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

Abstract

Crack-free, dense, and uniform Ba0.5Sr0.5TiO3(BST)–Bi1.5Zn1.0Nb1.5O7(BZN) composite thin films were deposited on (100)LaAlO3, (100)SrTiO3, 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 (∼7.7GHz) 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 ∼8.1kV∕cm, respectively. The good physical and electrical properties of the BST–BZN composite thin films make them promising candidates for microwave device applications.