Niobate-based microwave dielectrics suitable for third generation mobile phone base stations

Abstract

High unloaded quality factor (Qu), zero temperature coefficient of resonant frequency (τf) and high relative permittivity (εr) microwave dielectric ceramics have been fabricated based on BaZn1/3Nb2/3O3. Properties have been optimized for the composition, 0.9Ba([Zn0.60Co0.40]1/3Nb2/3)O3–0.1Ba(Ga0.5Ta0.5)O3 for which Qu=32 000 @ 3.05 GHz, εr=35, and τf=0. The new compounds are disordered according to x-ray diffraction (XRD) and may be indexed using a simple perovskite unit cell, a=4.09 Å. Small peaks (e.g., d≈3.01 Å, relative intensity, 4.5) attributed to a barium niobate second phase are also present in XRD patterns. These ceramics are suitable in terms of cost and performance for base stations supporting third generation architecture.