Emission Spectroscopy of Eu-Doped CaF₂ under Static and Dynamic High Pressures

Abstract

The time-resolved emission spectra of the CaF2(Eu) crystal subjected to impact-induced shock compression in the inelastic region have been measured up to 31.6 GPa and the effect of shock and release waves on the Eu emission spectrum has been recorded. The Eu2+ spectrum centered at ∼425 nm shifts toward the longer wavelength with a shock pressure of up to ∼15 GPa, but no further shift has been observed at higher pressures. Emission spectra under static pressure have also been measured up to 10.2 GPa and compared with those under shock compression. A blue Eu2+ emission at ∼425 nm and a sharp orange Eu3+ emission at ∼590 nm are observed under static pressure. A large pressure shift of ∼2.2 nm/GPa is observed for the blue emission at pressures of up to ∼10 GPa, but the orange emission spectrum hardly moves against pressure. The Hugoniot determined for the CaF2(Eu) single crystal is Us=5.15+1.18Up.