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 La(0.99-x)Sr(x)AlO(3-delta):Eu(0.01) and La(0.994)Al(1-x)O(3-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 Eu(2+) and Eu(3+)/Mn(2+), 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.