Article

Dielectric and Electromechanical Properties of Rare Earth Calcium Oxyborate Piezoelectric Crystals at High Temperatures

State Key Lab. of Crystal Mater., Shandong Univ., Jinan, China
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control (Impact Factor: 1.5). 05/2011; 58(4):868 - 873. DOI: 10.1109/TUFFC.2011.1881
Source: IEEE Xplore

ABSTRACT The electrical resistivity, dielectric, and electromechanical properties of ReCa4O(BO3)3 (ReCOB; Re = Er, Y, Gd, Sm, Nd, Pr, and La) piezoelectric crystals were investigated as a function of temperature up to 1000°C. Of the studied crystals, ErCOB and YCOB were found to possess extremely high resistivity (p): p >; 3 × 107 ω.cm at 1000°C. The property variation in ReCOB crystals is discussed with respect to their disordered structure. The highest electromechanical coupling factor κ26 and piezoelectric coefficient d26 at 1000°C, were achieved in PrCOB crystals, with values being on the order of 24.7% and 13.1 pC/N, respectively. The high thermal stability of the electromechanical properties, with variation less than 25%, together with the low dielectric loss (<;46%) and high mechanical quality factor (>;1500) at elevated temperatures of 1000°C, make ErCOB, YCOB, and GdCOB crystals promising for ultrahigh temperature electromechanical applications.

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