  In this work, a new methodology for comparing high power performance of
different piezoelectric materials is presented. When comparing high power
performance of piezoelectric materials of varying compositions and vibration
modes, there exists an inherent problem in comparing the mechanical quality
factor directly. Typically the behavior of the mechanical quality factor is
reported as a function of tip vibration velocity of the sample. This paper
shows why this approach can be inherently problematic and proposes an energy
approach to characterize the mechanical quality factor as the solution. By
utilizing mechanical energy density ($u_{e}$), the mass density of the material
system ($\rho$), and the vibration mode shape (e.g. $k_{31}$ and $k_{p}$) of
the sample are accounted for. Therefore, a better method to compare high power
performance of varying piezoelectric compositions is introduced. Furthermore,
the new method is applied to various compositions by using data available in
the literature. As a result, the high power behavior of the materials appear to
be significantly different when the new "energy density approach" is used to
compare the mechanical quality factor rather than vibration velocity. Also, the
technique's ability to be utilized to consolidate data from different
resonators to determine anisotropic loss factors is demonstrated on hard and
soft PZT samples of $k_{31}$ and $k_{p}$ geometries.
