Analysis on the anisotropic electromechanical properties of lead magnoniobate titanate single crystal for ring type ultrasonic motors

This work discussed the optimized cut of single crystal lead magnoniobate titanate (PMNT) for use of ring type travelling wave ultrasonic motors (USMs), according to anisotropic analysis on electromechanical properties. The selection criterion of crystal orientation relies on the circular uniformity of the induced travelling wave amplitude on the stator surface. By calculating the equivalent elastic coefficient c₁₁ and lateral piezoelectric constant d₃₁, the optimal crystal orientations were proposed for PMNT single crystals poled along different directions. For single crystal poled along <001>_c directions, the optimal orientation lies along [001]_c with d₃₁=-1335pC/N and k₃₁=0.87. The crystallographic orientation [025]_c is the optimized orientation for single crystals poled along <011>c direction with d₃₁=199pC/N and k₃₁=0.55. The optimal orientation of 1R configuration is [332]c with a large enhancement of d₃₁ = 1201 and k₃₁=0.92.