Dielectric, elastic and piezoelectric properties of RCa4O(BO3)3 (R = rare-earth elements) crystals with monoclinic structure of point group m

• Published in: Journal of crystal growth 2009-01, Vol.311 (3), p.916-920
• Main Authors: SHIMIZU, Hiroyuki, NISHIDA, Takashi, TAKEDA, Hiroaki, SHIOSAKI, Tadashi
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Dielectric, piezoelectric, ferroelectric and antiferroelectric materials; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Elasticity, elastic constants; Exact sciences and technology; Growth from melts; zone melting and refining; Materials science; Mechanical and acoustical properties of condensed matter; Mechanical properties of solids; Methods of crystal growth; physics of crystal growth; Physics; Structure of solids and liquids; crystallography; Structure of specific crystalline solids
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2008.09.144

Rare-earth calcium oxoborate RCa4O(BO3)3 (R=La, Gd, Y) piezoelectric single crystals were successfully grown by a conventional RF-heating Czochralski (Cz) technique. They belong to the monoclinic system with point group m, and have 27 independent material constants. We developed the determination scheme (cuts and vibration modes) of the material constants in point group m. Their material constants were evaluated on the basis of the determination scheme and systematically compared. Also, the Rayleigh surface acoustic wave (RSAW) velocities v and coupling factors K2 for the fundamental X-, Y- and Z-cuts were theoretically simulated in their crystals by Campbell and Jones's method, which showed a good agreement with the measured values. Moreover, from the calculated result in their all propagation direction, it was confirmed that (180 deg, 120 deg, 167 deg )-cut of the RCa4O(BO3)3 (R=Y) and (180 deg, 146 deg, 167 deg )-cut of the RCa4O(BO3)3 (R=La), indicated excellent RSAW propagation properties when compared with existing piezoelectric crystals.