Photoluminescence and Raman study of the high-pressure behavior of monoclinic (Eu1-Yb )2O3 solid solution

The high-pressure behavior of (Eu1-xYbx)2O3 solid solution with Yb3+ content (x) between 0 and 0.2 and monoclinic (B-type) crystalline structure has been studied by means of Raman and photoluminescence spectroscopies up to 15 GPa. A reversible phase transition from the monoclinic (B) to trigonal (A) phase has been observed for all compositions by Raman, with the transition pressure linearly increasing with x. The same conclusion was reached using the Eu3+ photoluminescence as a local probe. The fraction of B and A phases as a function of pressure has been estimated through the integrated intensity of the Eu3+ 5D0-7F0 electronic transition. The possibility of using the evolution of the spectral distribution of 5D0-7F2 transition to estimate the fraction of each phase with pressure has been also discussed. Moreover, the spectral shifts of 5D0-7F0 and 5D0-7F1 transitions with pressure have been used to evaluate the effect of pressure on the spin-orbit coupling constant ξ4f.