Abstract Because no real material is a perfect insulator, but has some small electrical conductivity, under static circumstances the piezoelectric equations are not applicable to any real material and, hence, have no physical significance. On account of the existence of real current, when the time-dependence is sufficiently slow, the zero charge equation of electrostatics does not apply and must be replaced by the equation of the continuity of electric charge.
1998 IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 45:1-3
© 1998, by The Institute of Electrical and Electronics Engineers, Inc. All rights reserved.