Pressure effect on phosphor thermometry using Mg4FGeO6:Mn

This study examined the effect of ambient pressure on the luminescent lifetime of Mg4FGeO6:Mn phosphors in different morphologies. To evaluate the pressure sensitivity of phosphor in the form of particle, agglomerated particle and chemically bonded coating, samples including phosphor powder, a pressed phosphor disc, and chemically bonded phosphor coating were fabricated and calibrated using a PMT-based measurement system for a pressure range of 20–200 kPa and a temperature range of 298–873 K. The results showed no obvious pressure effect on the lifetime of the chemically bonded Mg4FGeO6:Mn coating. However, the lifetime of the phosphor powder and pressed phosphor disc decreased as the pressure increased. This pressure effect was most obvious for the pressed phosphor disc, which was further aggravated at higher temperatures. The atomic distance between the manganese ion and other atomics reduced as the pressure increased, which induced the movement of an excited state in the configuration coordinate. Considering this dependency of pressure sensitivity on phosphor morphology, it is important to adopt the same fabrication procedure for calibration and temperature measurement using Mg4FGeO6:Mn. In addition, for in-flow measurement using Mg4FGeO6:Mn tracer particles, the influence of environmental pressure must be considered.