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

High unloaded quality factor (Q(u)), zero temperature coefficient of resonant frequency (tau (f)) and high relative permittivity (epsilon (r)) microwave dielectric ceramics have been fabricated based on BaZn1/3Nb2/3O3. Properties have been optimized for the composition, 0.9Ba([Zn0.60Co0.40](1/3)Nb-2/3)O-3-0.1Ba(Ga0.5Ta0.5)O-3 for which Q(u)=32 000 @ 3.05 GHz, epsilon (r)=35, and tau (f)=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 Angstrom. Small peaks (e.g., d approximate to3.01 Angstrom, 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. (C) 2001 American Institute of Physics.