• Korean Journal of Materials Research
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• v.9 no.7
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• pp.753-759
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• 1999

The microstructure and electrical properties of ZNR that W $O_3$ is added in the range 0.5~4.0mol%, were investigated. The major part of W $O_3$ were segregated at the nodal point and W-rich phase was formed. Three crystalline phases, such as W-rich phase (W $O_3$), Bi-rich phase (B $i_2$W $O_{6}$ ), and spinel phase (Z $n_{2.33}$S $b_{0.67}$ $O_4$) were confirmed to be co-existed at the nodal point The average grain size increased in the range 15.5~29.9$\mu\textrm{m}$ with increasing W $O_3$ additive content. Consequently. W $O_3$ acted as a promotion additive of grain growth. As the W $O_3$ additive content increases. the varistor voltage and the nonlinear exponent decreased in the range 186.82~35.87V/mm and 20.90~3.34, respectively, and the leakage current increased in the range of 22.39~83.01 uh. With increasing W $O_3$ additive content, the barrier height and the density of interface states decreased in the range 1.93~0.43eV and (4.38~1.22)$\times$10$^{12}$ $\textrm{cm}^2$, respectively. W $O_3$ acted as an acceptor additive due to the donor concentration increasing in the range (1.06~0.38)$\times$10$^{18}$ /㎤with increasing W $O_3$ additive content.t.t.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.2 s.35
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• pp.161-166
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• 2005

Glass formation, thermal property and crystallization behavior were investigated in $xK_2O-(33.3-x)BaO-16.7TiO_2-50SiO_2(mole\%)$ with fresnoite($Ba_2TiSi_2O_8$) crystal by replacement BaO for $K_2O$. As x(0$\le$x$\le$20) contents increased, glass formation became easy, and crystallization temperature moved on to the low temperature. Crystal phase of the $Ba_2TiSi_2O_8$ was confirmed by XRD, and the replaced x was not effected on the formation of new crystals. The kinetics of crystallization of fresnoite were studied by applying the DTA measurements carried out at different heating rates. The average avrami exponent(n) and activation energy were changed $2.26 {\pm}0.1,\;2.03 {\pm}0.1,\;1.93{\pm}0.15$, $279 {\pm}12kJ/mole,\;302{\pm}7kJ/ mole,\;319{\pm}1kJ/mole$ according to x contents, respectively. The replaced x improved the orientation of crystal growth.