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

Abstract

The oxonitridocarbidosilicates RE 4Ba2­[Si12O2­N16C3]:­Eu2+ (RE = Lu, Y) were synthesized by carbothermal reactions starting from RE 2O3, graphite, Ba2­Si5N8, Si­(NH)2, and Eu2O3. The crystal structure of Lu4Ba2­[Si12O2­N16C3]:­Eu2+ was elucidated on a submicron-sized single crystal by a combination of transmission electron microscopy and microfocused synchrotron radiation. The compound crystallizes in trigonal space group P3 (no. 143) with a = 16.297(4) Å, c = 6.001(2) Å, and Z = 3 (R1 = 0.0332, wR2 = 0.0834, GoF = 1.034). According to Rietveld refinements on powder X-ray diffraction data, Y4Ba2­[Si12O2­N16C3]:­Eu2+ is isotypic with a = 16.41190(6) Å and c = 6.03909(3) Å. The crystal structures are built up of vertex-sharing SiC­(O/N)3 tetrahedra forming star-shaped units [C[4]­(Si­(O/N)3)4] with carbon atoms in fourfold bridging positions. Energy-dispersive X-ray spectroscopy and CHNS analysis correspond to the sum formula, lattice energy, and charge distribution calculations support the assignment of O/N/C atoms. When excited with UV to blue light, Eu2+-doped samples show green luminescence for RE = Lu (λem ≈ 538 nm, full width at half-maximum (fwhm) ≈ 3600 cm–1) and yellow emission in the case of RE = Y (λem ≈ 556 nm, fwhm ≈ 4085 cm–1).

Structure Elucidation of Complex Endotaxially Intergrown Lanthanum Barium Oxonitridosilicate Oxides by Combination of Microfocused Synchrotron Radiation and Transmission Electron Microscopy

“…For all three compounds discussed, interatomic distances within the Si−N/O tetrahedra, O−La/Ba and O−La/Sr distances as well as the cation coordination polyhedra with the corresponding distances are listed in Tables S15–18 and agree well with those reported for other (oxo‐)nitridosilicates. [ 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 ]…”

Missing Member in the MIIMIIISi4N7 Compound Class: Carbothermal Reduction and Nitridation Synthesis Reveal Substitution of Nitrogen by Carbon and Oxygen in CaLu[Si4N7–2xCxOx]:Eu2+/Ce3+ (x≈0.3)

“…This makes CaLu[Si 4 N 7–2 x C x O x ] the first oxonitridocarbidosilicate in this compound class and just the second oxonitridocarbidosilicate besides RE 4 Ba 2 [Si 12 O 2 N 16 C 3 ]:Eu 2+ ( RE =Lu, Y) known so far. [21] Additional luminescence investigations reveal emission in the yellow‐green and blue spectral regions upon doping with either Eu 2+ or Ce 3+ , respectively.…”

Ammonothermal Synthesis and Crystal Growth of the Chain‐type Oxonitridosilicate Ca1+xY1–xSiN3–xOx (x > 0)

“…Typically, these materials are synthesized via high‐temperature reactions in radio‐frequency furnaces, tantalum ampules or tube furnaces . In doing so, various synthesis routes like metathesis reactions or the carbothermal approach were employed accessing new compounds like RE 4 Ba 2 [Si 9 ON 16 ]O:Eu 2+ , La 3 BaSi 5 N 9 O 2 :Ce 3+ or RE 4 Ba 2 [Si 12 O 2 N 16 C 3 ]:Eu 2+ ( RE = Lu, Y) . However, the growth of large single crystals of (oxo)nitridosilicates, which is inevitable for numerous applications, is quite challenging.…”

“…[1] In doing so, various synthesis routes like metathesis reactions or the carbothermal approach were employed accessing new compounds like 2+ (RE = Lu, Y). [4][5][6] However, the growth of large single crystals of (oxo)nitridosilicates, which is inevitable for numerous applications, is quite challenging.…”