TY - JOUR
T1 - Constraint of oxygen fugacity during field-assisted sintering
T2 - TiO 2 as a test case
AU - Quach, Dat V.
AU - Levchenko, Andrey A.
AU - Navrotsky, Alexandra
AU - Groza, Joanna R.
PY - 2008/3
Y1 - 2008/3
N2 - Field-assisted sintering exposes samples in a graphite die to reducing conditions. Using TiO2 as a test case, this work shows that internal redox equlibria in the sample, rather than the graphite-CO-O2 equilibrium, appear to control the oxygen fugacity. Samples sintered at 1160°C for 20 min are homogeneous in oxygen content and have an average composition of TiO1.983±0.001. The oxygen fugacity during these sintering experiments is calculated to be about 10-16 atm, which is higher than the value obtained from thermodynamic equilibrium of graphite-CO-O2 at the given temperature. The oxygen fugacity is similar to that for the quasi-two-phase region, or hysteresis loop, representing the coexistence of reduced rutile with random crystallographic shear (CS) planes and the first ordered CS phase.
AB - Field-assisted sintering exposes samples in a graphite die to reducing conditions. Using TiO2 as a test case, this work shows that internal redox equlibria in the sample, rather than the graphite-CO-O2 equilibrium, appear to control the oxygen fugacity. Samples sintered at 1160°C for 20 min are homogeneous in oxygen content and have an average composition of TiO1.983±0.001. The oxygen fugacity during these sintering experiments is calculated to be about 10-16 atm, which is higher than the value obtained from thermodynamic equilibrium of graphite-CO-O2 at the given temperature. The oxygen fugacity is similar to that for the quasi-two-phase region, or hysteresis loop, representing the coexistence of reduced rutile with random crystallographic shear (CS) planes and the first ordered CS phase.
UR - http://www.scopus.com/inward/record.url?scp=40449138171&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=40449138171&partnerID=8YFLogxK
U2 - 10.1111/j.1551-2916.2007.02192.x
DO - 10.1111/j.1551-2916.2007.02192.x
M3 - Article
AN - SCOPUS:40449138171
SN - 0002-7820
VL - 91
SP - 970
EP - 974
JO - Journal of the American Ceramic Society
JF - Journal of the American Ceramic Society
IS - 3
ER -