リラクサ系圧電材料の開発とその医用超音波診断装置への応用  [in Japanese] Research and Development of Relaxor-Based Piezoelectric Materials and Their Application for Medical Echo Ultrasound  [in Japanese]

Echo ultrasound diagnostic equipment has been used for last 30 years. In this application, ultrasonic probes play an important role to realizing a good image on screen. In this article, the probe structure and materials used for the device are briefly introduced. In addition, many powders used for ultrasonic acoustic materials, such as lens, matching layer and backing are also introduced. High dielectric constant and high piezoelectric constant of lead-perovskite relaxor multicomponents system ceramics Pb(Sc1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-Pb(Ni1/3Nb2/3)O3-(Pb,SrBa)(Zr,Ti)O3 (PSN-PMN-PNN-PSZT) with high dielectric constant ε33T/ε0=5,000-7,200 and large planar mode electromechanical coupling factor (EMCF) kp > 69% near the morphotropic phase boundary are summarized. Some new materials, piezoelectric single crystals and low-attenuation acoustic lens material are also introduced.