Lead-free(Ba,Sr)TiO_(3)-based ceramics with superior tunable properties by the semi-solution method

High-performance dielectric tunable materials with both high dielectric tunability and low dielectric loss are urgently needed for new-generation electronic tunable devices.In the present study,a new system,(Ba_(0.675)Sr_(0.325))_(1−x)La_(x)Ti_(1−x)MnxO_(3)(x=0.25%,0.5%,0.75%,and 1.0%),was designed.The acceptor dopant Mn was added to lower dielectric loss,while the donor dopant La was introduced to enhance dielectric tunability.The samples were prepared using the conventional solid-state(CS)reaction method and the semi-solution(SS)method.The experimental results showed that the morphology of the ceramics was optimized by further improving the processing procedure.Dense microstructures,homogeneous grains,and uniform dopant distributions could be achieved successfully by the semi-solution method.Moreover,a significant enhancement in the tunable properties was realized owing to the improved microstructure mentioned above.The optimum tunable properties occurred in the samples prepared by the semi-solution method at x=0.75%,with a high dielectric tunability of 85.0%,a low dielectric loss of 0.0011,and an excellent figure of merit(FOM)of 773.The tunable properties of(Ba,Sr)TiO_(3)(BST)ceramics were even superior to those of lead-based materials,with an FOM of approximately 700.All the results suggested that the semi-solution method rendered BST ceramics more promising for applications in tunable devices.