Ba 0.5Sr 0.5TiO 3-Bi 1.5Zn 1.0Nb 1.5O 7 composite thin films with promising microwave dielectric properties for microwave device applications

Abstract

Crack-free, dense, and uniform Ba 0.5Sr 0.5TiO 3(BST)-Bi 1.5Zn 1.0,Nb 1.5,O 7(BZN) composite thin films were deposited on (100) LaAlO 3, (100) SrTiO 3, and (100) MgO substrates via a pulsed laser deposition, using a combined target of BST and BZN ceramics. Phase composition and microstructure of the BST-BZN thin films were characterized by x-ray diffraction and scanning electron microscopy. The films, on LAO, STO, and MgO substrates, showed zero-field microwave (∼7.7 GHz) dielectric constants of 471, 435, and 401, dielectric loss tangents of 0.0048, 0.0043, and 0.0037, and dielectric tunabilities of 6.2%, 6.0%, and 5.7% at ∼8.1 kV/cm, respectively. The good physical and electrical properties of the BST-BZN composite thin films make them promising candidates for microwave device applications. © 2004 American Institute of Physics.