Energy transfer from Ce3+ to Tb3+ ions under UV excitation, giving rise to visible emissions, is investigated in sol–gel derived transparent nano-glass–ceramics containing cubic KYF4 nanocrystals, for different doping concentrations of rare-earth ions. Moreover, visible emissions of Tb3+ are also obtained under near-infrared excitation through energy transfer from Yb3+ ions by means of cooperative up-conversion processes. Thus, Ce3+–Tb3+–Yb3+ doped nano-glass–ceramics can be activated in a dual-wavelength mode yielding efficient blue–green emissions of particular interest in photovoltaic silicon solar cells and white-light emitting diodes
