A novel Na_1-xK_xTaO₃ perovskite microwave dielectric ceramic with high permittivity and high positive temperature coefficient

A novel Na1-xKxTaO3 (x = 0, 0.025, 0.05, 0.075, 0.1, and 0.15) ceramic with high permittivity and high positive temperature coefficient was synthesized via the conventional solid-state method. All samples were determined to be pure phase orthorhombic NaTaO3 structure of space group Pmcn, and larger grain and lower porosity were observed after adding an appropriate amount of K+ ions. The Q x f value is majored by the packing fraction and grain size, while the value of tf is influenced by Ta-O bond valence. The Na0.95K0.05TaO3 ceramic possesses excellent dielectric properties of epsilon(r) = 164.29, Q x f = 9091 GHz (f = 3.15 GHz), tan delta = 3.46x10(-4), tau(f) = +809.52 ppm/degrees C, sintered at 1550 degrees C. Compared with NaTaO3 ceramics, the Na1-xKxTaO3 ceramics prepared in this study demonstrate higher dielectric constants and higher positive temperature coefficients, which are promising for device miniaturization and tau(f) compensators.