Structure evolution and photoluminescence of Lu-3(Al,Mg)(2)(Al,Si)(3)O-12:Ce3+ phosphors: new yellow-color converters for blue LED-driven solid state lighting

This paper reports the development of new phosphors using the chemical unit cosubstituting solid solution design strategy. Starting from Lu3Al5O12, the Al3+-Al3+ couple in respective octahedral and tetrahedral coordination was simultaneously substituted by a Mg2+-Si4+ pair forming the Lu-3(Al2-xMgx)(Al3-xSix)O-12:Ce3+ (x = 0.5-2.0) series; as a result, the CeO8 polyhedrons were compressed and the emission got red-shifted from green to yellow together with the broadening. The evolution of, the unit cell, the local structural geometry as well as the optical properties of Ce3+ in these garnet creations, in response to the gradual Mg-Si substitution for Al-Al, were studied by combined techniques of structural refinement and luminescence measurements. The new composition Lu2.97Ce0.03Mg0.5Al4Si0.5O12 was comprehensively evaluated regarding its potential application in blue LED-driven solid state white lighting: the maximum emission is at 550 nm under lambda(ex) = 450 nm; the internal and external quantum efficiencies can reach 85% and 49%, respectively; a 1-phosphor-converted wLED lamp fabricated using the as-prepared phosphor exhibits the luminous efficacy of 105 lm W-1, the correlated color temperature of 6164 K and the color rendering index (R-a) of 75.6. The new solid solution composition series is open for further optimization to enhance the competence for commercial consideration.