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

High unloaded quality factor ${\mathrm{(Q}}_u\mathrm{),}$ zero temperature coefficient of resonant frequency ${\mathrm{(\tau }}_f)$ and high relative permittivity ${\mathrm{(\epsilon }}_r)$ microwave dielectric ceramics have been fabricated based on ${\mathrm{BaZn}}_{\mathrm{1/3}}{\mathrm{Nb}}_{\mathrm{2/3}}{\mathrm{O}}_3.$ Properties have been optimized for the composition, $\text{0.9}{\mathrm{Ba([Zn}}_{\mathrm{0.60}}{\mathrm{Co}}_{\mathrm{0.40}}{\mathrm{]}}_{\mathrm{1/3}}{\mathrm{Nb}}_{\mathrm{2/3}}{\mathrm{)O}}_{\mathrm{3}}{\mathrm{–0.1Ba(Ga}}_{\mathrm{0.5}}{\mathrm{Ta}}_{\mathrm{0.5}}{\mathrm{)O}}_3$ for which $Q_u\text{=32\hspace{0.05em}000}$ @ 3.05 GHz, ${\epsilon }_r\text{=35,}$ and ${\tau }_f\text{=0.}$ The new compounds are disordered according to x-ray diffraction (XRD) and may be indexed using a simple perovskite unit cell, $\text{a=4.09}$ Å. Small peaks (e.g., $\text{d≈3.01}$ 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.