Mechanical, thermal, and electrochemical properties of Pr doped ceria from wafer curvature measurements

This work demonstrates, for the first time, that a variety of disparate and technologically-relevent thermal, mechanical, and electrochemical oxygen-exchange material properties can all be obtained from in situ, current-collector-free wafer curvature measurements. Specifically, temperature or oxygen partial pressure induced changes in the curvature of 230 nm thick (100)-oriented Pr0.1Ce0.9O1.95−x (10PCO) films atop 200 μm thick single crystal yttria stabilized zirconia or magnesium oxide substrates were used to measure the biaxial modulus, Young's modulus, thermal expansion coefficient, thermo-chemical expansion coefficient, oxygen nonstoichiometry, chemical oxygen surface exchange coefficient, oxygen surface exchange resistance, thermal stress, chemical stress, thermal strain, and chemical strain of the model mixed ionic electronic conducting material 10PCO. The (100)-oriented thin film 10PCO thermal expansion coefficient, thermo-chemical expansion coefficient, oxygen nonstoichiometry, and Young's modulus (which is essentially constant, at ∼200 MPa, over the entire 280–700 °C temperature range in air) measured here were similar to those from other bulk and thin film 10PCO studies. In addition, the measured PCO10 oxygen surface coefficients were in agreement with those reported by other in situ, current-collector-free techniques. Taken together, this work highlights the advantages of using a sample's mechanical response, instead of the more traditional electrical response, to probe the electrochemical properties of the ion-exchange materials used in solid oxide fuel cell, solid oxide electrolysis cell, gas-sensing, battery, emission control, water splitting, water purification, and other electrochemically-active devices.