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Wagatha, Peter; Weiler, Volker; Schmidt, Peter J.; Schnick, Wolfgang (2018): Tailoring Emission Characteristics: Narrow-Band Red Luminescence from SLA to CaBa[Li(2)A(16)N(8)]:Eu2+. In: Chemistry of Materials, Vol. 30, No. 21: pp. 7885-7891
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Abstract

Narrow-band red-emitting luminescent CaBa[Li(2)A(16)N(8)]:Eu2+ for potential application in illumination-grade white-light-emitting diodes (WLEDs) was synthesized by reaction of the metal hydrides and nitrides in molybdenum crucibles in a hot isostatic press. Upon irradiation with high-energy visible light (444 nm), the material exhibits intense red and infrared luminescence (emission maxima, 636-639 nm, 790 nm;full width at half-maximum (fwhm), 1095-1266 cm(-1) (48-57 nm), approximate to 1450 cm(-1) (89 nm)). The red emission from Eu occupying the Ba site is nearly optimal for use in WLEDs combining outstanding color rendition and excellent luminous efficacy and the most narrow-band Eu2+ emission observed to date. The infrared emission intensity from Eu occupying the Ca site can be limited by reducing the activator concentration (here, 0.02-5 atom % Eu). CaBa[Li(2)A(16)N(8)]:Eu2+ crystallizes isotypically with RbNaLi6Si2O8 in the monoclinic space group C2/m (no. 12) with unit cell parameters a = 16.0851(2), b = 6.467 38(4), c = 8.042 42(13) angstrom, beta = 90.004(2)degrees, and Z = 4. The material is obtained almost phase pure with < 4 wt % AIN as side phase. The crystal structure consists of a network of vertex-and edge-sharing AlN4 and LiN4 tetrahedra with differently sized four-membered ring channels along [010] occupied by either cubelike coordinated Ca or Ba atoms or left empty.