A novel Na _{1− x} K _x TaO ₃ perovskite microwave dielectric ceramic with high permittivity and high positive temperature coefficient

Abstract

A novel Na 1−x K x TaO 3 (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 NaTaO 3 structure of space group Pmcn, and larger grain and lower porosity were observed after adding an appropriate amount of K + ions. The Q × f value is majored by the packing fraction and grain size, while the value of τ f is influenced by Ta-O bond valence. The Na 0.95 K 0.05 TaO 3 ceramic possesses excellent dielectric properties of ε r = 164.29, Q × f = 9091 GHz (f = 3.15 GHz), tanδ = 3.46×10 -4 , τ f = +809.52 ppm/℃, sintered at 1550 ℃. Compared with NaTaO 3 ceramics, the Na 1−x K x TaO 3 ceramics prepared in this study demonstrate higher dielectric constants and higher positive temperature coefficients, which are promising for device miniaturization and τ f compensators.