Effect of Reoxidation on the Grain‐Boundary Acceptor‐State Density of Reduced BaTiO 3 Ceramics

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