Ba8ZnTa6O24: A New High Q Dielectric Perovskite

The hexagonal perovskite, Ba8ZnTa6O24, was prepared in single-phase form and was found to be a stable secondary phase, formed as a result of the loss of ZnO from Ba(Zn1/3Ta2/3)O3 microwave dielectrics. The experimental and calculated X-ray patterns of Ba8ZnTa6O24 indicate it is isostructural with Ba8Ta6NiO24 with an 8H (cchc)2 close-packed BaO3 stacking sequence and the lattice parameters, a=10.0825(14), c=19.0587 (38)Å . High-density ceramics of Ba8ZnTa6O24 could be prepared at temperatures considerably lower (1400oC) than those used to sinter pure Ba(Zn1/3Ta2/3)O3, and exhibit very good microwave dielectric properties with ε=30.5, Qf=62300, and τf=+36 ppm/oC at 8.9 GHz. Comments Copyright The American Ceramic Society. Reprinted from Journal of the American Ceramic Society, Volume 88, Article Number 8, August 2005, pages 2126-2128. This journal article is available at ScholarlyCommons: http://repository.upenn.edu/mse_papers/78 Ba8ZnTa6O24: A New High Q Dielectric Perovskite M. Thirumal and P. K. Davies* Department of Materials Science & Engineering, University of Pennsylvania, Philadelphia, Pennsylvania, 19104-6272 The hexagonal perovskite, Ba8ZnTa6O24, was prepared in single-phase form and was found to be a stable secondary phase, formed as a result of the loss of ZnO from Ba(Zn1/3Ta2/3)O3 microwave Q2 dielectrics. The experimental and calculated X-ray patterns of Ba8ZnTa6O24 indicate it is isostructural with Ba8Ta6NiO24 with an 8H (cchc)2 close-packed BaO3 stacking sequence and the lattice parameters, a5 10.0825(14), c5 19.0587 (38)Å. High-density ceramics of Ba8ZnTa6O24 could be prepared at temperatures considerably lower (14001C) than those used to sinter pure Ba(Zn1/3Ta2/3)O3, and exhibit very good microwave dielectric properties with e5 30.5, Qf5 62 300, and sf5136 ppm/1C at 8.9 GHz.