Compressive creep of dense BaTiO_3 having linear-intercept grain sizes of 19.3--52.4 mu m was investigated at l200-1300 deg C by varying the oxygen partial pressure from l02 to 10~5 Pa in both constant-stress and constant-crosshead-velocity modes. Microstructures of the deformed materials were examined by scanning and transmission electron microscopy. The stress exponent was ≈ l, the grain-size dependence was rs 1/d~2, and the activation energy was ≈ 720 kJ/mole. These parameters, combined with the microstructural observations (particularly grain displacement and absence of deformation-induced dislocations), indicated that the dominant deformation mechanism was grain-boundary sliding accommodated by lattice cation diffusion. Because of the absence of an oxygen partial pressure dependence, diffusion was probably controlled extrinsically.
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