On the real structure of profiled anion-deficient corundum

Profiled Al₂O₃ single crystals grown by Stepanov's method to obtain anion-deficient composition were characterized by neutron diffraction at T =300 K for the first time. Whereas the main structure motif of investigated crystals is checked to be of corundum-type, the scattering pictures of as-grown crystal demonstrate pronounced anomalies being probably indications on substructure forming. However, neutron scanning of synthesised crystal taken after annealing under restoring conditions reveals additional effects associated with displacement type superstructure. (paper)