Microwave dielectric properties of BaTi4O9-BaSm2Ti4O12 composite ceramics

BaTi4O9 and BaSm2Ti4O12 possess large dielectric performances and low dielectric loss, but their temperature-dependent properties could not meet with the practical use. In this paper, a composite ceramic system BaTi4O9/BaSm2Ti4O12 (BaTi4O9 + xSm(2)O(3), x = 20, 40, 60, 80 mol%) was prepared and their dielectric properties was presented. The composite ceramic precursor were modeled by a cool iso-static press (CIP) and calcined at 1300 degrees C for 6 h. The measured densities of ceramic samples increased, but the relative densities decreased with the increase of x. XRD patterns showed there existed two phases of BaTi4O9 and BaSm2Ti4O12 in the composite. The dielectric constants increased from 39.7 to 60.0, while the quality factors decreased from 8300 to 1500. At x = 40%, a near-zero temperature coefficient of + 2.2ppm/degrees C was achieved. The presence of pores, Ti3+ and Ti2+ was proposed to be the cause of the deviation from calculated dielectric properties. (C) 2013 The Ceramic Society of Japan. All rights reserved.