Electromechanical properties of electrostrictive CeO2:Gd membranes: Effects of frequency and temperature

Abstract

Doped ceria is known for decades as an excellent ionic conductor used ubiquitously in fuel cells and other devices. Recent discovery of a giant electrostriction effect has brought world-wide interest to this class of materials for actuation applications in micromechanical systems. From this aspect, the electromechanical response has to be studied as a function of external parameters, such as frequency, temperature, and electrode material. In this work, we fabricated circular membranes based on Gd-doped ceria (CGO) with Ti electrodes and studied their electromechanical response using a sensitive interferometric technique. The self-supported membranes are flat at room temperature and reversibly buckle upon heating, indicating that the membranes are under in-plane tensile strain. We have found that the electromechanical response is strongly frequency dependent. Significant hysteresis is observed in the displacement-vs.-voltage curves, which is deleterious for micromechanical applications but can be eliminated by tuning the phase of the excitation voltage. The electromechanical response of the system increases with temperature. Finite Element Modeling is applied to evaluate the electrostriction coefficient of the CGO material. At low frequencies, the M12 electrostriction coefficient is about 5 × 10−18 m2/V2, which is in line with the previous reports.

Thermal excitation contribution into the electromechanical performance of self-supported Gd-doped ceria membranes

“…We have demonstrated that the electrode material [10] becomes even more important in the high operating frequency range (100 Hz-10 kHz). The principally different behavior of the membranes with Al and Ti electrodes at low frequencies is attributed to the formation of Schottky-barriers at the Al electrode/material interface, while at frequency about few MHz both membranes become thermally excited.…”

Effect of oxygen defects blocking barriers on gadolinium doped ceria (GDC) electro-chemo-mechanical properties

“…Despite intriguing, some questions about the role of oxygen vacancies and microstructure on electrostriction still remains unexplored [12]. Besides, Lubomirsky and coworkers suggested a power law dependence of I-V relationship in grain boundary blocking behavior based on space charge mechanisms [18] [19] and demonstrated that an increase of grain boundary resistance leads to a decrease in the portion of applied voltage drop in the bulk, decreasing electromechanical properties [20].…”

Electro‐chemomechanical Contribution to Mechanical Actuation in Gd‐Doped Ceria Membranes

“…Previously, we have demonstrated the feasibility of mechanical actuation with CGO‐based devices and have shown that the choice of contact metal is critical for functionality . Of the electrodes tested, titanium contacts were found to display the lowest resistance . However, the electromechanical response of micro‐electromechanical systems (MEMS) based on CGO films was found to be complex .…”