Impact of high-energy milling synthesis on the electrostriction performance of Ce0.9Zr0.1O2

Abstract

Electrostrictors have the capacity to unidirectionally convert electrical energy into a mechanical response. The best electrostrictors known so far have a high content of toxic lead (Pb) in their composition. To solve this environmental issue, research efforts shifted to lead-free electrostrictor compositions, such as the ceria-based compounds. Ceria-based materials present “giant” electrostriction, and amongst them, Ce0.9Zr0.1O2 can be a suitable lead-free substitute. To advance in the implementation of green chemistry principles for electromechanically active materials and to determine the ramifications of its employment on functional properties of fluorite-based CeO2 - ZrO2 mixed oxides, we successfully synthesized a Ce0.9Zr0.1O2 solid solution using a high-energy milling-assisted method. Nanometric milled powders exhibit the fluorite structure and a homogeneous dispersion of Zr in the ceria matrix that is preserved after sintering dense pellets. Soft X-ray absorption measurements reveal the predominance of Ce4+ species and the limited presence of oxygen vacancies in Ce0.9Zr0.1O2. Impedance spectroscopy measurements reveal highly resistive behavior, characterized by a strong overlap of grain and grain boundary contributions. The Ce0.9Zr0.1O2 dielectric constant measured at room temperature is twice that of undoped ceria, εr ≈ 66, which is related to improved electromechanical response. Longitudinal electrostriction measurements support this assessment, reaching values of up to 1.7⋅10−17 m2 V−2 near the kHz frequency.