Hj. Schmutzler et al., A NOVEL REACTION-PATH TO BATIO3 BY THE OXIDATION OF A SOLID METALLIC PRECURSOR, Journal of the American Ceramic Society, 77(3), 1994, pp. 721-729
Multilayer capacitors with thin, dielectric BaTiO3 layers can possess
a relatively high capacitance per unit volume. A solid metallic precur
sor method has recently been developed for preparing thin BaTiO3/noble
metal laminates. In the present paper, the phase and microstructural
evolution of Ba-Ti metallic precursors were examined after oxidation a
t 300-degrees to 900-degrees-C in pure oxygen at 1 atm pressure. Bariu
m peroxide, BaO2, formed rapidly during oxidation at 300-degrees-C, wi
th titanium largely remaining as unoxidized particles in the peroxide
matrix. Between 375-degrees and 500-degrees-C, the solid-state reactio
n of barium peroxide with metallic titanium yielded barium orthotitana
te, Ba2TiO4. Further exposure to temperatures between 500-degrees and
900-degrees-C resulted in the oxidation of residual metallic titanium.
The oxidized titanium then reacted with the orthotitanate matrix to f
orm barium metatitanate, BaTiO3. The rate of formation of BaTiO3 was f
ound to be strongly dependent on the degree of milling of the Ba-Ti pr
ecursors and on the heating rate between 300-degrees and 500-degrees-C
.