Color Tuning of Direct White Light of Lanthanum Aluminate with Mixed-Valence Europium

The generation of direct white-light emission of the coexisting valence-varied europium lanthanum aluminate through substitution of cations into the host and its resultant adjustment of the energy transfer have been presented. With respect to La0.99-xSrxAlO3-delta: Eu-0.01 and La0.994Al1-xO3-delta: Eu-0.006, and Mn-x, Li-0.012, the green-light emission positioned at 515 nm plays a key role to color mix for white light and can be efficiently tuned by adjusting the transfer of energy and relevant transition emissions between the luminous centers of Eu2+ and Eu3+/Mn2+, via varying amounts of dopants. Direct white-light emission with optimized values of 86 for the color rendering index and 5091 K for the correlated color temperature has been achieved for lanthanum aluminate by this mixed-valence means.