Effect of Ni substituted MgZrTa${}_2$O${}_8$ ceramics on sintering characteristics and microwave dielectric properties

Herein, Mg${}_{1-x}$Ni${}_x$ZrTa${}_2$O${}_8$ (x = 0, 0.1, 0.3, 0.5, 0.8, 1) ceramics are synthesized using a solid-phase reaction method. Ni${}^{2+}$ replacing Mg${}^{2+}$ improves the drawback of high sintering temperature and poor temperature stability. The samples have a relative density above 95% at the optimal sintering temperature. The sintering temperature of Mg${}_{1-x}$Ni${}_x$ZrTa${}_2$O${}_8$ reduces from 1475 to 1400 °C. And single-phase Mg${}_{1-x}$Ni${}_x$ZrTa${}_2$O${}_8$ ceramics with monoclinic wolframite structures are analyzed. According to the Rietveld refinement results, with the doping of Ni${}^{2+}$, the transformation of unit cell volume leads to the shift of the main peak in the X-Ray diffraction pattern to a higher angle in 0 ≤ x ≤ 0.3 and a lower angle in 0.5 ≤ x ≤ 1. The ε${}_r$ of Mg${}_{1-x}$Ni${}_x$ZrTa${}_2$O${}_8$ is comparable to MgZrTa${}_2$O${}_8$. At 1400 °C, the Q × f is increased from 10 598 GHz in the undoped sample to 43 041 GHz in Mg${}_{0.9}$Ni${}_{0.1}$ZrTa${}_2$O${}_8$ ceramic. The absolute values of τ${}_f$ of ceramic samples decrease with the excessive Ni${}^{2+}$. The desirable dielectric properties (ε${}_r$ = 20.79, Q × f = 43 041 GHz, τ${}_f$ = -33.04 ppm °C${}^{-1}$) are obtained at 1400 °C. Ni substitution is effective for MgZrTa${}_2$O${}_8$ ceramic to optimize densification temperature and retain the high Q × f value. (© 2024 Wiley‐VCH GmbH)