Effect of La 2O 3 doping on the tunable and dielectric properties of BST/MgO composite for microwave tunable application

Abstract

Undoped and La 2O 3doped (0.5, 1.0, 2.0, 3.0 wt.%) Ba 0.55Sr 0.45TiO 3/MgO composites were prepared by traditional ceramic processing and their structural, surface morphological, tunable properties and their dielectric properties at low frequency and microwave frequency were systemically examined. The result shows that La 2O 3 dopant has a strong effect on the average grain size. The La 2O 3 doped samples have lower temperature coefficient of capacitance than the undoped. The 0.5 wt.% La 2O 3 doped sample has a little higher tunability than the undoped and the tunability of other doping concentration samples is lower as compared to the undoped. The addition of La 2O 3 decreases the dielectric constant and increases quality factor ( Q × f) at microwave frequency. The 0.5 wt.% La 2O 3 doped samples have the best properties among these samples and have a higher tunability, lower dielectric constant and lower dielectric loss tangent at microwave frequency and these properties are very beneficial to the development of the tunable devices application.