Significant reduction of dielectric loss of Ba0.51Sr0.34TiO3 film modified by Y/Mn alternate doping and preheating

Abstract

To achieve significant reduction of dielectric loss and enhancement of dielectric tunability for actual applications, a Ba0.51Sr0.34TiO3 film modified by Y/Mn alternate doping (Y/Mn-BST0.85) is prepared by an improved sol-gel method, where the film is composed of 12 layers, and odd number layers are preheated. For comparison, BST0.85, Y-BST0.85 and Mn-BST0.85 films are also prepared. XRD shows four films are ABO3 cubic perovskite structures. The BST0.85 film shows the smallest lattice parameter and donor doping because rich Ti4+ ions enter into A sites to replace some Sr2+ and Ba2+ ions. Besides the donor doping, three doped BST0.85 films exhibit slightly larger lattice parameters and acceptor doping because Y3+ or Mn2+ ions replace some Ti4+ ions at A sites. The Y/Mn-BST0.85 film shows the largest lattice parameter and the strongest crystallinity because Y-BST0.85 layer and Mn-BST0.85 layer match well in lattice structure. Compared to stoichiometric films, four nonstoichiometric films show markedly decreased dielectric losses. The Y/Mn-BST0.85 film exhibits the lowest dielectric loss with 0.45 ~ 0.54% under the conditions of − 40 to 40V and 100 kHz, and 0.43 ~ 2.29% under the conditions of 10 Hz ~ 1 GHz and 0 V, thus can satisfy actual applications including tunable microwave application at high frequencies. The related mechanisms are studied by measuring leakage current density, observing AFM and analyzing XPS besides analyzing the XRD patterns.