Dielectric, Elastic and Piezoelectric Constants of Lanthanum Calcium Oxoborate Single Crystals with Monoclinic Structure of Point Group m

In this study, we propose using the d33 mode of a d33/d31 meter, new cuts and vibration modes to evaluate electroacoustical constants (dielectric, elastic and piezoelectric constants) of a piezoelectric crystal belonging to point group m. All material constants at room temperature of lanthanum calcium oxoborate LaCa4O(BO3)3 single crystals were thereby determined. The piezoelectric constants d 11 and d 33 measured by the d33 meter were 2.1 and 1.5 pC/N, respectively. The others were determined by the resonance-antiresonance method using various cuts in which the length-extensional mode and/or face-shear mode can be generated. The elastic compliances s 44 E , s 55 E and s 66 E were 35×10-12, 18×10-12 and 18×10-12 m2/N, respectively. Moreover, in order to investigate the dependence of the Rayleigh surface acoustic wave (RSAW) velocity and coupling coefficient k 2 on propagation direction, theoretical analysis by computer simulations was carried out for the Z-cut using the elastic compliances obtained in this study. The dependence of RSAW velocity on propagation direction calculated using the elastic compliances obtained did not agree with measurement results, but the calculated results were significantly improved and closer to measurement results.