Effect of Mn2+ substitution on the dielectric properties of NaMg(PO3)3 ceramics at microwave and terahertz frequencies

In this study, NaMg 1- x Mn x (PO 3 ) 3 (0.00 ≤  x  ≤ 0.0625) ceramics with low dielectric constant were prepared via the solid-state reaction method. The effects of Mn 2+ substitution on the microstructure and dielectric properties (at microwave and terahertz frequencies) of the NaMg(PO 3 ) 3 ceramics were studied by means of the Rietveld refinement, morphology, and ionic polarizability analysis. It is obtained that the NaMg 0.0975 Mn 0.025 (PO 3 ) 3 ceramic sintered at 880 °C for 4 h exhibited optimal dielectric properties at microwave frequencies, where ε r  = 4.585, Q  ×  f  = 48,313 GHz (@17.228 GHz), and τ f  = −40.83 ppm/°C. The Q  ×  f and τ f values were changed by 74.2 % and 27.8 %, as compared to the values of 27,728 GHz and −56.52 ppm/°C for the pure NaMg(PO 3 ) 3 ceramic, respectively. For terahertz frequencies (0.2–1.0 THz), the ε r values were decreased to 3.79–3.98, and the tan δ values were between 0.0203 and 0.1152. All the experimental results indicate that this system exhibits great potentials both at microwave and terahertz frequencies.