Piezoelectric hysteresis analysis and loss separation

Losses in piezoelectrics are approached by considering a description of dir ect stress-charge displacement hysteresis. Shortcomings of the usual loss m odels (viscous and Rayleigh, taken separately) are briefly demonstrated. Th en, a mixed model for piezoelectric losses superimposing viscous and Raylei gh types of descriptions is proposed and validated for a modified lead tita nate and lead zirconate titanate (PZT). It is shown for PZT that viscous an d Rayleigh-like loss contributions can be effectively separated by fitting the piezoelectric hysteresis loop with an expression combining the two loss y responses. The possibility to obtain all the necessary parameters that de scribe piezoelectric stress nonlinearity from one single piezoelectric loop is also demonstrated in the case of PZT. The origins of the mixed loss beh avior are interpreted as arising from domain wall motion in terms of intern al friction mechanisms and of pinning energy ranges. (C) 2001 American Inst itute of Physics.