Oxonitridosilicate Oxides RE₂₆Ba₆[Si₂₂O₁₉N₃₆]O₁₆:Eu²⁺ (RE = Y, Tb) with a Unique Layered Structure and Orange-Red Luminescence for RE = Y

Abstract

T h e o x o n i t r i d o s i l i c a t e o x i d e s RE 26 Ba 6 [Si 22 O 19 N 36 ]O 16 :Eu 2+ (RE = Y, Tb) were synthesized by high-temperature reaction in a radiofrequency furnace starting from REF 3 , RE 2 O 3 (RE = Y, Tb), BaH 2 , Si(NH) 2 , and EuF 3 . The structure elucidation is based on single-crystal X-ray data. The isotypic materials crystallize in the monoclinic space group Pm (no. 6) [Z = 3, a = 16.4285(8), b = 20.8423(9), c = 16.9257(8) Å, β = 119.006(3)°for RE = Y and a = 16.5465(7), b = 20.9328(9), c = 17.0038(7) Å, β = 119.103(2)°for RE = Tb].The unique silicate layers are made up from Q 1 -, Q 2 -, and Q 3 -type Si(O/N) 4 -as well as Q 4type SiN 4 -tetrahedra, forming three slightly differing types of cages. The corresponding 3-fold superstructure as well as pronounced hexagonal pseudosymmetry complicated the structure elucidation. Rietveld refinement on powder X-ray diffraction data, energy-dispersive X-ray spectroscopy and infrared spectroscopy support the findings from single-crystal X-ray data. When excited with UV to blue light, Y 26 Ba 6 [Si 22 O 19 N 36 ]-O 16 :Eu 2+ shows broad orange-red luminescence (λ em = 628 nm, fwhm ≈ 125 nm/3130 cm −1 ). An optical band gap of 4.2 eV was determined for the doped compound by means of UV/vis spectroscopy.

RE4Ba2[Si12O2N16C3]:Eu2+ (RE = Lu, Y): Green-Yellow Emitting Oxonitridocarbidosilicates with a Highly Condensed Network Structure Unraveled through Synchrotron Microdiffraction

“…These are typical values for lutetium (oxo)­nitridosilicates. , The Ba–anion distances are rather large with values of 2.95(3)–3.06(3) Å for Ba–O and 2.80(2)–3.52(3) Å in the case of Ba–O/N. However, similar distances were reported for other barium (oxo)­nitridosilicates such as BaSi 7 N 10 (2.913(3)–3.529(3) Å), Ba 2 ­Si 5 N 8 (2.677(7)–3.171(4) Å), or Y 26 Ba 6 ­[Si 22 O 19 ­N 36 ]­O 16 :Eu 2+ (2.63(1)–3.59(2) Å) …”

MBe20N14:Eu2+ (M = Sr, Ba): Highly Condensed Nitridoberyllates with Exceptional Highly Energetic Eu2+ Luminescence

“…Generally, phosphors used in pc LEDs should meet certain requirements, like efficient absorption of UV or blue light from the primary LED, high chemical and thermal stability, small thermal quenching, and high conversion efficiency. ,,, Therefore, host lattices for efficient phosphors typically provide a wide band gap and a rigid host lattice with high atomic connectivity. By a targeted search for materials with a large band gap ( E g ) and high Debye temperature (θ D ) (which is used as a proxy for the rigidity of a host lattice), new inorganic phosphors could already be identified. − In the last decades, the field of suitable host lattices for doping with Eu 2+ has been significantly extended to a magnitude of intriguing (oxo)­nitridosilicates, − nitridoalumosilicates, − nitridomagnesosilicates, − nitridolitho- and nitridomagnesoaluminates, and quite recently also oxo­(nitrido)­beryllates. ,,− Since compounds such as (Sr,Ca)­AlSiN 3 :Eu 2+ , (Ba,Sr) 2 Si 5 N 8 :Eu 2+ , and Sr­[LiAl 3 N 4 ]:Eu 2+ already have been commercially used, ,, Eu 2+ -doped nitrides have proven their huge potential. In contrast to nitridosilicates (degree of condensation κ = n (Si): n (N) ≤ 0.75) or nitridoaluminates (κ ≤ 1.0), oxo­(nitrido)­beryllates can reach exceptionally high degrees of condensation (maximum κ = 1.0 in BeO and 1.5 in Be 3 N 2 ).…”

Development of a novel Eu2+ activated oxonitridosilicate cyan phosphor for enhancing the color quality of a violet-chip-based white LED

“…On the basis of the advantages mentioned above, (oxo)nitridosilicate phosphors are considered as promising candidate materials for phosphor-converted white LEDs. [31][32][33][34][35][36][37] For example, Ce 3+ and Eu 2+ -doped La 3 Si 8 O 4 N 11 oxonitridosilicate phosphors have been reported successively. 38,39 In 2001, a new Al-containing oxonitridosilicate with the formula of La 3 Si 6.5 Al 1.5 N 9.5 O 5.5 (LSANO) was established by Grins et al 40 Then Wang et al studied the PL properties of Ce 3+ activated LSANO compounds, which exhibit blue emission with a peak value of 450 nm.…”