3-DIMENSIONAL DIELECTRIC-DISPERSION EQUATION FOR ZN-TA-TA SYSTEM IN BA(ZN1 3TA2/3)O3 CRYSTAL/

This paper describes the procedure for deriving a three-dimensional di electric dispersion equation. As a crystal model, the Ba(Zn, Ta)O3 com plex perovskite structure is chosen and three ions, one zinc and two t antalum, are used in the derivation of the dispersion equation. The dy namical matrix for the system Zn-Ta-Ta is derived first. From the eige nvalues and the eigenvectors of this matrix, the resonant frequencies and the forms of the normal modes for this system are determined. With use of the eigenvectors for infrared-active modes, the equation of mo tion under an applied field is derived for each ion. The dielectric di spersion equation is given from the equation of motion for each infrar ed-active mode.