To facilitate the next generation of high-power white-light-emitting diodes (white LEDs), the discovery of more efficient red-emitting phosphor materials is essential. In this regard, the hardly explored compound class of nitridoaluminates affords a new material with superior luminescence properties. Doped with Eu(2+), Sr[LiAl3N4] emerged as a new high-performance narrow-band red-emitting phosphor material, which can efficiently be excited by GaN-based blue LEDs. Owing to the highly efficient red emission at λ(max) ~ 650 nm with a full-width at half-maximum of ~1,180 cm(-1) (~50 nm) that shows only very low thermal quenching (>95% relative to the quantum efficiency at 200 °C), a prototype phosphor-converted LED (pc-LED), employing Sr[LiAl3N4]:Eu(2+) as the red-emitting component, already shows an increase of 14% in luminous efficacy compared with a commercially available high colour rendering index (CRI) LED, together with an excellent colour rendition (R(a)8 = 91, R9 = 57). Therefore, we predict great potential for industrial applications in high-power white pc-LEDs.

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Group (III) Nitrides M[Mg 2Al2N4] (M: Ca, Sr, Ba, Eu) and Ba[Mg2Ga2N4]-Structural Relation and Nontypical Luminescence Properties of Eu 2+ Doped Samples. -The new compounds (V), (VIII), and (X) are characterized by powder and single crystal XRD, SEM, UV/VIS spectroscopy, and luminescence spectroscopy. All the compounds crystallize in space group I4/m with Z = 2 (UCr 4C4-type structure), forming highly condensed anionic networks of disordered (Al/Mg)N 4 and (Ga/Mg)N4 units, connected to each other by common edges and corners. M 2+ (M: Ca, Sr, Ba, Eu) is centered in vierer ring channels and cuboid-like coordinated by N. Eu 2+ doped samples of (VIIIa-c) exhibit nontypical luminescence properties including trapped exciton emission in the red spectral region. -(PUST, P.; HINTZE, F.; HECHT, C.; WEILER, V.; LOCHER, A.; ZITNANSKA, D.; HARM, S.; WIECHERT, D.; SCHMIDT, P. J.; SCHNICK*, W.; Chem. Mater. 26 (2014) 21, 6113-6119,

Ca­[LiAl3N4]:Eu2+ is an intriguing new narrow-band red-emitting phosphor material with potential for application in high-power phosphor-converted light-emitting diodes (pc-LEDs). With excitation by blue InGaN-based LEDs, the compound exhibits an emission maximum at 668 nm with a full width at half maximum of only 1333 cm–1 (∼60 nm). Ca­[LiAl3N4]:Eu2+ was synthesized from Ca, LiAlH4, LiN3, AlF3, and EuF3 in weld-shut Ta ampules, and the structure was solved and refined on the basis of single-crystal X-ray diffraction data. After isotypical crystallization with Na­[Li3SiO4], the compound forms a highly condensed framework of AlN4 and LiN4 tetrahedra [I41/a (no. 88), Z = 16, a = 11.1600(16) Å, and c = 12.865(3) Å] and can thus by classified as a nitridolithoaluminate. Both types of polyhedra are connected to each other by common edges and corners, yielding a high degree of condensation, κ = 1. The Ca site is positioned in the center of vierer ring channels along [001] and coordinated in a cuboidal manner by eight N atoms. To validate the presence of Li, transmission electron microscopy (TEM) investigations employing electron energy-loss spectroscopy (EELS) were carried out. Furthermore, to confirm the electrostatic bonding interactions and the chemical composition, lattice energy calculations [Madelung part of lattice energy (MAPLE)] have been performed.

Rare‐earth fluorides are a class of materials with considerable potential in optical applications. Fluoride lattices typically permit high coordination numbers for the hosted rare‐earth ions, and the high ionicity of the rare‐earth‐to‐fluorine bond leads to a wide bandgap and very low vibrational energies. These factors make rare‐earth fluorides very useful in optical applications employing vacuum ultraviolet and near‐infrared excitation. The preparation of nanometer‐sized particles has opened the door for new properties and devices if the performance of their macroscopic counterparts can be conserved in the nanometer regime. However, at small particle sizes, defect surface states and adhering water reduce the optical efficiency. These shortcomings can be reduced by applying protective shells around the luminescent cores, which can also be involved in the luminescent process.