The invention discloses a method for preparing a binary alternatively-doped BST membrane, belongs to the technical field of functional materials, and relates to a method for preparing a nanocrystalline BST membrane. The method adopts binary
doping of Mn and Y, namely, carries out Mn or Y
doping on an odd layer membrane and carries out Y or
Mn doping on an even layer membrane; and the method adds a pre-
crystallization processing step between cooling and
crystallization steps. The membrane prepared by the method is smooth and compact with no crack or shrinkage cavity, and can greatly enhance the comprehensive
dielectric tuning performance of the nanocrystalline BST membrane; and the obtained nanocrystalline BST membrane has a
dielectric tuning rate of over 30.0 percent, a
dielectric loss of less than 2.0 percent, a K factor of greater than 15.5, a high
dielectric strength and a stable
frequency characteristic and a temperature characteristic. The nanocrystalline BST membrane prepared by the method can be used for preparing a
microwave tuning device (such as a phase shifter) instead of a ferrite and a
semiconductor so as to remarkably reduce the manufacturing cost of the
microwave tuning device; and furthermore, the nanocrystalline BST membrane prepared by the method is applicable for magnetic recording, pyroelectric
focal plane arrays and the like.