Structure of BaTiO3

The theoretical model for the ferroelectric effect in barium titanate (Mason and Matthias, 1948) assumes a displacement of the titanium from the center of the unit cell in the z direction, probably due to the formation of a covalent bond with the c-centered oxygen. This displacement had been observed earlier by Dr. Danielson (Danielson, Matthias, and Richardson, 1948) and given as about 0.16A, at 20°C. This value, based on the relatively high intensity of x-ray scattering from the 0-0-11 plane, as shown by a Weissenberg pattern using molybdenum radiation was later brought into question by work at the Institute for Atomic Research (Danielson and Rundle, 1949), using silver radiation