(INVITED)Laser-driven white light with tunable low-colour temperature based on novel ZrO2-doped (Gd,Lu)2O3:Eu red-emitting transparent ceramics

Abstract

Novel red-emitting ZrO2-doped (Gd,Lu)2O3:Eu transparent fluorescent ceramics were fabricated via a vacuum sintering method. The f–f transitions of Eu3+ in the ZrO2-doped (Gd,Lu)2O3:Eu transparent fluorescent ceramics have much higher intensity than the charge-transfer band (CTB) excitation, hence can be efficiently excited with near-UV light and blue light for white LED applications. The YAG:Ce phosphor was used to prepare a coating on the surface of the transparent ceramics to prepare (Gd,Lu)2O3:Eu/YAG:Ce ceramic laminates as colour converters. XRD, SEM, UV–vis–NIR spectroscopy and PLE/PL were used to characterize the properties of the resultant phosphors, transparent ceramics and colour converters. The results showed that for the (Gd,Lu)2O3:Eu transparent ceramic, an appropriate reduction of the sintering temperature and time would reduce its optical transmittance while enhancing the red emission. Under the excitation of 465 nm laser light, the (Gd,Lu)2O3:Eu/YAG:Ce ceramic converter could generate ideal white light at various low colour temperatures, effectively making up for the deficiency of the low colour rendering index and high colour temperature caused by the lack of red light components in the solid-state lighting. The ceramic converters may have potential applications in laser lighting.