Thermoelectric Properties of Zn\u3csub\u3ex\u3c/sub\u3eIn\u3csub\u3ey\u3c/sub\u3eO\u3csub\u3ex\u3c/sub\u3e+\u3csub\u3e1.5y\u3c/sub\u3e Films

Ceramic thin film thermocouples are being developed to replace noble metal thermocouples operating within the harsh environments of advanced turbine engines used for power generation and propulsion. Seebeck coefficients as large as 158 V/°C were determined for indium oxide (In2O3) at 950°C and 256 V/°C for zinc oxide ZnO at 1250°C relative to platinum reference electrodes. Because these Seebeck coefficients are appreciably larger than those for metallic thermocouples, alloys in the system indium zinc oxide ZnxInyOx+1.5y were investigated by cosputtering from high purity ZnO and In2O3 targets. Thermocouple libraries were patterned with platinum reference electrodes and rapidly screened using combinatorial chemistry techniques. Thermoelectric response, power, and resistivity were determined for each thermocouple in the library. Thermocouples with the optimum compositions were prepared and the resulting power factor of the biceramic junctions was determined from 75 to 650°C