Residual Stress in Damaged SrTiO3Single Crystals

The residual stress introduced in SrTiO 3 crystals by lapping, grinding and cutting is examined using a polarizing microscope. The parallelepiped specimens with {100} faces or {100} and {110} faces are damaged on one {100} or {110} face. The extinction directions in the damaged face and in faces normal to its face coincide with the directions along the edges of the specimen. This indicates that the resultant residual stress has its normal components only and no shear components with respect to the faces of the specimen. The analysis leads to the conclusion that lapping induces a weak tensile stress along the damaged face and a strong compressive stress normal to its face, while grinding or cutting work induces only a strong tensile stress along its face and normal to its face. The observed residual stress is of the order of 10 7 to 10 8 dyn/cm 2 in magnitude at a depth of 100 µm from the damaged surface.