THERMODYNAMIC CONSIDERATIONS OF THE GRAIN-SIZE DEPENDENCY OF MATERIAL PROPERTIES - A NEW APPROACH TO EXPLAIN THE VARIATION OF THE DIELECTRIC PERMITTIVITY OF BATIO3 WITH GRAIN-SIZE

Phase transitions which depend on grain size induce very interesting properties in materials such as zirconia or barium titanate. A new and rigorous thermodynamic treatment of this type of phase transition is proposed with consideration of the surface phenomena. An interpretation is given of the observed differences when the material - particularly BaTiO3 - under consideration is a fine grain powder or is a fine grain ceramic.