The majority of commonly used electrostrictive ceramics are based on lead manganese niobate. These ceramics display large electrostriction strain coefficients ≈ 10^-16 m²/V² at frequencies up to a few kHz. However, they suffer from major drawbacks: they require high driving currents (dielectric constant >10000), contain toxic elements, and are incompatible with thin film Si-microfabrication techniques.

We have recently reported that ceria ceramics doped with aliovalent cations having crystal radii smaller than that of cerium, display increased high frequency (f >100Hz) longitudinal electrostriction strain coefficients |M|. For instance, with 10 mol% Lu³⁺ or Yb³⁺ lanthanide dopants, |M| ~ 10^-17 m²/V² is observed for f >100Hz . Despite Y_ceria ~200GPa and e_ceria ~ , these electrostriction strain coefficients are 100-fold larger than estimated on the basis of Newnham’s scaling law for “classical” electrostrictors. Such “non-classical” behavior has been attributed to the formation of highly polarizable, elastic dipoles reorienting under external electric field.

Surprisingly, doping with small isovalent dopants, such as Zr and Hf , produces an increase in |M| to , independent of frequency up to several kHz, as determined by converse electrostriction measurements. The introduction of Zr raises the dielectric constant more than predicted by the Clausius-Mossotti relation. This suggests that the presence of a small dopant creates a highly polarizable unit which may be responsible for the large electrostriction strain coefficient. Our results demonstrate that, by systematically adjusting the composition of ceria-based solid solutions, the possibility exists for development of technologically useful electrostrictive materials which are, at the same time, ecologically sound and fully compatible with Si-microfabrication.