Ultralow dielectric loss of Y and Mn alternately doped nonstoichiometric BST films

摘要

A 1% Y and 1% Mn alternately doped nonstoichiometric (Ba0.6Sr0.4)(0.8)TiO3 (Y/Mn-BST) film was attempted to design and prepare by an improved sol-gel method on Pt/Ti/SiO2/Si substrates, and its ultralow dielectric loss with other dielectric properties was studied in this paper. Undoped, Y doped and Mn doped BST films were also compared. All films grow along (110) orientation and show polycrystalline cubic ABO(3) perovskite structures. Pure film shows the weakest crystallization, while Y/Mn-BST film exhibits the strongest crystallization. Superfluous Ti acted as Ti doping makes B sites so saturated that superfluous Ti4+ ions have to enter A sites and first replace Sr2+ ions and then replace Ba2+ ions to show donor doping, thus result in the smallest lattice parameter and decreased Ba/Sr ratio. Doped Y3+ or Mn2+ ions only enter A sites and replace Ti4+ ions to reveal acceptor doping, and thuscause lattice parameters and Ba/Sr ratio a little larger than the undoped BST film. The Y/Mn-BST film shows the largest lattice parameter and increased Ba/Sr ratio with acceptor doping. Each nonstoichiometric BST film show smaller capacitance, tunability and dielectric loss than normal BST film, but the Y/Mn-BST film reveals better combination of dielectric properties in particular much smaller dielectric losses of 0.0051 approximate to 0.0067, thus show more obvious practicability and reliability in tunable microwave applications.