Scaling effects of ferroelectric nanoparticles studied by synchrotron radiation X-ray diffraction

High-resolution synchrotron X-ray powder diffraction measurement with multiple-detector system has been performed to investigate the scaling effect in ferroelectric PbxSr1−xTiO3 nanoparticles at ambient temperature with various sizes ranging from 10 to 200 nm and various compositions. The peak profiles of the 200 reflections show a large broadening and asymmetry for all particle sizes with decreasing particle size, implying the formation of gradational lattice structure induced by inhomogeneous strain. On the other hand, asymmetric and wide peak profiles of the 200 reflections become a wide symmetry with decreasing x. The crystal structure of PST at ambient temperature were indexed in a tetragonal system for x > 0.4 and in a cubic one for x ≤0.4. This result indicates that a tetragonal-cubic phase boundary exists around x~ 0.4.