Structure, bond characteristics and microwave dielectric properties of new A0.75Ti0.75Ta1.5O6 (A=Ni, Co, Zn and Mg) ceramics based on complex chemical bond theory

Tri-rutile structured A(0.75)Ti(0.75)Ta(1.5)O(6) (A=Ni, Co, Mg, Zn) ceramics were synthesized using traditional solid reaction method. The crystal structures were studied by X-ray diffraction in conjunction with Rietveld refinement analysis. Based on the complex chemical bond theory and crystallographic data, some principle chemical bond characteristics such as bond ionicity, lattice energy, bond energy and coefficient of thermal expansion of complex A(0.75)Ti(0.75)Ta(1.5)O(6) ceramics were obtained through quantitative calculation. The calculated results provided useful information to clarify the correlations between chemical bond characteristics and microwave dielectric properties of A(0.75)Ti(0.75)Ta(1.5)O(6) ceramics. The dielectric constant was closely associated with the ionicity of Ta-O bond, and the Q x f values were correlated with the lattice energy of Ta-O bond. The tau(f) values were affected by the bond energy of Ta-O bond and the coefficient of thermal expansion of A-O bond.