Compositional variation within the Pb(Mg1/3Nb2/3) O3–PbTiO3–(Ba, Sr)TiO3(hereafter PMN–PT–BT,ST) ternary (6.4% PT% 14.1%, 1.25% BT,ST% 2.5%) results in major changes in induced strain and hysteresis. For the 1.25% BT family, the increase in strain correlates with an increase inTmax, while the dielectric loss is uncorrelated with hysteresis and strain. In addition, weak field aging (which is not reset by application of field) shows little effect on strain and hysteresis for drive fields of>0.2 MV/m. The vary narrow polarization‐fields loops (virgin curvesnearly indistinguishable from subsequent cycles) show that weak‐field permittivity is a good approximation to the high‐field permittivity. is a good approximation to the high‐field Permittivity. Although these data clarify the frequency (Tmaxis linearly dependent on the logarithm of the frequency) effect on weak‐field dielectric behavior, they do not directly address the question of meaningful extrapolation of high‐field strain with frequency. In particular, the question remains as to whether the high‐field permittivity and strain are frequency dependent. In future papers we will address this question by a combination of measurement techniques as f