Giant electrostriction in bulk RE (III) substituted CeO2: effect of RE 3+ and its concentration

Recent discovery of giant electrostriction in rare earth (RE (III)) substituted ceria (CeO2) thin films driven by electroactive defect complexes and their coordinated elastic response, expands the material spectrum for electrostrain applications beyond the conventional piezoelectric materials. Especially Gd substituted CeO2, with Gd concentration >10% seems to be an ideal material to obtain such large electrostrain response. However, there are not many experimental studies that systematically investigate the effect of RE (III) ion-defect interaction and RE concentration on electrostriction. Here we perform structure-property correlation studies in bulk ceramics of RE3+ substituted ceria doped with RE=Y, La and Gd at various concentrations upto a maximum of 20%, to understand the features responsible for giant electrostriction. Our results show that Y substituted ceria, with atleast 20% Y substitution, is clearly both a giant M and a Q electrostrictor at low frequencies (<20 Hz), and this correlates with the unique attractive defect-dopant interaction of Y with oxygen vacancies. La has a repulsive interaction with oxygen vacancies, and La doped ceria at all the studied compositions (upto 20%) does not show giant electrostiction. Gd has a neutral interaction, and only 20% Gd doped ceria at best falls at the border of classification between giant and non-giant electrostrictors at frequencies <0.05 Hz. Our work takes a step back from thin-films and assesses the fundamental defect features required in the design of giant electrostrictors.