Formation Mechanism of Intermediate Phase in <TEX>$Ba(Mg_{1/3}Ta_{2/3})O_3$</TEX> Microwave Dielectrics

Fang, Yonghan; Oh, Young-Jei; Fang, Yonghan; Oh, Young-Jei

J. Korean Ceram. Soc. > Volume 38(10); 2001 > Article

Journal of the Korean Ceramic Society 2001;38(10): 881.

Formation Mechanism of Intermediate Phase in $Ba(Mg_{1/3}Ta_{2/3})O_3$ Microwave Dielectrics

Materials Science & Technology Division, Cheongryang, Korea Institute of Science and Technology
¹Department of Inorganic Materials, Shanghai University

ABSTRACT

Kinetics and mechanisms of intermediate phases formation in $Ba(Mg_{1/3}Ta_{2/3})O_3$, obtained by a solid state reaction were studied. $Ba{Ta_2}{O_6}$ and ${Ba_4}{Ta_2}{O_9}$ as intermediate products were first formed at $700^{circ}C$. $Ba(Mg_{1/3}Ta_{2/3})O_3$ was appeared at $800^{circ}C$. Several reactions take place on heating process. $Ba{Ta_2}{O_6}$ is found at the first stage of the reaction, and then $Ba{Ta_2}{O_6}$ or ${Ba_4}{Ta_2}{O_9}$ react with MgO to form $Ba(Mg_{1/3}Ta_{2/3})O_3$. The reaction of $Ba(Mg_{1/3}Ta_{2/3})O_3$ formation does not complete until fired at $1350^{circ}C$ for 60 min. The kinetics of solid-state reaction between powdered reactants was controlled by diffusion mechanism, and can be explained by the Jander's model for three-dimensional diffusion.

Key words: $Ba(Mg_{1/3}Ta_{2/3})O_3$, $Ba{Ta_2}{O_6}$, ${Ba_4}{Ta_2}{O_9}$, Intermediate phase, Kinetics, Diffusion mechanism, Jander's model