Plasticity and an Inverse Brittle-to-Ductile Transition in Strontium Titanate

The use of ceramic materials is often restricted by a transition from ductile behavior to brittle fracture with decreasing temperature. For example, strontium titanate (SrTiO3 ) is known to be extremely fragile and brittle below 1300 K. It is therefore surprising to find that SrTiO3 single crystals can be deformed in compression below 1050 K again. Extensive plastic deformation up to 7% strain at low yield stresses of the order of only 120 MPa is possible at room temperature. Low temperature plasticity is carried by the same <110>{1bar 1 0} dislocations as the high temperature deformation along the <001> axis. From this we conclude that these dislocations must exist in two different core configurations