Synthesis, Crystal Structure, and Luminescence Properties of a White-Light-Emitting Nitride Phosphor, Ca_0.99Eu_0.01AlSi₄N₇

Abstract

Colorless transparent single crystals of a new europium-doped calcium aluminum silicon nitride, Ca 0.99 Eu 0.01 AlSi 4 N 7 , were synthesized by heating a mixture of binary nitrides (Ca 3 N 2 , EuN, AlN, Si 3 N 4 , and Mg 3 N 2 ) at 2150 °C under a nitrogen gas pressure of 0.85 MPa. The X-ray diffraction reflections from a single crystal were indexed with orthorhombic cell parameters a = 11.6819(3) Å, b = 21.0193(6) Å, and c = 4.91770(10) Å. The crystal structure was isomorphic to that of SrAlSi 4 N 7 :Eu (space group Pna2 1 ). One of the Ca/Eu sites was split into two sites of 4-fold and 8fold nitrogen coordination. A white-light emission spectrum with two peaks at wavelengths of 498 and 614 nm was observed from the single crystals under 400 nm near-ultraviolet-light irradiation. The CIE1931 chromaticity of the white light was plotted at x = 0.378 and y = 0.429; the mean color-rendering index Ra was 81.

Why Do Relative Intensities of Charge Transfer and Intra-4f Transitions of Eu3+ Ion Invert in Yttrium Germanate Hosts? Unravelling the Underlying Intricacies from Experimental and Theoretical Investigations

“…CT states affect the thermal quenching property of phosphor, especially for high-power LEDs, and that is why the thermal quenching property is one of the important technological parameters for phosphors used in solid-state lighting. − The CT state provides possible pathways for thermal quenching of Eu 3+ emission due to radiation-less relaxation by crossover . In the crossover process, an electron at the 5 D 0 state of Eu 3+ gets thermally activated and migrates to the CT state, then relaxes to another cross-point of CTB and 7 F J states subsequently hitting the ground state of Eu 3+ .…”

Development of sialon phosphors and their applications to solid-state lighting

“…Yoshimura et al reported a white-emitting CaAlSi 4 N 7 : Eu 2+ phosphor. Under 400 nm excitation, two emission bands centered at 498 and 614 nm are observed, respectively 42). There are three different crystallographic sites for Ca/Eu with N-atom coordination numbers of four, five and six.…”

All‐Inorganic Functional Phosphor–Glass Composites by Light Curing Induced 3D Printing for Next‐Generation Modular Lighting Devices

“…Rare-earth activated nitride phosphors are supposed to improve the problems of high CCT and low CRI of YAG:Cebased WLEDs because of wide excitation band and high conversion efficiency. [36,37] The abundant emission of Eu 2+ ions from blue to red has demonstrated the superiority of Eu 2+ in WLEDs devices. [38][39][40][41] CaAlSiN 3 :Eu (CASN:Eu) is one of these WLEDs with desirable chromaticity, high quantum efficiency, and matchable excitation wavelength, making it suitable WLEDs for both general lighting and wide color-gamut displays.…”