Extrinsic effects on microwave dielectric properties of high-Q MgZrTa₂O₈ ceramics

MgZrTa₂O₈ ceramics with excellent microwave dielectric properties had been prepared through conventional mixed oxide route. All the sintered samples exhibited a single phase with wolframite structure type belonged to P2/c (C _2h ⁴ ) space group. The Raman spectrum revealed a similar lattice vibration in all samples with different sintering temperature. Emphatically, the extrinsic effects on microwave dielectric properties had also been investigated. The microwave dielectric properties of MgZrTa₂O₈ ceramics presented a significant dependence on the sintering condition. The porosity-corrected permittivity (ε-pc) was calculated to investigate the influence of the porosity to the dielectric constant (ε_r). For the high-dense MgZrTa₂O₈ ceramics, the main factors which had influences on quality factors (Q × f) were the grain size and grain-size distribution. The temperature coefficient of resonant frequency (τ _f ) was depended on the dielectric constant and pores. The typical microwave dielectric properties of MgZrTa₂O₈ ceramics were ε_r = 22.76, Q × f = 131,500 GHz, τ _f  = −33.81 ppm/°C, sintered at 1475 °C.