Tunable Photoluminescence and Energy Transfer Efficiency in β-Ca 3 (PO 4 ) 2 -Ca 9 La(PO 4 ) 7 :Eu 2+ , Mn 2+ Solid Solution Phosphors Introduced by Emptying Site and Structural Confinement Effect for Solid-State Lighting Application

Full visible emission achieved by a single-phased system is of great interest to researchers for the development of high-quality solid-state lighting devices. Herein, novel Eu and Mn co-doped (1 - )β-Ca (PO ) - Ca La(PO ) solid solution phosphors are designed to realize single-phased white light emission. The effects of variational on lattice structure, color-tunable emission, thermal stability, and energy-transfer efficiency from Eu to Mn are systematically investigated. Tunable color emissions are achieved by manipulating the redistributions of Eu ions among the different cationic sites under the influence of generated empty site in the M(4) site. Meanwhile, the changes of critical distances among the Eu and Mn caused by the variational results in the changes of energy-transfer efficiency from different Eu luminescent centers to Mn due to the existence of structural confinement effect. The calculated results indicate that Eu1-Mn and Eu2-Mn possess higher energy-transfer efficiencies than other Eu-Mn pairs. Under the combined influence of the two effects, single-phased full visible white emission covering from 400 to 700 nm has been realized via the adjustment of solid solution, which makes the fabricated white-light-emitting diode (WLED) possess high color-rendering index (86.9) and R9 (87.2) as well as low correlated color temperature (3947 K). The results show that the 0.2β-Ca (PO ) -0.8Ca La(PO ) :0.01Eu , 0.20Mn could act as a promising phosphor for single-phased WLEDs. This work will open up a new avenue for tuning the multiple activator sites and energy-transfer efficiencies simultaneously to realize single-phased full visible white emission.