Preparation and characterization of two new dielectric ceramics Ba4NdTiNb3O15 and Ba3Nd2Ti2Nb2O15

Two new cation-deficient hexagonal perovskites Ba4NdTiNb3O15 and Ba3Nd2Ti2Nb2O15 were prepared in the BaO-Nd2O3-TiO2-Nb2O5 system by high temperature solid-state reaction route. The phase and structure of the ceramics were characterized by X-ray diffraction and scanning electron microscope (SEM). The microwave dielectric properties of the ceramics were studied using a network analyzer. Ba4NdTiNb3O15 has a dielectric constant of 38.15, a high-quality factors (Q(u) x f > 18700 at 5.4422 GHz), and a small temperature coefficient of resonant frequency (tau(f)) + 12 ppm degreesC(-1) at room temperature; Ba3Nd2Ti2Nb2O15 has a higher dielectric constant of 46.83 with high-quality factors Q(u) x f > 19 500 at 5.0980 GHz, and tau(f)+ 28 ppm degreesC(-1). (C) 2004 Kluwer Academic Publishers.