• Korean Journal of Crystallography
• /
• v.8 no.2
• /
• pp.149-153
• /
• 1997

ZnO varistor based on ZnO-Bi2O3-Co3O4-MnCO3-Cr2-O3-Sb2O3 system with Sb2O3 contents were studied for grain size variation and microstructure properties. The composition of pure ZnO varistor was observed composition was inhibited owing to formation of Zn7Sb2O12 spinel phase and did not observed abnrmal grain growth. With Sb2O3 contents, the grain sizes of ZnO varistor were remarkably decreased and the microstructure had the distribution of dense and homogeneous grains.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.14 no.1
• /
• pp.5-14
• /
• 1977

"Electrical Properties of Barium Titanates with Addition Sb2O3." PTC BaTiO3 in low resistance at room temperature was prepatred. Al2O3, SiO2 and TiO2 were doped with a view to improving reproduction. Sb2O3 was doped as impurity in order to control of resistivity of the specimens. The relations between the amount of Sb3O3 and electrical properties wereinvestigated. Of the compositions studied, additions of 3.75mole% Al2O3, 1.25mole% SiO2, 2.25mole% TiO2 and 0.16~0.25wt% Sb2O3 to BaTiC3 was low resistivity in 14-300 ohm-cm.00 ohm-cm.

• Journal of the Korean Ceramic Society
• /
• v.30 no.11
• /
• pp.955-961
• /
• 1993

Sintering behavior and microstructure development in the system ZnO-Bi2O3-CoO-Zn7Sb2O12 with Zn7Sb2O12 content(0.1mol%~2mol%) were studied. The pyrochlore phase was formed by the reaction of the Zn7Sb2O12 with Bi2O3 phase during heating (below 90$0^{\circ}C$). The formation temperature of the liquid phase (Bi2O3) was dependent on the Zn7Sb2O12 contents (about 74$0^{\circ}C$ for Bi2O3/Zn7Sb2O12>1 by the eutectic melting in the ZnOBi2O3 system, and about 110$0^{\circ}C$ for Bi2O3/Zn7Sb2O12 1 by the decomposition of pyrochlore phase). Hence, sintering behavior and microstructure development were determined virtually by the Bi2O3/Zn7Sb2O12 ratio, which were promoted by liquid (Bi2O3) phase and retarded by the pyrochlore (or spinel) phase. The grain growth of ZnO during sintering was sluggish with increasing Zn7Sb2O12 contents.

• Journal of the Korean Ceramic Society
• /
• v.31 no.11
• /
• pp.1396-1400
• /
• 1994

Electrical properties in the ZnO-Bi2O3-CoO-Zn7Sb2O12 system were investigated with Zn7Sb2O12 content (0.1~2 mol%). The increase of the Zn7Sb2O12 content inhibited the grain growth of ZnO, which showed a narrow grain size distribution of ZnO. The breakdown voltage (Vb) increased markedly with 1 mol% Zn7Sb2O12 addition due to the grain growth control behaviour of the Zn7Sb2O12 . The nonlinear I-V characteristic was significantly influenced by the Zn7Sb2O12 content (or Bi2O3/Zn7Sb2O12 ratio). Addition of 0.5 mol% Zn7Sb2O12 showed the highest nonlinear coefficient ($\alpha$) of 43. The leakage current in prebreakdown region was decreased with increasing Zn7Sb2O12 content.

• Journal of the Korean Ceramic Society
• /
• v.37 no.2
• /
• pp.186-193
• /
• 2000

Effects of 1.0 mol% CoO addition on sintering and the electrical properties of ZnO-Bi2O3-Sb2O3(ZBS) varistor system with 3.0 mol% co-addition of Sb2O3 and Bi2O3 at various Sb/Bi ratio (0.5, 1.0, and 2.0) were investigated. Cobalt had little influence on the liquid-phase formation and the pyrochlore decomposition temepratures of ZBS, while densification was mainly dependent on Sb/Bi ratio: when Sb/Bi=0.5, excess Bi2O3 irrelevant to the formation of pyrochore(Zn2Sb3Bi3O14) forms eutectic liquid at ~75$0^{\circ}C$ which promotes densification and grain growth; with Sb/Bi=2.0, the second phase Zn7Sb2O12 formed by excess Sb2O3 irrelevant to the formation of the pyrochlore retards densification up to ~100$0^{\circ}C$. These phases caused the coarsening and uneven distribution of the second phase particles on the grain boundaries of ZnO above the pyrochlore decomposition temperature(~105$0^{\circ}C$), which led to broad size dist-ribution of ZnO; the specimen with Sb/Bi=1.0 showed homogeneous microstructure compared with the others, which enabled improved varistor characteristics. Doping of Co increased the nonlinearity and the potential barrier height of ZBS, which is thought to stem from improved sintering behavior such as homogenized microstructure due to size reduction and even distribution of the second phase and suppressed volatility of Bi2O3, as well as the improvement in the potential barrier structure via increased donor and interface electron trap densities.

• Journal of the Korean Ceramic Society
• /
• v.29 no.2
• /
• pp.101-106
• /
• 1992

Sintering behavior, distribution of dopant oxides and electrical properties in the ZnO-Bi2O3-CoO-Sb2O3 and ZnO-Bi2O3-CoO-Sb2O3-Cr2O3 systems were studied. The linear shrinkage of ZnO varistors from 850 to 950$^{\circ}C$ was related to the decomposition reaction (py\longrightarrowsp+Bi2O3) of the pyrochlore phase. In the distribution of the dopant oxides (CoO, Sb2O3, Cr2O3), Co distribute uniformly throughout the sample, the distribution of Sb coincided with small particles (spinel phase, Zn7Sb2O12), and Cr distributed very consistently with Sb. The increase in breakdown voltage, due to the addition of Cr2O3, was not only attributed to the decrease in the ZnO grain size but also to the solution of Cr2O3 in the spinel phase. The leakage current (80% V60 ${\mu}\textrm{A}$) was increased by the addition of Cr2O3.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.07a
• /
• pp.369-372
• /
• 2000

ZnO varistor is studied to sintering condition and mixing condition for the improvement to non linear of electrical characteristics. In this paper, ZnO varistor, ZnO-Bi$_2$O$_3$-Y$_2$O$_3$-MnO-Cr$_2$O$_3$-Sb$_2$O$_3$series, is fabricated with Sb$_2$O$_3$mol ratio(0.5~4[mol%]) and sintered at 1250[$^{\circ}C$] for 2 hours. The grain size to Sb$_2$O$_3$moi ratio was measured by fractal mathematics. The ZnO varistors that Sb$_2$O$_3$mot ratio is 1[mol%] were shown small grain size because of spinel phase. The fractal dimension were increased with increasing of Sb$_2$O$_3$mo ratios. The capacitance of ZnO varistors with increasing of Sb$_2$O$_3$additive in voltage-capacitance characteristics was decreased by small grain size.

• Korean Journal of Materials Research
• /
• v.1 no.2
• /
• pp.65-70
• /
• 1991

The effect of inclusion particles on the microstructure development and electrical characteristics in the systems $ZnO-Bi_2O_3-CoO-Sb_2O_3\;and\;ZnO-Bi_2O_3-CoO-Sb_2O_3-Cr_2O_3 were investigated. The growth of ZnO grains, which was controlled by the spinel particles during sintering, decreased with increasing amount of spinel particles. Addition of $Cr_2O_3(0.5mol\%) increased the breakdown voltage without affecting the non-linear characteristics. The calculated barrier voltage of the $ZnO-Bi_2O_3-CoO-Sb_2O_3\;-and\;ZnO-Bi_2O_3-CoO-Sb_2O_3-Cr_2O_3$ systems were about 3.1V and 2.9V, respectively.

• Fibers and Polymers
• /
• v.1 no.1
• /
• pp.6-11
• /
• 2000

In the polycondensation reaction of polyethyleneterephthalate(PET), $Sb_2$$O_3$, can react effectively as a catalyst, if physically transformed. $Sb_2$$O_3$ powder is transformed into liquid solution by dissolving in ethylene glycol(EG). Homogeneous catalyst is made by mixing this liquid solution with glycols having different solubility. The efficient reaction of PET polymerization is expected by using homogeneous catalyst. PET was synthesized using homogeneous catalysts of 4 wt.% $Sb_2$$O_3$ solution dissolved in glycol[EG, 2,2-bis(4-(2-hydroxyethoxy)phenol)propane(BHPP), neopentyl glycol(NPO), and 1,3-propandiol(PD)]. PET using EG-BHPP($Sb_2$$O_3$) catalysts shows the highest I.V. within a reaction time of 120 min. In the p-d analysis, PET using EG-BHPP($Sb_2$$O_3$) catalysts has the fastest propagation rate and slowest degradation rate. EG-BHPP($Sb_2$$O_3$) catalysts are more efficient than EG($Sb_2$$O_3$) catalysts and $Sb_2$$O_3$ powder catalysts.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.24 no.12
• /
• pp.969-976
• /
• 2011

In this study we aims to evaluate the effects of 1/3 mol% $Co_3O_4$ addition on the reaction, microstructure development, resultant electrical properties, and especially the bulk trap and grain boundary properties of $ZnO-Bi_2O_3-Sb_2O_3$ (Sb/Bi=2.0, 1.0, and 0.5) system (ZBS). The samples were prepared by conventional ceramic process, and characterized by XRD, density, SEM, I-V, impedance and modulus spectroscopy (IS & MS) measurement. In addition of $Co_3O_4$ in $ZnO-Bi_2O_3-Sb_2O_3$ (ZBSCo), the phase development, density, and microstructure were controlled by Sb/Bi ratio. Pyrochlore on cooling was reproduced in all systems. The more homogeneous microstructure was obtained in ZBSCo (Sb/Bi=1.0) system. In ZBSCo, the varistor characteristics were improved drastically (non-linear coefficient ${\alpha}$=23~50) compared to ZBS. Doping of $Co_3O_4$ to ZBS seemed to form $V^{\cdot}_o$(0.33 eV) as dominant defect. From IS & MS, especially the grain boundary of Sb/Bi=0.5 system is composed of electrically single barrier (0.93 eV) and somewhat sensitive to ambient oxygen with temperature.