High-temperature phosphor thermometry with YAG: Dy and LED excitation

We aim to extend the temperature range of phosphor thermometry as a diagnostic tool for the protective properties of thin flexible ceramic strips of Yttrium Stabilized Zirconia (YSZ) and its uses. Previous investigations demonstrated adequate optical transmission properties of Manganese doped Magnesium Flurogermanate and Lanthanum Oxysulphide thermometry between 90 C and 700 C using 405 nm diode laser excitation and several different phosphors. Also, in an earlier study, multiple layers of ceramic ribbons were tested in the temperature range reported. Here, YAG: Dy was selected for extending the range of applications to a higher temperature, nearing 1200 C. To accomplish this the thermographic phosphor was coated in a thin uniform layer of the YSZ ceramic ribbon. Using direct 365 nm UV LED excitation and monitoring from ⁴I_15/2 to ⁶H_15/2 transition at 456 nm. Temperature-dependent luminescence was observed from ambient to 1200 C. The decay characteristics did not show a strong temperature dependence up to ~900 C. However, with temperatures exceeding 900 C, the decay time decreased as a function of temperature. To the best of our knowledge, this is the first published use of LED excitation of a thermographic phosphor past 1000 C.