| Abstract Scope |
Rare earth orthophosphate ceramics are being investigated for a range of turbine applications because of their ability to withstand extreme environments, while in the geosciences, the persistence of these same materials allows them to record geologic events. This class of materials exhibits pressure-induced phase transformations that are generally characterized using synchrotron x-ray diffraction and Raman spectroscopy in diamond anvil cells. This talk explores in situ photoluminescence spectroscopy for monitoring phase evolution under pressure. Photoluminescence spectroscopy is uniquely sensitive to the local bonding environment, is widely available, and produces data with high signal-to-noise ratio. We find that direct excitation photoluminescence spectroscopy detects the xenotime-monazite phase transition onset and end pressure in TbPO4 consistent with synchrotron x-ray diffraction results. Even though the phase transition reverts upon release of pressure, characteristic optical signatures at ambient pressure are identified that encode prior stress history, both below and above the phase transition onset pressure. |