It is an object of the present invention to provide a raw material powder
for stably obtaining a dense sinter that is prevented from cracking, and
a method for manufacturing this powder, and a method for manufacturing a
lanthanum-based oxide ion conductor in which this raw material powder is
used.The raw material powder manufacturing method of the present
invention is a method for manufacturing a raw material powder for forming
an oxide ion conductor composed of a multi-component metal oxide
including lanthanum or lanthanide, wherein a mixed powder blended such
that all of the elements constituting said multi-component metal oxide
are included is prefired, after which this prefired powder is exposed to
water or moist gas so as to expand at least some of the particles in said
powder. Alternatively, two types of mixed powder with different
components are prefired separately, after which the prefired powders are
blended in a specific ratio.