The compound Li3SiNO2:Eu2+ was synthesized in high temperature solid-state reactions in weld shut tantalum ampules and the crystal structure of Li3SiNO2 has been determined by single-crystal X-ray diffraction. It crystallizes...
Eu 2 + ) was synthesized by a hightemperature solid-state reaction. It is accessible from K 2 CO 3 , Li 2 O, SiO 2 , and an Eu-source (Eu 2 O 3 ) by conventional solid-state reaction in nickel crucibles under a constant flow of forming gas. The crystal structure of LKLSO has been determined by single-crystal X-ray diffraction and it crystallizes in the tetragonal space group I4 1 =a (no. 88) with the lattice parameters a = 1560.83(5), c = 1278.23(4) pm, and a volume of V = 0.31140(2) nm 3 . The compound is isostructural to NaK 7 [Li 3 SiO 4 ] 8 : Eu 2 + but, in contrast, features an enhanced suppression of the second broad band emission through the specific channel filling in the crystal structure. Despite the observed positional disorder in the structure, the cyan-green phosphor shows a narrow band emission with a maximum at 511 nm and a fwhm of 45 nm (0.215 eV).
Water absorbed to poly(methyl methacrylate) (PMMA)-based CAD/CAM (computer-assisted design/computer-assisted manufacturing) prosthodontics can alter their properties including hardness and stability. In the present contribution, water absorption and desorption kinetics under defined experimental conditions were monitored employing several supplementary and advanced Fourier transform infrared (FT-IR) spectroscopic techniques in combination with multivariate analysis (MVA). In this synergistic vibrational spectroscopic multimethod approach, first a novel near-infrared (NIR) diffuse fiber optic probe reflection spectroscopic method was established for time-resolved analysis of water uptake within seven days under controlled conditions. Near-infrared water absorbance spectra in a wavenumber range between 5288-5100 cm (combination band) and 5424-5352 cm (second overtone) were used establishing corresponding calibration and validation models to quantify the amount of water in the milligram range. Therefore, 14 well-defined samples exposed to prior optimized experimental conditions were taken into consideration. The average daily water uptake conducting reference analysis was calculated as 22 mg/day for one week. Additionally, in this study for the first time NIR two-dimensional correlation spectroscopy (2D-COS) was conducted to monitor and interpret the spectral dynamics of water absorption on the prosthodontics in a wavenumber range of 5100-5300 cm. For sensitive time-resolved recording of water desorption, a recently developed high-temperature, high-pressure FT-IR reaction cell with water-free ultra-dry in situ and operando operation was applied. The reaction cell, as well as the sample holder, was fully made of quartz glass, with no hot metal or ceramic parts in the vicinity of the high temperature zone. Applying a temperature gradient in the range of 25-150 ℃, mid-infrared (MIR) 2D-COS was successfully conducted to get insights into the dynamic behavior of O-H (1400-1800 cm) absorption bands with increasing temperature over time and the release of CO (2450 cm) from the polymers. In addition, an ATR FT-IR imaging setup was optimized in order to investigate the surface homogeneity of the PMMA-based resins with a spatial resolution to 2 µm. From this vibrational spectroscopic multimethod approach and the collection of several analytical data, conclusions were drawn as to which degree the surface structure and/or its porosity have an impact onto the amount of water absorption.
Building on studies of monoclinic Li3SiNO2, a polymorph, β-Li3SiNO2, with a previously unknown structure type was synthesized. The β-phase crystallizes in the orthorhombic space group Pbca (no. 61) with lattice...
AbstractThe isotypic triel borates Al5B12O25(OH) and Ga4InB12O25(OH) were synthesized in a Walker-type multianvil apparatus under high-pressure/high-temperature conditions of 12.0 GPa/1400 °C and 12.3 GPa/1200 °C, respectively. The crystal structures of both compounds, determined by single-crystal X-ray diffraction, constitute new representatives of the structure type M5B12O25(OH) (M = Ga, In) crystallizing in the space group I41/acd. The presence of the hydroxyl groups was confirmed via single-crystal IR spectroscopy.
The new compound Ba 4 Al 7 Li 28.08 O 26.92 N 1.08 consists of AlO 4 /AlO 3 N tetrahedra, 10-fold coordinated Ba 2+ cations, and a highly condensed edge-and corner-sharing LiO 4 tetrahedra framework, which leads to a degree of condensation greater than 1. The first barium oxonitridolithoaluminate was synthesized by a high-temperature solid-state reaction in a weld-shut tantalum ampoule and the crystal structure has been determined by single-crystal X-ray diffraction. Ba 4 Al 7 Li 28.08 O 26.92 N 1.08 crystallizes in the monoclinic space group P2 1 /m (no. 11) with the lattice parameters a = 1052.41(3), b = 615.93(2), c = 1088.45(4) pm, β = 98.86(1)°, and a volume of V = 0.69712(4) nm 3 . In addition, Ba 4 Al 7 Li 28.08 O 26.92 N 1.08 doped with the activator ion Eu 2+ , exhibits a broad band emission with a maximum at λ max = 524 nm (2.34 eV) with a fwhm of 112 nm (4373 cm −1 /0.54 eV), which can be described by a superposition of two adjusted emission bands at λ max = 515 nm (2.41 eV) with a fwhm of 70 nm (2704 cm −1 /0.34 eV), and at λ max = 574 nm (2.18 eV) with a fwhm of 127 nm (4127 cm −1 /0.51 eV).
Single-crystals of Li 2 Ba 4 Al 2 Ta 2 N 8 O:Eu 2 + were synthesized from Ba 3 N 2 , Al 2 O 3 , Li 3 N, Eu 2 O 3 , and lithium metal by a high-temperature solid-state reaction in a weld shut tantalum ampule. The crystal structure of Li 2 Ba 4 Al 2 Ta 2 N 8 O was determined by single-crystal X-ray diffraction and it crystallizes in the orthorhombic space group Pnnm (no. 58) with the lattice parameters a = 1006.71(3), b = 1026.58(3), c = 607.10(2) pm, and a volume of V = 0.62742(3) nm 3 . The compound is built up from AlN 4 and TaN 4 tetrahedra, which form a three-dimensional network corresponding to the BCT-zeolite type structure.
The isotypic trielborates c-Al 5 B 12 O 25 (OH), c-Al 1.7 Ga 3.3 B 12 O 25 (OH), and c-Ga 4 InB 12 O 25 (OH) were synthesized under high-pressure/ high-temperature conditions of � 12 GPa and � 1100°C. The three cubic compounds crystallize in the space group Fm � 3m with Z = 4 and a = 10.8226(5), 10.9258(5), and 11.176(2) Å for c-Al 5 B 12 O 25 (OH), c-Al 1.7 Ga 3.3 B 12 O 25 (OH), and c-Ga 4 InB 12 O 25 (OH), respectively. The crystal structures of all three compounds were determined by single-crystal X-ray diffraction revealing disordered cubic structures composed of MO 6 octahedra (M = Al, Al/ Ga, Ga, In) and BO 4 tetrahedra. Single-crystal Raman and IR spectroscopic data further characterize the compounds, and the latter confirms the presence of hydroxyl groups.
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