Sintering behaviour, lattice energy and microwave dielectric properties of melilite-type BaCo2Si2O7 ceramics

A novel melilite-type compound BaCo2Si2O7 with monoclinic structure (C2/c) was prepared via solid-state reaction method. The correlations amongst microstructure, crystal structure, bond ionicity, lattice energy and microwave dielectric properties were systematically analyzed. The microwave dielectric properties of BaCo2Si2O7 ceramics were determined by extrinsic (pores) and intrinsic (lattice energy) factors. The dielectric constant (e(r)), quality factor (Q x f) and temperature coefficient of resonant frequency (tau(f)) were dominated by the relative density and the lattice energies of Si-O and Ba-O bonds. Optimum microwave dielectric properties for BaCo2Si2O7 ceramics were obtained when sintered at 1060 degrees C for 3 h: e(r) = 9.26, Q x f = 31 135 GHz and tau(f) = -92.05 ppm C-1.