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

High unloaded quality factor (Q(u)), zero temperature coefficient of resona nt frequency (tau (f)) and high relative permittivity (epsilon (r)) microwa ve dielectric ceramics have been fabricated based on BaZn1/3Nb2/3O3. Proper ties 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)=3 5, and tau (f)=0. The new compounds are disordered according to x-ray diffr action (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 inten sity, 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 Americ an Institute of Physics.