E0020

Phase Equilibria and Crystallography of Electronic Ceramics. W. Wong-Ng, R.S. Roth, T.A. Vanderah, H.F. McMurdie, L.P. Cook, B. Toby and Q. Huang, Materials Science and Engineering Laboratory, National Institute of standards and Technology, Gaithersburg, MD 20899.

The disciplines of phase equilibria and crystallography are strongly correlated. Both phase equilibrium and crystallographic research in the electronic materials area in the Ceramics Division of NIST have been important programs since the 1930’s. To produce new products and to improve present methods of production of ceramic materials, it is important to know the equilibrium relations and melting relations of the compounds and the polymorphic forms of the phases involved. This information is shown in phase diagrams produced by experimental work. Development of new technologies in electronic ceramics has continued to require new materials. Crystal structural investigation is important for understanding the physical properties and crystal chemistry of new materials. Throughout these years of phase equilibrium research, NIST has collaborated with various ceramic industries, and the systems investigated reflected the changing emphasis of material systems. As a result of the phase equilibriium work, a large number of new phases have been discovered and characterized at NIST using single crystal/powder diffraction methods. These materials include dielectrics, ferroelectrics, ionic conductors, superconductors, microwave materials, and magnetic materials.

In addition, a continuing relation between NBS/NIST and the American Ceramic Society since 1933 has resulted in the publication of twelve annual volumes of compilations and several volumes of diagrams in special areas.

In this talk, an overview of the phase equilibria and crystallographic research at NIST will be given.