A Calculation of Physical Constants of Ceramic Barium Titanate

The dielectric, piezoelectric and elastic constants of polycrystalline ceramics at room temperature are calculated by averaging those values of single crystals on the assumption that the ceramic is composed of spherical crystallites. The calculated values are in good agreement with observed ones, showing that the piezoelectric effects in each single crystal (especially d 15 at room temp.) play a great part in determining the properties of the ceramic. Also the method is shown for calculating elastic constants of polycrystals which consist of spherical crystallites in all directions, with the calculated values of metals (Au, Ag, Cu, Fe etc.) in the cubic system. The “ destressing factor ”, which gives the relations between the internal stress of the sphere and the stress in the surrounding medium, is defined and calculated.