic mixing of the final particles. For the optimization of the final grains added with Ca, the Ca content (x = 0, 2.5, 5.0, 10.0 at.%) versus Li is analyzed.

• 한국전기전자재료학회논문지
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• 제21권7호
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• pp.645-651
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• 2008

To reduce noise in high frequency and distortion of signal, the composition of $(Ca_{0.7}Sr_{0.3})(Zr_{0.97}Ti_{0.03})O_3$ and $(Ba_{0.2}Ca_{0.4}Sr_{0.4})TiO_3$ was developed. The composition was not solid solution, but mixtures of various phases composed of Ca, Sr, Zr, Ti and Ba oxides. The dielectric constant increased, the quality factor and the insulation resistance decreased with $(Ba_{0.2}Ca_{0.4}Sr_{0.4})TiO_3$ content. The composition of $0.4(Ba_{0.2}Ca_{0.4}Sr_{0.4})TiO_3$ satisfied the electric characteristics and the temperature coefficient of dielectric constant (TCC). In addition, the glass frit and $MnO_2$ also affected the electric characteristics. From the result of the best fit simulation, $MnO_2$ 0.3 mol%, the glass frit 0.6 wt% showed the insulation resistance $906{\Omega}{\cdot}F$, the quality factor 821, and the dielectric constant 92. With the selected composition, MLCC capacitors sized $4.5{\times}3.2{\times}2.5mm$ were manufactured with 105 layered of the dielectric thickness $16{\mu}m$ using Ni inner electrode, They represented the capacitance $98{\sim}102$ nF, the quality factor 1,200 and the insulation resistance $1,500{\Omega}{\cdot}F$. Also, they had high break-down voltage with $107{\sim}115V/{\mu}m$, and satisfied the SL TCC characteristics.