Characterization of the Binary Nitrides VN and ScN by Solid-State NMR Spectroscopy

NMR spectra of polycrystalline samples of the binary nitrides ScN and VN were acquired under magic-angle spinning. The observed nuclides Sc-45, V-51 and N-14 are all quadrupolar nuclei with a spin I>1/2 ${I\char62 1/2}$ . However, due to the high symmetry of their rock-salt type structures, the spectra of the nitrides do not exhibit effects of quadrupolar or other anisotropic interactions of significant magnitude. This allows a relatively straightforward evaluation of the acquired spectra, leading to isotropic chemical shift values (delta(iso)) of -213 ppm ((VN)-V-51), 378 ppm ((VN)-N-14), 290 ppm ((ScN)-Sc-45) and 442 ppm ((ScN)-N-14) against commonly used reference standards. In the wider context of N-14-NMR of binary nitrides, it is shown that the distance of nitrogen to the nearest neighbour cation can be correlated to the observed chemical shift

Characterisation of contact twinning for cerussite, PbCO3, by single-crystal NMR spectroscopy

<jats:title>Abstract</jats:title><jats:p>Cerussite, <jats:inline-formula><jats:alternatives><jats:tex-math>$$\\hbox {PbCO}_3$$</jats:tex-math><mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:msub> <mml:mtext>PbCO</mml:mtext> <mml:mn>3</mml:mn> </mml:msub> </mml:math></jats:alternatives></jats:inline-formula>, like all members of the aragonite group, shows a tendency to form twins, due to high pseudo-symmetry within the crystal structure. We here demonstrate that the twin law of a cerussite contact twin may be established using only <jats:inline-formula><jats:alternatives><jats:tex-math>$$^{207}$$</jats:tex-math><mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:msup> <mml:mrow /> <mml:mn>207</mml:mn> </mml:msup> </mml:math></jats:alternatives></jats:inline-formula>Pb-NMR spectroscopy. This is achieved by a global fit of several sets of orientation-dependent spectra acquired from the twin specimen, allowing to determine the relative orientation of the twin domains. Also, the full <jats:inline-formula><jats:alternatives><jats:tex-math>$$^{207}$$</jats:tex-math><mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:msup> <mml:mrow /> <mml:mn>207</mml:mn> </mml:msup> </mml:math></jats:alternatives></jats:inline-formula>Pb chemical shift tensor in cerussite at room temperature is determined from these data, with the eigenvalues being <jats:inline-formula><jats:alternatives><jats:tex-math>$$\\delta _{11} = (-2315\\pm 1)$$</jats:tex-math><mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:mrow> <mml:msub> <mml:mi>δ</mml:mi> <mml:mn>11</mml:mn> </mml:msub> <mml:mo>=</mml:mo> <mml:mrow> <mml:mo>(</mml:mo> <mml:mo>-</mml:mo> <mml:mn>2315</mml:mn> <mml:mo>±</mml:mo> <mml:mn>1</mml:mn> <mml:mo>)</mml:mo> </mml:mrow> </mml:mrow> </mml:math></jats:alternatives></jats:inline-formula> ppm, <jats:inline-formula><jats:alternatives><jats:tex-math>$$\\delta _{22} = (-2492 \\pm 3)$$</jats:tex-math><mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:mrow> <mml:msub> <mml:mi>δ</mml:mi> <mml:mn>22</mml:mn> </mml:msub> <mml:mo>=</mml:mo> <mml:mrow> <mml:mo>(</mml:mo> <mml:mo>-</mml:mo> <mml:mn>2492</mml:mn> <mml:mo>±</mml:mo> <mml:mn>3</mml:mn> <mml:mo>)</mml:mo> </mml:mrow> </mml:mrow> </mml:math></jats:alternatives></jats:inline-formula> ppm, and <jats:inline-formula><jats:alternatives><jats:tex-math>$$\\delta _{33} = (-3071 \\pm 3)$$</jats:tex-math><mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:mrow> <mml:msub> <mml:mi>δ</mml:mi> <mml:mn>33</mml:mn> </mml:msub> <mml:mo>=</mml:mo> <mml:mrow> <mml:mo>(</mml:mo> <mml:mo>-</mml:mo> <mml:mn>3071</mml:mn> <mml:mo>±</mml:mo> <mml:mn>3</mml:mn> <mml:mo>)</mml:mo> </mml:mrow> </mml:mrow> </mml:math></jats:alternatives></jats:inline-formula> ppm.</jats:p&gt

A Novel Nitridoborate Hydride Sr13[BN2]6H8 Elucidated from X‐ray and Neutron Diffraction Data

Metal hydrides are an uprising compound class bringing up various functional materials. Due to the low X-ray scattering power of hydrogen, neutron diffraction is often crucial to fully disclose the structural characteristics thereof. We herein present the second strontium nitridoborate hydride known so far, Sr13[BN2]6H8, formed in a solid-state reaction of the binary nitrides and strontium hydride at 950 °C. The crystal structure was elucidated based on single-crystal X-ray and neutron powder diffraction in the hexagonal space group P63/m (no. 176), exhibiting a novel three-dimensional network of [BN2]3− units and hydride anions connected by strontium cations. Further analyses with magic angle spinning (MAS) NMR and vibrational spectroscopy corroborate the presence of anionic hydrogen within the structure. Quantum chemical calculations reveal the electronic properties and support the experimental outcome. Sr13[BN2]6H8 expands the emerging family of nitridoborate hydrides, broadening the access to an open field of new, intriguing materials

Combining Nitridoborates, Nitrides and Hydrides—Synthesis and Characterization of the Multianionic Sr6N[BN2]2H3

Multianionic metal hydrides, which exhibit a wide variety of physical properties and complex structures, have recently attracted growing interest. Here we present Sr6N[BN2]2H3, prepared in a solid-state ampoule reaction at 800 °C, as the first combination of nitridoborate, nitride and hydride anions within a single compound. The crystal structure was solved from single-crystal X-ray and neutron powder diffraction data in space group P21/c (no. 14), revealing a three-dimensional network of undulated layers of nitridoborate units, strontium atoms and hydride together with nitride anions. Magic angle spinning (MAS) NMR and vibrational spectroscopy in combination with quantum chemical calculations further confirm the structure model. Electrochemical measurements suggest the existence of hydride ion conductivity, allowing the hydrides to migrate along the layers

Green‐Emitting Oxonitridoberyllosilicate Ba[BeSiON2]:Eu2+ for Wide Gamut Displays

Light-emitting diodes (LEDs) producing pure, highly saturated colors are the industry standard for efficient backlighting of high-color gamut displays. Vivid color reproduction, matching the eye's perception of nature, is the central paradigm in the design of narrow-band emitting phosphors. To cover a wide range of naturally occurring color tones, expansion of the color gamut in the green spectral region, and therefore an advanced applicable green phosphor, is highly desired. Herein, the oxonitridoberyllosilicate Ba[BeSiON2]:Eu2+ showing outstanding narrow-band green emission (λmax ≈526 nm with FWHM ≈1600 cm−1 (≈45 nm), x = 0.212, y = 0.715) when excited with InGaN-based blue LEDs is presented. High quantum efficiency and low thermal quenching (>90% rel. quantum efficiency at 100 °C) as well as excellent scalability make the material suitable for industrial application in high color-gamut LED displays. A prototype phosphor-converted-LED (pc-LED), with green-emitting Ba[BeSiON2]:Eu2+ and K2SiF6:Mn4+ as red phosphor shows an extraordinary coverage in the CIE 1931 color space of 109% compared to the DCI-P3 standard, topping the widely applied β-SiAlON:Eu2+ phosphor (104%), making it suitable for use in phone displays, monitors, and television screens

Correlation of the Isotropic NMR Chemical Shift with Oxygen Coordination Distances in Periodic Solids

In Nuclear Magnetic Resonance (NMR) spectroscopy, the isotropic chemical shift δiso is a measure of the electron density around the observed nuclide. For characterization of solid materials and compounds, it is desirable to find correlations between δiso and structural parameters such as coordination numbers and distances to neighboring atoms. Correlations of good quality are easier to find when the coordination sphere is formed by only one element, as the electron density is obviously strongly dependent on the atomic number. The current study is therefore restricted to nuclides in pure oxygen coordination. It is shown that the isotropic shift δiso correlates well with the average oxygen distances (as defined by the coordination sphere) for the nuclides 23Na (with spin I=3/2), 27Al (I=5/2), and 43Ca (I=7/2), using literature data for a range of periodic solids. It has been previously suggested for 207Pb (I=1/2) that δiso may alternatively be related to the shortest oxygen distance in the structure, and our study corroborates this also for the nuclides considered here. While the correlation with the minimal distance is not always better, it has the advantage of being uniquely defined. In contrast, the average distance is strongly dependent on the designation of the oxygen coordination sphere, which may be contentious in some crystal structures

Correlation of the Isotropic NMR Chemical Shift with Oxygen Coordination Distances in Periodic Solids

In Nuclear Magnetic Resonance (NMR) spectroscopy, the isotropic chemical shift δiso is a measure of the electron density around the observed nuclide. For characterization of solid materials and compounds, it is desirable to find correlations between δiso and structural parameters such as coordination numbers and distances to neighboring atoms. Correlations of good quality are easier to find when the coordination sphere is formed by only one element, as the electron density is obviously strongly dependent on the atomic number. The current study is therefore restricted to nuclides in pure oxygen coordination. It is shown that the isotropic shift δiso correlates well with the average oxygen distances (as defined by the coordination sphere) for the nuclides 23Na (with spin I=3/2), 27Al (I=5/2), and 43Ca (I=7/2), using literature data for a range of periodic solids. It has been previously suggested for 207Pb (I=1/2) that δiso may alternatively be related to the shortest oxygen distance in the structure, and our study corroborates this also for the nuclides considered here. While the correlation with the minimal distance is not always better, it has the advantage of being uniquely defined. In contrast, the average distance is strongly dependent on the designation of the oxygen coordination sphere, which may be contentious in some crystal structures

Determination of the Full 207Pb Chemical Shift Tensor of Anglesite, PbSO4, and Correlation of the Isotropic Shift to Lead–Oxygen Distance in Natural Minerals

The full 207 Pb chemical shift (CS) tensor of lead in the mineral anglesite, PbSO 4 , was determined from orientation-dependent nuclear magnetic resonance (NMR) spectra of a large natural single crystal, using a global fit over two rotation patterns. The resulting tensor is characterised by the reduced anisotropy Δ δ = ( - 327 ± 4 ) ppm, asymmetry η C S = 0 . 529 ± 0 . 002 , and δ i s o = ( - 3615 ± 3 ) ppm, with the isotropic chemical shift δ i s o also verified by magic-angle spinning NMR on a polycrystalline sample. The initially unknown orientation of the mounted single crystal was included in the global data fit as well, thus obtaining it from NMR data only. By use of internal crystal symmetries, the amount of data acquisition and processing for determination of the CS tensor and crystal orientation was reduced. Furthermore, a linear correlation between the 207 Pb isotropic chemical shift and the shortest Pb–O distance in the co-ordination sphere of Pb 2 + solely surrounded by oxygen has been established for a large database of lead-bearing natural minerals

Ba12[BN2]6.67H4: A Disordered Anti‐Skutterudite filled with Nitridoborate Anions

Skutterudites are of high interest in current research due to their diversity of structures comprising empty, partially filled and filled variants, mostly based on metallic compounds. We herein present Ba12[BN2]6.67H4, forming a non-metallic filled anti-skutterudite. It is accessed in a solid-state ampoule reaction from barium subnitride, boron nitride and barium hydride at 750 °C. Single-crystal X-ray and neutron powder diffraction data allowed to elucidate the structure in the cubic space group Imurn:x-wiley:14337851:media:anie202316469:anie202316469-math-0001 (no. 204). The barium and hydride atoms form a three-dimensional network consisting of corner-sharing HBa6 octahedra and Ba12 icosahedra. Slightly bent [BN2]3− units are located in the icosahedra and the voids in-between. 1H and 11B magic angle spinning (MAS) NMR experiments and vibrational spectroscopy further support the structure model. Quantum chemical calculations coincide well with experimental results and provide information about the electronic structure of Ba12[BN2]6.67H4