摘要
The BiAlO_(3)(BA)and(Bi_(0.5)Na_(0.5))ZrO_(3)(BNZ)are selected to form a solid solution with(K_(0.48)Na_(0.52))NbO_(3) via traditional solid state technique to optimize the electrical performance and temperature stability of KNNbased lead-free ceramics,simultaneously.Here we show that doped BA has a great influence on phase structure,morphologies,and electrical properties.The XRD patterns and dielectric constant versus temperature curves reveal that an increase in the BA content results in a transform of phase structures from a coexistence state of rhombohedral,orthorhombic and tetragonal phases to pseudocubic phase.Owing to the construction of R-O-T phase boundary,optimized performances(T_(C)~336℃,d_(33)~306 pC/N,kp=0.48)are obtained in 0.962(K_(0.48)Na_(0.52))NbO_(3)-0.003BiAlO_(3)-0.035(Bi_(0.5)Na_(0.5))ZrO_(3)(KNN-3)ceramics.Based on the sintered KNN-3 ceramic samples,high-frequency ultrasound imaging transducers are designed and fabricated,which exhibits a high center frequency of 24.5 MHz,a broad -6 dB bandwidth of 97% and a high-sensitivity.Finally,the imaging characteristic of the lead-free transducers is demonstrated via ex vivo imaging of biological tissue structure.As environment friendly materials,the excellent electrical and acoustic performance of developed KNN-based ceramics has great potential for practical applications.
基金
supported by the Supported by Sichuan Science and Technology Program(No.2019YJ0096)
the National Natural Science Foundation of China(51932010,51332003)
the Fundamental Research Funds for the Central Universities of China
supported by the China Scholarship Council(File no.:201706240056).
