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 synchrotron radiation on the identical SrTiO3 crystal used in neutron and x-ray-scattering experiments before, unambiguously show that the bulk critical scattering above T-c = 99.5 K does not exhibit a sharp component, which had been found in recent x-ray-diffraction experiments. The observed temperature dependence of the inverse correlation length is in excellent agreement with the neutron data. However, scattering on two length scales was observed in a near-surface volume element of the same crystal.