H. X. Liu

Characterization and dielectric properties of Ba5NdZnM9O30 (M=Nb, Ta) ceramics

Ba5NdZnM9O30 (M=Nb, Ta) ceramics were prepared by the conventional high temperature solid state reaction route. The sintered samples were characterized by X-ray diffraction and scanning electron microscopy methods. They belong to paraelectric phases of filled tetragonal tungsten bronze structure at room temperature and have high dielectric constants of 282 and 85, combined with low dielectric losses of 0.0048 and 0.0081 at 1 MHz for Nb- and Ta-based ceramics, respectively.

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 (Qu×f >18 700 at 5.4422 GHz), and a small temperature coefficient of resonant frequency (τf)+12 ppm °C−1 at room temperature; Ba3Nd2Ti2Nb2O15 has a higher dielectric constant of 46.83 with high-quality factors Qu×f >19 500 at 5.0980 GHz, and τf+28 ppm °C−1.