Ba_3La_3Ti_4Nb0_(18): a new microwave dielectric of A_6B_5O_(18)-type cation-deficient perovskites

摘要

A new A_6B_5O_(18)-type cation-deficient perovskite Ba3La3Ti4NbOig was prepared by the conventional solid-state reaction route. The phase and structure of the ceramics were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM). The compound crystallizes in the trigonal system with unit cell parameter a=5.6198(1) A, c=41.6402(4) A, F=1138.90(l) A~3, and Z=3. The microwave dielectric properties of the ceramic were studied using a network analyzer, and it shows a high dielectric constant of 47.44, a high-quality factors with QXf of 17,729 GHz, and a positive tf of+35.2 ppm deg C~1.