Yb3+ rare earth structural probe and correlation between morphology and spectroscopic properties in La2Mo2O9. Comparative analysis with mixed cubic La2MoWO9 translucent ceramics

We present and discuss the structural and spectroscopic properties of micro-crystalline Yb3+-doped La2Mo2O9 molybdates (0-25 mol% of Yb3+ ions) synthesized by the high-temperature solid-state reaction in which Yb3 optical rare earth ion play the role of a structural probe. The main objective is to apply these materials to transparent optical ceramics. The XRD and SEM analysis reveal a strong structural dependence of the crystal structure on Yb3+ ion concentration. The high-resolution of the F-2(7/2) <-> F-2(5/2) O-phonon line of Yb3+ ions in absorption and emission spectroscopy at low temperature allows us to evidence three types of polyhedral around Yb3+ ions. Clear differences for cubic Yb3+-doped both La2Mo2O9 and mixed La2MoWO9 are observed as a result of the introduction of tungsten ions leading to greater disorder in the lattice. First translucent cubic ceramics have been successfully fabricated and the comparison turns out in favor of Yb3+-doped mixed La2MoWO9.