Microstructures and dielectric tunable properties of Ba sub(0.5)Sr sub(0.5)TiO sub(3)-MgO-Mg sub(2)TiO sub(4) composite ceramics

• Published in: Journal of materials science. Materials in electronics Vol. 24; no. 7; pp. 2372 - 2378
• Main Authors: He, Yanyan, Zhao, Jingyuan, Xu, Yebin, Li, Changnian, Zhu, Yao
• Format: Journal Article
• Language: English
• Published: 01.07.2013
• Subjects: Ceramics; Curie temperature; Dielectric constant; Dielectric properties; Electronics; Ferroelectric materials; Magnesium oxide; Microwaves
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-013-1104-7

Ba sub(0.5)Sr sub(0.5)TiO sub( 3)-MgO-Mg sub(2)TiO sub(4) composite ceramics were prepared by a solid-state reaction method, and the dielectric tunable properties were investigated. It is observed that the addition of MgO-Mg sub(2)TiO sub(4) into the Ba sub(0.5)Sr sub(0.5)TiO sub(3) forms ferroelectric (Ba sub(0.5)Sr sub(0.5)TiO sub(3))-dielectric (Mg sub(2)TiO sub(4)-MgO) composites. Increasing Mg sub(2)TiO sub(4) content causes an increase of Curie temperature T sub(c) towards room temperature and a decrease of dielectric constant peak epsilon sub(max). The dielectric constant and loss tangent of Ba sub(0.5)Sr sub(0.5)TiO sub(3)-MgO-Mg sub(2)TiO sub(4) composites have been reduced and the overall tunability is maintained at a sufficiently high level. With the increase of Mg sub(2)TiO sub(4) content and the decrease of MgO content, the dielectric constant and tunability of Ba sub(0.5)Sr sub(0.5)TiO sub(3)-MgO-Mg sub(2)TiO sub(4) composite ceramics increase and the Q f values decrease. Ba sub(0.5)Sr sub(0.5)TiO sub(3)-Mg sub(2)TiO sub(4)-MgO composites have dielectric constant of 123.0-156.5 and tunability of 14.4-28.5 % at 10 kHz under 3.9 kV/mm, indicating that they are promising candidate materials for tunable microwave applications requiring a low dielectric constant.