Tunable emission from silico-carnotite type double silicates doped with Tb^3+ and Eu^3+

Double silicates with the silico-carnotite orthorhombic structure and co-doped with Tb3+ and Eu3+ have been prepared by solid-state reaction. Room temperature luminescence spectra and decay kinetics have been measured and analysed. Upon UV excitation at 378 nm, the emission colour varies from red to pinkish, depending on the doping level. The resulting colour can be adjusted by controlling the Tb3+/Eu3+ concentration ratio. Control of the doping leads to close-to-white emission in some of the analysed samples upon excitation in the wavelength region useful for LED lighting