An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Abstract Isotypic MH 4 P 6 N 12 (M: Mg, Ca) compounds are prepared by high‐pressure/high‐temperature reactions of stoichiometric amounts of M 3 N 2 , HPN 2 , and P 3 N 5 (multi‐anvil press, 8 GPa, 1000 °C, 2 h).
Nanoscale zinc-oxide doped with aluminum ZnO:Al is studied by different techniques targeting surface changes induced by the conditions at which ZnO:Al is used as support material in the catalysis of methanol. While it is well established that a variety of
Abstract Isotypic imidonitridophosphates M H 4 P 6 N 12 ( M =Mg, Ca) have been synthesized by high‐pressure/high‐temperature reactions at 8 GPa and 1000 °C starting from stoichiometric amounts of the respective alkaline‐earth metal nitrides, P 3 N 5 , and amorphous HPN 2 . Both compounds form colorless transparent platelet crystals. The crystal structures have been solved and refined from single‐crystal X‐ray diffraction data. Rietveld refinement confirmed the accuracy of the structure determination. In order to quantify the amounts of H atoms in the respective compounds, quantitative solid‐state 1 H NMR measurements were carried out. EDX spectroscopy confirmed the chemical compositions. FTIR spectra confirmed the presence of NH groups in both structures. The crystal structures reveal an unprecedented layered tetrahedral arrangement, built up from all‐side vertex‐sharing PN 4 tetrahedra with condensed dreier and sechser rings. The resulting layers are separated by metal atoms.
In NMR, paramagnetic dopants change the relaxation behavior and the chemical shift of the nuclei in their immediate environment. Based on the concept that the "immediate environment" in a diamagnetic host material can be described as a sphere with radius r0, we developed a function for the fraction of unperturbed nuclei (the fraction of nuclei outside the sphere) which gives a link between the effective radius and the doping concentration. In the case of a homogeneous doping scenario a characteristic dependence is observed in both theory and experiment. We validated the model on a sample series where paramagnetic Eu(II) ions are doped into crystalline SrH2. The fraction of unperturbed nuclei was determined from the (1)H NMR signal and follows the predicted curve for a homogeneous doping scenario where the radius r0 is 17 Å.
Abstract The first crystalline phosphorus oxonitride imide H 3 P 8 O 8 N 9 (=P 8 O 8 N 6 (NH) 3 ) has been synthesized under high‐pressure and high‐temperature conditions. To this end, a new, highly reactive phosphorus oxonitride imide precursor compound was prepared and treated at 12 GPa and 750 °C by using a multianvil assembly. H 3 P 8 O 8 N 9 was obtained as a colorless, microcrystalline solid. The crystal structure of H 3 P 8 O 8 N 9 was solved ab initio by powder X‐ray diffraction analysis, applying the charge‐flipping algorithm, and refined by the Rietveld method ( C 2/ c (no. 15), a =1352.11(7), b =479.83(3), c =1820.42(9) pm, β =96.955(4)°, Z =4). H 3 P 8 O 8 N 9 exhibits a highly condensed ( κ =0.47), 3D, but interrupted network that is composed of all‐side vertex‐sharing (Q 4 ) and only threefold‐linking (Q 3 ) P(O,N) 4 tetrahedra in a Q 4 /Q 3 ratio of 3:1. The structure, which includes 4‐ring assemblies as the smallest ring size, can be subdivided into alternating open‐branched zweier double layers {oB, ${2{{2\hfill \atop \infty \hfill}}}$ }[ 2 P 3 (O,N) 7 ] and layers containing pairwise‐linked Q 3 tetrahedra parallel (001). Information on the hydrogen atoms in H 3 P 8 O 8 N 9 was obtained by 1D 1 H MAS, 2D homo‐ and heteronuclear (together with 31 P) correlation NMR spectroscopy, and a 1 H spin‐diffusion experiment with a hard‐pulse sequence designed for selective excitation of a single peak. Two hydrogen sites with a multiplicity ratio of 2:1 were identified and thus the formula of H 3 P 8 O 8 N 9 was unambiguously determined. The protons were assigned to Wyckoff positions 8 f and 4 e , the latter located within the Q 3 tetrahedra layers.
Abstract The title phosphor (2 mol% Eu) is synthesized from a stoichiometric mixture of (Sr 0.5 Ba 0.5 ) 2 SiO 4 :Eu and α‐Si 4 N 4 in 5% H 2 /N 2 (1450 °C, 5 h) and characterized by powder XRD, SAED, and luminescence spectroscopy.
The mechanisms by which amorphous intermediates transform into crystalline materials are still poorly understood. Here we attempt to illuminate the formation of an amorphous precursor by investigating the crystallization process of zinc phosphate hydrate. This work shows that amorphous zinc phosphate (AZP) nanoparticles precipitate from aqueous solutions prior to the crystalline hopeite phase at low concentrations and in the absence of additives at room temperature. AZP nanoparticles are thermally stable against crystallization even at 400 °C (resulting in a high temperature AZP), but they crystallize rapidly in the presence of water if the reaction is not interrupted. X-ray powder diffraction with high-energy synchrotron radiation, scanning and transmission electron microscopy, selected area electron diffraction, and small-angle X-ray scattering showed the particle size (≈20 nm) and confirmed the noncrystallinity of the nanoparticle intermediates. Energy dispersive X-ray, infrared, and Raman spectroscopy, inductively coupled plasma mass spectrometry, and optical emission spectrometry as well as thermal analysis were used for further compositional characterization of the as synthesized nanomaterial. (1)H solid-state NMR allowed the quantification of the hydrogen content, while an analysis of (31)P{(1)H} C rotational echo double resonance spectra permitted a dynamic and structural analysis of the crystallization pathway to hopeite.
