Bistable luminescence of trivalent rare-earth ions in crystals

In this work, we have examined three new bistable systems based on the luminescence of three different crystals activated with trivalent rare earth ions. We have focussed our attention on Yb3+ ions activators, for which the most relevant results are obtained. The first crystal, Sr0.6Ba0.4Nb2O6, is a ferroelectric material with a relatively low phase transition temperature (∼370 K), which provides bistability in the luminescence of Yb3+ ions due to the thermal hysteresis associated with phase transition. The second crystal, LiNbO3, provides an intrinsic bistability in the luminescence of Yb3+ ions, which is driven by changes in the excitation intensity. In the third crystal, NdPO4, a new mechanism of excitation intensity driven bistability is obtained when activated with Yb3+ ions, due to a interplay between the Nd3+↔Yb3+ energy transfer and back transfer processes.