Red-emitting phosphor Na2Ca2Nb4O13:Eu3+ for LEDs: Synthesis and luminescence properties

Abstract

Na2Ca2Nb4O13:Eu3+ phosphor is successfully synthesize by the high-temperature solid-state reaction method in air. The crystal structures, morphology, X-ray powder diffractions (XRPD) patterns, energy dispersive X-ray (EDX) spectrum, decay curves, and luminescence properties are investigated. Na2Ca2Nb4O13:Eu3+ phosphor emits red light with the chromaticity coordinates (0.6312, 0.3684) and the emission spectrum is observed in the range of 575–725 nm, which contains four emission bands because of the 5D0 → 7F1 (575–600 nm), 5D0 → 7F2 (600–650 nm), 5D0 → 7F3 (650–670 nm), 5D0 → 7F4 (680–725 nm) transitions of Eu3+ ion, respectively. The optimal Eu3+ ion concentration in Na2Ca2Nb4O13:Eu3+ phosphor is ~10 mol%. The lifetime decreases in turn from 736.5 μs to 431.8 μs with increasing Eu3+ ion concentration from 2 mol% to 12 mol%. Na2Ca2Nb4O13:Eu3+ phosphor has a good thermal stability according to the temperature-dependent emission spectra. Luminous mechanism is explained by energy level diagram of Eu3+ ion. The experimental results indicate that Na2Ca2Nb4O13:Eu3+ phosphor has a hope to be used as red phosphor for light-emitting diodes (LEDs) based on near ultraviolet (UV) and blue LED chips.