Zero temperature coefficient of frequency crystal cuts in monoclinic NdCa4O(BO3)3 piezoelectric crystals
The temperature coefficient of frequency (TCF) was investigated in monoclinic NdCa4O(BO3)3 (NdCOB) piezoelectric crystals over the temperature range of -140 °C to 200 °C. A zero TCF characteristic was achieved for the (ZXw) 15° crystal cut, with turnover point at 20 °C. The electromechanical coupling k26 and piezoelectric coefficient d26, in shear vibration mode, were determined to be 25% and 13.5 pC/N, respectively. The zero TCF crystal cut, large coupling factor and high piezoelectric coefficient, together with a high mechanical quality factor (Q > 10,000), demonstrate NdCOB crystals promising candidates for bulk acoustic wave resonators over a wide temperature range. 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.