Strain relaxation in (Ba 0.60Sr 0.40)TiO 3 (BST) thin films on (110) orthorhombic NdGaO 3 substrates is investigated by x-ray diffractometry. Pole figure analysis indicates a  BST||[1̄10] NGO and  BST|| NGO in-plane and  BST|| NGO out-of-plane epitaxial relationship. The residual strains are relaxed at h ∼ 200 nm, and for h > 600 nm, films are essentially strain free. Two independent dislocations mechanisms operate to relieve the anisotropic misfit strains along the principal directions. The critical thickness for misfit dislocation formation along  and  are 11 and 15 nm, respectively. Stress analysis indicates deviation from linear elasticity for h < 200. The films with 10<h<25 nm are of monoclinic symmetry due to a finite principal shear stress along  of the initial orthorhombic cell.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy (miscellaneous)