Characterization of crystal structure and microwave dielectric properties of AZrNb2O8 (A=Zn, Co, Mg, Mn) ceramics based on complex bond theory

Single phase AZrNb2O8 (A=Zn,Co,Mg,Mn) ceramics with monoclinic wolframite structure were prepared and characterized by crystalline structure refinement for the investigation on the correlations between crystal structure and microwave dielectric properties. A semiempirical method based on the complex bond theory was used to calculate the bond ionicity, lattice energy, and coefficient of thermal expansion of AZrNb2O8 ceramics. The crystal structure changed with the variation of A site ions and affected the Nb-O octahedral correspondingly. Due to the variation of crystal structure, the observed bond ionicity was helpful to understand the electric polarization. The variation of the Q·ƒ and τƒ values could be attributed to the lattice energy and coefficient of thermal expansion respectively. The microwave properties of AZrNb2O8 ceramics were strongly dependent on the chemical bond ionicity, lattice energy and coefficient of thermal expansion.