ORIGIN OF THE CRITICAL SCATTERING ON 2 LENGTH SCALES IN SRTIO3 - A HIGH-ENERGY SYNCHROTRON-RADIATION DIFFRACTION STUDY

High-q-resolution diffraction experiments performed with 100 keV synch rotron radiation on the identical SrTiO3 crystal used in neutron and x -ray-scattering experiments before, unambiguously show that the bulk c ritical scattering above T-c = 99.5 K does not exhibit a sharp compone nt, which had been found in recent x-ray-diffraction experiments. The observed temperature dependence of the inverse correlation length is i n excellent agreement with the neutron data. However, scattering on tw o length scales was observed in a near-surface volume element of the s ame crystal.