Extraction of Pt/Rh/ZrO2 high temperature elastic constants

A recently developed thin Pt/Rh/ZrO₂ film has been successfully used as electrode material for high temperature acoustic wave device applications up to 1000°C. In order to accurately model and design high temperature acoustic wave devices, the elastic properties of the Pt/Rh/ZrO₂ film are required. In this work, a surface acoustic wave (SAW) method is developed to extract the elastic constants of a co-deposited Pt/Rh/ZrO₂ thin film both before and after annealing at 850°C. SAW delay lines are fabricated on multiple langasite (LGS) orientations with Pt/Rh/ZrO₂ metalized delay paths. The group velocity of each delay line is measured and input into the matrix method for SAWs in order to extract the independent elastic constants c₁₁ and c₄₄ of the thin film. Preliminary values of the Pt/Rh/ZrO₂ elastic constants before and after annealing are reported here for the first time. Elastic constants for the unannealed film vary from the platinum constants by 48% in c₄₄ and 12% in c₁₁. These results reveal the importance of characterizing this new film in order to apply it in the design of high temperature acoustic wave devices.