EFFECT OF REOXIDATION ON THE GRAIN-BOUNDARY ACCEPTOR-STATE DENSITY OF REDUCED BATIO3 CERAMICS

To investigate the effect of reoxidation on the grain-boundary acceptor-state density of reduced barium titanate, n-doped BaTiO3 ceramics are sintered in a reducing atmosphere (2% H-2 + 98% N2) and then annealed in oxygen. After annealing at 1150-degrees-C for different times, the experimental results show a relationship between temperature-averaged acceptor-state density and annealing time as N(s) = N(SO)Bt1/n with n between 2 and 3. An inherent acceptor-state density N(SO) = 4.25 x 10(12) cm-2 is obtained with an increase rate B = 4.8 x 10(12) cm-2.min-1/3, when n reaches 3. The inherent grain-boundary acceptor states in the reduced n-doped BaTiO3 ceramics are believed not due to adsorbed oxygen ions.