A low-cost (Mg 1- x Ca x ) 3 B 2 O 6 (0 ≤ x ≤ 1.0 mol.%) ceramic with enhanced microwave dielectric properties

A low-cost (Mg 1- x Ca x ) 3 B 2 O 6 (0 ≤ x ≤ 1.0 mol.%) (MC x B) microwave dielectric ceramic was prepared by solid-state method. X-ray diffraction, scanning electron microscope, and vector network analyzer were adopted to characterize the phase composition, microstructure, and microwave dielectric properties of the as-fabricated MC x B ceramics. All the MC x B ( x = 0–1.0 mol.%) ceramic samples exhibit the singe orthorhombic structure corresponding to Mg 3 B 2 O 6 (JCPDS 75–1807). Excellent microwave dielectric properties ( ε r = 6.8, Q × f = 103,556 GHz, τ f = − 34.5 ppm/°C at 12.6 GHz) were obtained in the MC 0.002 B ( x = 0.2 mol.%) ceramic sintered at 1250 °C for 3 h, making it a prospective candidate for the practical application in portable terminal and wireless communications.