High temperature thermo-mechanical properties of praseodymium doped ceria thin films measured two ways

Abstract

The temperature dependence of a mixed ionic electronic conducting (MIEC) material's thermo-chemical expansion coefficient, biaxial modulus, and/or Young's modulus are crucial in determining the internal stress, strain, and/or mechanical stability of the various electrochemical devices (batteries, fuel cells, gas sensors, etc.) utilizing them. This work compares the temperature-dependent thermo-chemical expansion coefficient, biaxial modulus, and Young's modulus of Pr_0.1Ce_0.9O_1.95−δ (10PCO) MIEC thin films obtained using two different techniques: (1) a “dual substrate” technique where in-plane stress measurements were collected on “identical” 10PCO thin films atop two different substrate compositions, and (2) a “dual characterization” technique were out-of-plane strain measurements and in-plane stress measurements were performed on a single sample. Both techniques indicated that from 500 to 700 °C (1) the average 10PCO thermo-chemical expansion coefficient in the (100) plane increased from ∼12.5 to ∼17.5 ppm, (2) the 10PCO biaxial modulus in the (100) plane was roughly constant at ∼300 GPa, and (3) the average 10PCO Young's modulus in the (100) plane was roughly constant at ∼175 GPa.