Microwave dielectric properties of temperature stable MO-ZrO2-Ta2O5 ceramics

Temperature stable MO-ZrO 2 -Ta 2 O 5 ceramics (M = Co, Ni) were prepared by solid state route. Crystal structure was determined by X-ray diffraction and Raman spectrum. Single-phase MZrTa 2 O 8 was formed through the reaction between intermediate MTa 2 O 6 and residual ZrO 2 . Quantitative phase analysis verified that changing temperature considerably adjusted the chemical compositions of ceramics. In the case of CoZrTa 2 O 8 , the optimum dielectric properties were ε r ∼24.3, Q  ×  f∼ 95,300 GHz ( Q ∼11,305 at 8.43 GHz), and τ f   ∼  -30.50 ppm/°C. The NiZrTa 2 O 8 ceramic had ε r  = 23.5, Q  ×  f  = 86,404 GHz ( Q ∼10,774 at 8.02 GHz), and τ f  = −20.20 ppm/°C. Their large τ f values were compensated since MZrTa 2 O 8 and MTa 2 O 6 had opposite τ f . Particularly, near zero τ f of −2.67 and 0.22 ppm/°C were obtained for M = Co, Ni at 1150 and 1175 °C, respectively.