Patent attributes
A piezoelectric buzzer includes a vibrating layer capable of withstanding temperatures in excess of 260° C. for at least five minutes while still maintaining its ability to vibrate and produce a buzzing sound at a level of at least 80 dB, and a high temperature piezoelectric material having a Curie temperature in excess of 260° C. and one or more of the following properties: a planar coupling coefficient (kp) of at least about 0.5; a longitudinal coupling coefficient (k33) of at least about 1500; and a mechanical quality factor (Qm) of at least about 2000. The piezo material may have a combination of these properties such that the product (kp2)(k33)(Qm) is at least about 1.5×106. The piezoelectric material may have a base formula of PbxSr(1-x)(Mn1/3Sb2/3)(1-y)(ZrzTi1-z)yO3 with x ranging from 0.95 to 0.99, y ranging from 0.92 to 0.97, and z ranging from 0.45 to 0.55, and may further include dopants in the amounts of about 0.4% CeO2, about 1% CuO, and about 4% Nb2O5.
