Addition of 0.5 mol% of CoO into SnO2 promotes densification of this oxide
to 99% of the theoretical density during sintering. TEM in this system reve
als that after sintering at 1210 degrees C a secondary phase of Co2SnO4 is
precipitated at the SnO2 grain boundaries during cooling. This phase is for
med by diffusion of Co ions from the bulk to the grain boundary during sint
ering leaving needle-like defects at the grain bulk. The high resolution TE
M micrograph of this system sintered at 1210 degrees C and 1400 degrees C s
howed an amorphous grain boundary region low in cobalt, indicating that the
Co2SnO4 phase is precipitated from this region. (C) 1999 Elsevier Science
Limited and Techna S.r.l. All rights reserved.