The correlations among bond ionicity, lattice energy and microwave dielectric properties of (Nd1-xLax)NbO4 ceramics

摘要

(Nd1-xLax)NbO4 ceramics were prepared via a conventional solid-state reaction route and the correlations among bond ionicity, lattice energy, phase stability and microwave dielectric properties were investigated. The diffraction patterns showed that the (Nd1-xLax)NbO4 ceramics possessed a monoclinic fergusonite structure. The chemical bond ionicity, bond covalency and lattice energy were calculated using the empirical method. The phase structure stability varied with the lattice energy which resulted due to the substitution content of La3+ ions. With the increase of La3+ ion contents, the decrease of Nd/La-O bond ionicity was observed, which could be attributed to the electric polarization. epsilon(r) has a close relationship with the Nd/La-O bond covalency. The increase of the Q x f values and tau(f) values could be attributed to the change in the lattice energy. The microwave dielectric properties of (Nd1-xLax)NbO4 ceramics with a monoclinic fergusonite structure were strongly dependent on the chemical bond ionicity, bond covalency and lattice energy.