Efficient Yellow-Orange Phosphor Lu₄Ba₂[Si₉ON₁₆]O:Eu²⁺ and Orange-Red Emitting Y₄Ba₂[Si₉ON₁₆]O:Eu²⁺: Two Oxonitridosilicate Oxides with Outstanding Structural Variety

Abstract

The oxonitridosilicate oxides Y4Ba2[Si9ON16]­O:Eu2+ and Lu4Ba2[Si9ON16]­O:Eu2+ have been synthesized starting from REF3, RE 2O3 (RE = Y, Lu), BaH2, Si­(NH)2, and EuF3 in a radiofrequency furnace at 1550 °C. The crystal structures were solved and refined from single-crystal X-ray data supported with Rietveld refinement on X-ray powder diffraction data. Both compounds are isotypic and crystallize in monoclinic space group P21/c (no. 14) with Z = 4 and a = 6.0756(2), b = 27.0606(9), c = 9.9471(3) Å, and β = 91.0008(8)° for RE = Y and a = 6.0290(3), b = 26.7385(12), c = 9.8503(5) Å, and β = 90.7270(30)° for RE = Lu. The unique crystal structure exhibits a three-dimensional network made up from Q4-type SiN4 and Q3-type SiON3 tetrahedra. Containing 4-fold bridging N[4] atoms in star-shaped units [N[4](SiN3)4] next to N[3], N[2], O[1], and noncondensed oxide ions, the title compounds illustrate the vast structural variety in (oxo)­nitridosilicates. Under excitation with UV to blue light, Y4Ba2[Si9ON16]­O:Eu2+ shows emission in the orange-red spectral range (λmax = 622 nm, full width at half-maximum (fwhm) ≈ 2875 cm–1). Yellow-orange emitting Lu4Ba2[Si9ON16]­O:Eu2+ (λmax = 586 nm, fwhm ≈ 2530 cm–1) exhibits high internal quantum efficiency (IQE) ≈ 85%. This makes Lu4Ba2[Si9ON16]­O:Eu2+ a promising phosphor for low color rendering index (CRI) warm white phosphor converted light emitting diodes (pcLEDs).

Oxoberyllates SrBeO2 and Sr12Be17O29 as Novel Host Materials for Eu2+ Luminescence

“…This BeO polymorph is predicted at very high pressures and temperatures: four BeO 4 ‐tetrahedra are connected by one common oxygen forming star‐shaped [O(BeO 3 ) 4 ] units. In highly condensed silicate structures containing X ( X =O,N), only N, connecting four SiN 4 tetrahedra, is known . In Ca 12 Be 17 O 29 , these star‐shaped units are isolated, but stabilized by four capping Be atoms, forming BeO 3 ‐units.…”

“…In highly condensed silicates tructures containing X [4] (X = O,N), only N [4] ,c onnecting four SiN 4 tetrahedra, is known. [23][24][25][26] Figure 4. The arrangement of strands can be described as closest packing, where strands are separated by Sr-atoms in sevenand eightfold O-coordination, respectively,w ith SrÀOd istances between 2.50 and 2.79 .B e ÀOd istances are inarange of 1.58-1.71 ,c omparable to the values found for the regular tetrahedrally-coordinated Be sites in Ca 12 Be 17 O 29 .…”

Ammonothermal Synthesis of Nitrides: Recent Developments and Future Perspectives

“…For instance, various rare earth doped oxonitridosilicates possess excellent photoluminescence properties for possible application in light emitting diodes,w hereas several novel oxonitridophosphates with unprecedented crystal structures were reported in recent years. [141][142][143][144] Inclusion of oxygen containing precursors in ammonothermal syntheses enables access to oxonitride materials as well. Previous studies focused on synthesis of oxonitrides with compositions LnTaON 2 (Ln = La, Pr,N d, Sm, Ce, Gd), LaNbON 2 ,a nd BaTaO 2 Nw hich all crystallize in the perovskite structure type (see Table 3).…”

Y23Sr17[Si38O18N67]O9 – An Oxonitridosilicate Oxide with a Unique Layered Structure

“…Presumably, the driving force of these reactions is the formation of stable binary compounds AE F 2 as well as H 2 , leading to the desired (oxo)nitridosilicates. If an excess of AE H 2 is provided during synthesis, RE/AE /Si/O/N compounds with fascinating crystal structures and luminescence properties, such as La 3 BaSi 5 N 9 O 2 :Ce 3+ , Lu 4 Ba 2 [Si 9 ON 16 ]O:Eu 2+ or La 3– x Ca 1.5 x Si 6 N 11 :Eu 2+ ( x ≈ 0.77) are obtained …”