Low-temperature plasticity and flow-stress behaviour of strontium titanate single crystals

The plasticity of single-crystalline strontium titanate below ambient temperature was studied by means of compression tests using samples with compression axis parallel to 〈0 0 1〉. Deformability was observed down to 43 K. The critical resolved shear stress (CRSS) derived from the stress–strain curves increases in a non-monotonic manner with decreasing temperature. This increase is characterized by three regimes with different temperature dependences of the CRSS and shows a remarkable step at about 210 K. Polarized light microscopy applied to transparent specimens revealed that 〈1 1 0〉 {1 1 0} slip systems are dominant throughout the whole temperature regime. The regime behaviour is studied using stress relaxation experiments which provide promising evidence for a straightforward interpretation of the phenomena on the basis that different dislocation cores and dislocation motion modes may be responsible for the three-regime behaviour.