Electrical conductivity-defect structure correlation of variable-valence and fixed-valence acceptor-doped BaTiO(3) in quenched state.
Insulation resistance degradation of dielectric BaTiO(3) is expected to be closely correlated to its defect structure frozen in from elevated processing temperatures. For BaTiO(3), respectively doped with variable-valence (Mn(Ti)) and fixed-valence acceptors (Al(Ti)), their defect structures were frozen in by quenching at different equilibrium oxygen activities in the range of -18 < log a(O(2))< or = 0 at 1000 and 900 degrees C, respectively, and their electrical conductivities were measured against temperature in the range of 200 < or =T/K < or = 494 by impedance spectroscopy. Frozen-in defect structures were calculated and compared with the conductivity as measured in the quenched state. A close correlation has been confirmed between the bulk conductivity as measured in the quenched state and the frozen-in defect structure as calculated. The effects of variable- and fixed-valence acceptor impurities on the defect structure and electrical conductivity in the quenched state are highlighted in the light of hole trapping, and the charge transport behavior in the quenched state is discussed.
Yoo
Han-Ill
HI
Department of Materials Science and Engineering, Seoul National University, Seoul, 151-744, Korea. hiyoo@snu.ac.kr
Oh
Tae-Sik
TS
Kwon
Hyung-Soon
HS
Shin
Dong-Kyu
DK
Lee
Jong-Sook
JS