evelopment of new optically active materials as pressure and temperature sensors

For the study of Biological systems in the sublevels of the crust, the temperature and pressure domains (-20 to 200ºC and 0.1 to 2 GPa) can be easily reproduced with low pressure devices. Difficulties come when trying to choose a calibrant (fluorescent dyes or proteins) that may give fast and accurate measurements of the pressure and temperature conditions in the hydrostatic chamber. On the other hand, for Earth studies in the limit of the inner and outer mantle, the pressure and temperature domains are larger (0 to 1100 K, 0.1 to 30 GPa) and conventional high pressure DAC can be used. Whereas the pressure determination with ruby is widely used, the measurement of the exact temperature in some experiments is still a challenge.

Diamonds and other gemstones used as typical anvils (moissanite, sapphire, etc) are transparent to visible light. Therefore, the easiest method of measuring the pressure in the hydrostatic chamber is using the fluorescence properties of optically active species (rare earth ions, transition metal ions, dye molecules or fluorescent proteins). Less standardized is the method used to measure the sample temperature in the hydrostatic chamber. For temperatures up to 1000 K fluorescent materials can still be used: the ruby up to 700 K, in strictly hydrostatic conditions, Sm2+:SrB4O7 or Sm:YAG. Above this temperature, external systems have to be used; spectroscopic pyrometry and thermocouples, although uncertainties in the determination of the temperature are usually large. As follows from the above examples, the high pressure research still needs more sensitive pressure and/or temperature sensors. In this project we propose the detailed spectroscopic study and characterization of three potential calibrants and the development of low-cost prototypes:
     • Low pressure calibrant
     • Spatially resolved pressure sensors
     • Temperature and high pressure calibrant