Preparation and Electrical Conductivity of <TEX>$beta$</TEX>-<TEX>$Al_2O_3$</TEX>

,; ,; ,; ,; ,; ,

J. Korean Ceram. Soc. > Volume 23(3); 1986 > Article

Journal of the Korean Ceramic Society 1986;23(3): 1.

$beta$-$Al_2O_3$의 제조 및 전기전도도

송효일, 김응수, 윤기현

연세대학교 공과대학 요업공학과

Preparation and Electrical Conductivity of $beta$-$Al_2O_3$

ABSTRACT

The preparation and electrical conductivity of $beta$-$Al_2O_3$ are investigated as a function of $Na_2O$ content from the-oretical composition of $beta$-$Al_2O_3$ to that of $beta$"-$Al_2O_3$. $beta$-$Al_2O_3$ $beta$"$Al_2O_3$$alpha$-Al2O3 and ${gamma}$-NaAlO2 phases appear in the calcined powder at 125$0^{circ}C$ for 2 hours. The majoity phase is $beta$-$Al_2O_3$ in sintered specimens at 155$0^{circ}C$ and 1$650^{circ}C$ for 30 mins respectively and ${gamma}$-4NaAlO_2$ phase also exists when Na2O content is over 10.39w/o ${gamma}$-4NaAlO_2$ phase does not affect the grain growth of $beta$-$Al_2O_3$ in sintering at 155$0^{circ}C$ but acts as a reactive liquid for the abnormal grain growth of $beta$-$Al_2O_3$in sintering at 1$650^{circ}C$ The electrical conduction of $beta$-$Al_2O_3$is predominated by 4Na^+$ ion. Contribution of ionic con-ductivity to total conductivity is gradually decreased with increasing temperature at given oxygen pressure and to -tal conductivity is increased by positive hole due to interstitial oxygen with increasing oxygen pressure.