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Published in:
31-05-2016
Tuning the temperature coefficient of resonant frequency for 8-layer twinned hexagonal perovskite Ba8ZnTa6O24 ceramics
Published in: Journal of Materials Science: Materials in Electronics | Issue 10/2016
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Abstract
High-Q dielectric materials ilmenite MgTiO3, columbite MgNb2O6 and cubic perovskite Ba3NiTa2O9 with negative temperature coefficient of resonant frequency (τ
f
) were selected as candidates for compensating the τ
f
of hexagonal perovskite Ba8ZnTa6O24. X-ray diffraction data shows that Ba8ZnTa6O24 coexists with Ba3NiTa2O9 but is not compatible with MgTiO3 and MgNb2O6 at high temperature. The τ
f
for the mixed hexagonal/cubic perovskite Ba8ZnTa6O24–Ba3NiTa2O9 system is tunable via the temperature compensation effect and its quality factor may be improved via annealing the ceramics at high temperature to enhance the cation ordering in the cubic component. Permittivity ε
r
~ 22–25, Q×f > 30,000 GHz and tunable τ
f
within ±10 ppm/°C were achieved in the range of about 50–80 wt% Ba3NiTa2O9 for the hexagonal/cubic perovskite composite Ba8ZnTa6O24–Ba3NiTa2O9 ceramics, which is suitable for the application as dielectric resonators and filters.