Structure and Mechanism Studies of High Conductivity Solid Ionic Conductors.

摘要

The structures and mechanisms of ion transport have been studied for key representatives of the class of superionic conductors (i.e.,substances exhibiting ionic conductivity orders of magnitude larger than those of the classical defect ionic conductors). The structural and crystal chemical factors which control ionic conductivity in Type III or liquid like conductors have been determined by means of a neutron diffraction study of single crystals of beta-alumina and beta-alumina. The mechanism of ion migration in beta-alumina,and its dependence on additives of foreign ions,were investigated also by wide band nuclear magnetic resonance. Additional information was obtained by means of conductivity measurements at microwave frequency,and by experiments at very high pressure. The research effort has included a detailed investigation into the structure and conductivity of Ag2HgI4as a prime example of the other kind of superionic conductor. Using single crystals a tetragonal structure was established whose conductivity is appreciably electronic. The details of the alpha-beta transformations at 50C were ascertained and a complete structure determination of the alpha-form was made. (Modified author abstract)