Effects of Ta5+ substitution on mechanical and microwave dielectric properties of R(Nb1-xTax)2O6 ceramics

Microwave dielectric ceramics (MWDCs) are prone to mechanical failure, and improving the mechanical properties of MWDCs is of significance for their application under extreme conditions. Novel high-entropy R(Nb1-xTax)2O6 (R = Mg0.2Mn0.2Co0.2Ni0.2Zn0.2) ceramics were prepared by the solid-phase reaction method. The single-phase and composite solid solutions of the R(Nb1-xTax)2O6 series were successfully prepared, as evidenced by XRD, Raman spectra, and combined with EDS energy spectrum analysis. The average grain size was found to increase with the Ta5+ content, while the grain dispersion exhibited a trend of increasing and then decreasing, resulting in a trend of increasing and then decreasing Q×f. The replacement of Nb5+ by Ta5+ has been demonstrated to improve τf and enhance the mechanical properties. An increase in Ta5+ content from 0.5 to 0.75 results in a significant enhancement in εr and mechanical properties, which is primarily attributed to the generation of the RTa2O6 phase. When x = 1, the R(Nb1-xTax)2O6 ceramics exhibit excellent microwave dielectric properties (εr = 31.28, Q×f = 20,722, τf = 48.36) and the most favorable mechanical properties (Hv = 7.99 GPa, σ = 882 MPa, TRS = 237.7 MPa). This study provides a new idea to improve the mechanical properties of MWDCs. •Five ions co-occupy the R-site to form a high-entropy ceramic.•High entropy design improves mechanical properties of R(Nb1-xTax)2O6 ceramics.•Ta5+ substitution improves the mechanical properties of R(Nb1-xTax)2O6 ceramics.