GROWTH-RATE OF YTTRIA-STABILIZED ZIRCONIA THIN-FILMS FORMED BY ELECTROCHEMICAL VAPOR-DEPOSITION USING NIO AS AN OXYGEN SOURCE - II - EFFECTOF THE POROSITY OF NIO SUBSTRATE
M. Inaba et al., GROWTH-RATE OF YTTRIA-STABILIZED ZIRCONIA THIN-FILMS FORMED BY ELECTROCHEMICAL VAPOR-DEPOSITION USING NIO AS AN OXYGEN SOURCE - II - EFFECTOF THE POROSITY OF NIO SUBSTRATE, Solid state ionics, 104(3-4), 1997, pp. 303-310
Yttria-stabilized zirconia (YSZ) thin films were formed at 1000 degree
s C by a modified electrochemical vapour-deposition (EVD) using NiO as
an oxygen source, and ZrCl4 and YCl3 as metal sources. Growth rate ki
netics were examined using NiO pellet substrates with different pore s
tructures. The thickness of YSZ film increased linearly with depositio
n time, and the growth rate increased with increasing the porosity of
the substrate. The pore size as well as the porosity affected the grow
th rate. In addition, the observed growth rate was much slower than th
e theoretical one assuming that the electrochemical transportation of
the charged species across the growing film is rate limiting. From the
se results, it was concluded that the rate-determining step is not the
bulk electrochemical transport, but the mass transport of dissociated
oxygen in the substrate pore.