The new narrow-band red-emitting phosphor material Sr 4 [LiAl 11 N 14 ]:Eu 2+ was synthesized by solid-state reaction using a tungsten crucible with a cover plate in a tube furnace. When excited with blue light (460 nm), it exhibits red fluorescence with an emission maximum at 670 nm and a full width at half-maximum of 1880 cm −1 (∼85 nm). The crystal structure was solved and refined from single-crystal X-ray diffraction data. This new compound from the group of the nitridolithoaluminates crystallizes in the orthorhombic space group Pnnm (No. 58) with the following unit-cell parameters: a = 10.4291(7) Å, b = 10.4309(7) Å, and c = 3.2349(2) Å. Sr 4 [LiAl 11 N 14 ]:Eu 2+ shows a pronounced tetragonal pseudo-symmetry. It consists of a framework of disordered (Al/ Li)N 4 and AlN 4 tetrahedra that are connected to each other by common corners and edges. Along the [001] direction, the tetrahedral network creates empty four-memberedring channels as well as five-membered-ring channels, in which the Sr 2+ cations are located.
The high-pressure ammonium triborate HP-(NH 4 )B 3 O 5 was synthesized in a high-pressure/high-temperature experiment at 3 GPa and 600°C. It crystalizes in the monoclinic space group C2/c (No. 15) with the parameters a = 981.0(2), b = 880.2(2), c = 922.2(2) pm, β = 103.8(1)°, V = 0.7735(3) nm 3 , Z = 8, R 1 = 0.0436, and wR 2 = 0.1059 (all data). The compound is built up from ribbons of interconnected corner-and edge-sharing BO 4 tetrahedra that are linked by planar 2753 groups to form a three-dimensional structure. The ammonium ions are situated in channels, forming four hydrogen bonds to oxygen of the boron oxygen network. The structure is a substitutional variant of the compounds HP-MB 3 O 5 , (M = K, Rb) and HP-Cs 1-x (H 3 O) x B 3 O 5 (x = 0.5-0.7). The collected IR and Raman spectra of HP-(NH 4 )B 3 O 5 show great similarities to the spectra of the analogous phases.through single-crystal X-ray diffraction, IR and Raman spectroscopy. Results and Discussion Crystal StructureThe structure of HP-(NH 4 )B 3 O 5 is depicted in Figure 1 exhibiting great similarities to HP-MB 3 O 5 (M = K, Rb) [3,4] and HP-Cs 1-x (H 3 O) x B 3 O 5 (x = 0.5-0.7) [6] due to a similar boron
The isotypic series of the oxonitridosilicates RE 3 [Si 5 N 9 O] (RE = Dy-Er, Yb) was synthesized via solid-state reactions at high temperatures using a radio-frequency furnace. The crystal structures were solved and refined from single-crystal X-ray diffraction and powder X-ray diffraction data. Further characterizations were performed using vibrational spectroscopy (IR and Raman), REM-EDX measurements, lattice energy calculations (MAPLE), charge distribution (CHARDI), and bondvalence sum calculations (BVS). The compounds RE 3 [Si 5 N 9 O] (RE = Dy-Er, Yb) crystallize in the orthorhombic space group [a] 731 Pbcm (no. 57) (Z = 4) with the following lattice parameters: Dy 3 [Si 5 N 9 O]: a = 4.9865(3), b = 16.1633(9), and c = 10.6651(6) Å; Ho 3 [Si 5 N 9 O]: a = 4.9758(3), b = 16.1332(7), and c = 10.6312(5) Å; Er 3 [Si 5 N 9 O]: a = 4.9682(2), b = 16.1029(5), and c = 10.5995(3) Å; Yb 3 [Si 5 N 9 O]: a = 4.9473(2), b = 16.0622(5), and c = 10.5431(4) Å.The four isotypic compounds consist of a network of corner sharing SiN 4 and SiN 3 O tetrahedra. N [2] and N [3] interconnecting nitrogen atoms build five-membered rings, hosting the rare earth cations.These structural properties lead to rigid arrangements, which make nitrogen-containing silicates interesting compounds for hosting activator ions towards luminescent materials for the application in pc-LEDs, e.g., in M 3 [Si 6 N 2 O 12 ]:Eu 2+ (M = Ba, Sr), [13] Ba 2 [Si 5 N 8 ]:Eu 2+ , [14] Sr[Mg 3 SiN 4 ]:Eu 2+ , [15] Lu 4 Ba 2 [Si 9 N 16 O]O:Eu 2+ , and Y 4 Ba 2 [Si 9 N 16 O]O:Eu 2+ . [12] A large number of oxonitridosilicates also form structures solely with rare earth cations, such as
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