High-temperature deformation behavior in SrTiO3 ceramics

The high-temperature deformation behavior of a polycrystalline strontium titanate (SrTiO3) ceramic (6 μm grain size) was investigated at temperatures of 1200–1345 °C in an argon atmosphere. Compressive deformation tests were conducted at strain rates ranging from 5 × 10−6 to 5 × 10−5 s−1. Steady-state flow stresses were 0.05–30 MPa and increased with increasing strain rates. Stress exponents of ≈1, at temperatures >1200 °C, indicated a viscous diffusion-controlled deformation with an activation energy of ≈628 ± 24 kJ/mol. Comparison of activation energy with literature data suggests diffusion of cations as the rate-controlling mechanism. Absence of cavitation and grain-shape changes were consistent with grain-boundary sliding as the principal deformation mechanism. The electron back-scattered diffraction (EBSD) technique was used to determine the grain orientation as a function of applied strain. The results indicate that some of the grains rotate with cumulative rotation as large as 7° at a strain of 4%.