Enhanced dielectric properties of (Ba,Sr)TiO₃//Ba(Zr,Ti)O ₃ heterostructures with optimized structure design

Environment-friendly ferroelectric Mn:BST//Mn:BZT heterostructures were epitaxially deposited on (001) MgO substrates by pulsed laser deposition with different combination ratios of Mn:BST over Mn:BZT, 2.5:7.5; 1:1; and 7.5:2.5. The microstructural studies indicate that the in-plane interface relationships between the heterostructures and the substrate are determined to be (001) _Mn:BST//(001)_Mn:BZT//(001)_MgO and [100] _Mn:BST//[100]_Mn:BZT//[100]_MgO. The K _u band microwave (15.5-18 GHz) dielectric property characterizations show that the dielectric constant, dielectric loss, and tunabilities of the heterostructures are highly dependent upon the sequences of Mn:BST to Mn:BZT. The optimized dielectric tunability with a low loss tangent was found to be 58.1%-74.4% under the combination ratio of 1:1 for Mn:BST to Mn:BZT, which suggests that the as-grown ferroelectric heterostructures can be developed for room temperature tunable microwave elements and related device applications.