Double Nitride Research Articles

Highly Condensed and Super-Incompressible Be2PN3.

Although beryllium and its compounds show outstanding properties, owing to its toxic potential and extreme reaction conditions the chemistry of Be under high-pressure conditions has only been investigated sparsely. Herein, we report on the highly condensed wurtzite-type Be2PN3, which was synthesized from Be3N2 and P3N5 in a high-pressure high-temperature approach at 9 GPa and 1500 °C. It is the missing member in the row of formula type M2PN3 (M=Mg, Zn). The structure was elucidated by powder X-ray diffraction (PXRD), revealing that Be2PN3 is a double nitride, rather than a nitridophosphate. The structural model was further corroborated by 9Be and 31P solid-state nuclear magnetic resonance (NMR) spectroscopy. We present 9Be NMR data for tetrahedral nitride coordination for the first time. Infrared and energy-dispersive X-ray spectroscopy (FTIR and EDX), as well as temperature dependent PXRD complement the analytical characterization. Density functional theory (DFT) calculations reveal super-incompressible behavior and the remarkable hardness of this low-density material. The formation of Be2PN3 through a high-pressure high-temperature approach expands the synthetic access to Be-containing compounds and may open access to various multinary beryllium nitrides.

Highly Condensed and Super‐Incompressible Be2PN3

AbstractAlthough beryllium and its compounds show outstanding properties, owing to its toxic potential and extreme reaction conditions the chemistry of Be under high‐pressure conditions has only been investigated sparsely. Herein, we report on the highly condensed wurtzite‐type Be2PN3, which was synthesized from Be3N2 and P3N5 in a high‐pressure high‐temperature approach at 9 GPa and 1500 °C. It is the missing member in the row of formula type M2PN3 (M = Mg, Zn). The structure was elucidated by powder X‐ray diffraction (PXRD), revealing that Be2PN3 is a double nitride, rather than a nitridophosphate. The structural model was further corroborated by 9Be and 31P solid‐state nuclear magnetic resonance (NMR) spectroscopy. We present 9Be NMR data for tetrahedral nitride coordination for the first time. Infrared and energy‐dispersive X‐ray spectroscopy (FTIR and EDX), as well as temperature dependent PXRD complement the analytical characterization. Density functional theory (DFT) calculations reveal super‐incompressible behavior and the remarkable hardness of this low‐density material. The formation of Be2PN3 through a high‐pressure high‐temperature approach expands the synthetic access to Be‐containing compounds and may open access to various multinary beryllium nitrides.

Engineering of Ti/V bimetallene for selectivity boosting the photocatalytic carbon dioxide hydrogenation reaction

There are still many challenges in inhibiting the recombination and differentiation of photogenerated carriers from promoting the conversion of CO2 into hydrocarbons. Based on the functional differentiation of different metal sites, bimetallic nitride heterostructures is constructed to broaden the optical response and promote the separation of charge carriers in this work. Herein, carbon substrate-loaded double nitride heterostructure composites C@VN/TiN are synthesized by ammonia-assisted one-step calcination. In all samples, the C@VN/TiN-3 sample has the best photoreduction CO2 performance with the promotion of lactic acid (LA) reagent. And the CH4 yield of the C@VN/TiN-3 sample is 775 μmol g−1 h-1, which is 7.6 times and 10.3 times higher than C@VN (102 μmol g−1 h-1) and C@TiN (75 μmolg−1 h-1), respectively. The generation, separation, and migration of photogenerated electron-hole pairs are studied kinetically through transient photocurrent responses, electrochemical impedance spectroscopy and photoluminescence spectroscopy. The position and process of adsorption and activation of CO2 and H2O are deduced by in situ characterization and reaction potential, and the determined possible path is explored by the peak of intermediates. This paper reveals the important roles of co-catalytic agents, ohmic junctions, and the function of bimetallic actives in enhancing photocatalytic activity, providing new ideas for constructing efficient photocatalysts.

Memristive Switching and Density-Functional Theory Calculations in Double Nitride Insulating Layers.

In this paper, we demonstrate a device using a Ni/SiN/BN/p+-Si structure with improved performance in terms of a good ON/OFF ratio, excellent stability, and low power consumption when compared with single-layer Ni/SiN/p+-Si and Ni/BN/p+-Si devices. Its switching mechanism can be explained by trapping and de-trapping via nitride-related vacancies. We also reveal how higher nonlinearity and rectification ratio in a bilayer device is beneficial for enlarging the read margin in a cross-point array structure. In addition, we conduct a theoretical investigation for the interface charge accumulation/depletion in the SiN/BN layers that are responsible for defect creation at the interface and how this accounts for the improved switching characteristics.

Solar Coatings Based on Ag Infrared Reflector with High Stability at Medium and High Temperature

The manufacturing of thermally stable solar coatings with high photo-thermal performance represents a key factor for the further deployment of the CSP technology. Since 2005, ENEA has been developing solar coatings suitable for medium and high temperature applications based on the technology of double nitride cermet, by employing silver and tungsten as infrared reflectors, respectively. Thanks to the high infrared reflectance of silver, the corresponding coatings have better optical performance than those with tungsten; however, the high diffusivity of silver compromises its use at high temperature. In order to improve the structural and chemical stability at medium and high temperature of coatings based on silver, this infrared reflector was placed between compact and uniform layers of metal and cermet manufactured by using high-energy and fast deposition processes. In particular, an Unbalanced Magnetron cathode was adopted to promote an ion-assisted deposition process that improved uniformity and compactness of the metal and cermet films. The new coating shows no photo-thermal parameters degradation after 25 years of service at the operating temperature of 400 °C, while its photo-thermal conversion efficiency decreases by only 1.5% after 25 years of service at an operating temperature of 514 °C.

Boron Phosphorus Nitride at Extremes: PN6 Octahedra in the High-Pressure Polymorph β-BP3 N6.

The high-pressure behavior of non-metal nitrides is of special interest for inorganic and theoretical chemistry as well as materials science, as these compounds feature intriguing elastic properties. The double nitride α-BP3 N6 was investigated by in situ single-crystal X-ray diffraction (XRD) upon cold compression to a maximum pressure of about 42 GPa, and its isothermal bulk modulus at ambient conditions was determined to be 146(6) GPa. At maximum pressure the sample was laser-heated, which resulted in the formation of an unprecedented high-pressure polymorph, β-BP3 N6 . Its structure was elucidated by single-crystal XRD, and can be described as a decoration of a distorted hexagonal close packing of N with B in tetrahedral and P in octahedral voids. Hence, β-BP3 N6 is the first nitride to contain PN6 octahedra, representing the much sought-after proof of principle for sixfold N-coordinated P that has been predicted for numerous high-pressure phases of nitrides.

Boron Phosphorus Nitride at Extremes: PN6 Octahedra in the High‐Pressure Polymorph β‐BP3N6

AbstractThe high‐pressure behavior of non‐metal nitrides is of special interest for inorganic and theoretical chemistry as well as materials science, as these compounds feature intriguing elastic properties. The double nitride α‐BP3N6 was investigated by in situ single‐crystal X‐ray diffraction (XRD) upon cold compression to a maximum pressure of about 42 GPa, and its isothermal bulk modulus at ambient conditions was determined to be 146(6) GPa. At maximum pressure the sample was laser‐heated, which resulted in the formation of an unprecedented high‐pressure polymorph, β‐BP3N6. Its structure was elucidated by single‐crystal XRD, and can be described as a decoration of a distorted hexagonal close packing of N with B in tetrahedral and P in octahedral voids. Hence, β‐BP3N6 is the first nitride to contain PN6 octahedra, representing the much sought‐after proof of principle for sixfold N‐coordinated P that has been predicted for numerous high‐pressure phases of nitrides.

United in Nitride: The Highly Condensed Boron Phosphorus Nitride BP3 N6.

Owing to intriguing materials properties non-metal nitrides are of special interest for both, solid-state chemistry and materials science. Mixed ternary non-metal nitrides, however, have only been sparsely investigated, as preparative chemistry lacks a systematic access, yet. Herein, we report on the highly condensed boron phosphorus nitride BP3 N6 , which was synthesized from (PNCl2 )3 , NH4 N3 and h-BN in a high-pressure high-temperature reaction. By increasing partial pressure of HCl during synthesis using NH4 Cl, single-crystals of BP3 N6 up to 80 μm in length were obtained. The unprecedented framework-type structure determined by single-crystal XRD blends structural motifs of both, α-P3 N5 and c-BN, rendering BP3 N6 a double nitride. The compound was further investigated by Rietveld refinement, EDX, temperature-dependent PXRD, FTIR and solid-state NMR spectroscopy. The formation of BP3 N6 through use of reactive precursors exemplifies an innovative access to mixed non-metal nitrides.

United in Nitride: The Highly Condensed Boron Phosphorus Nitride BP3N6

AbstractOwing to intriguing materials properties non‐metal nitrides are of special interest for both, solid‐state chemistry and materials science. Mixed ternary non‐metal nitrides, however, have only been sparsely investigated, as preparative chemistry lacks a systematic access, yet. Herein, we report on the highly condensed boron phosphorus nitride BP3N6, which was synthesized from (PNCl2)3, NH4N3 and h‐BN in a high‐pressure high‐temperature reaction. By increasing partial pressure of HCl during synthesis using NH4Cl, single‐crystals of BP3N6 up to 80 μm in length were obtained. The unprecedented framework‐type structure determined by single‐crystal XRD blends structural motifs of both, α‐P3N5 and c‐BN, rendering BP3N6 a double nitride. The compound was further investigated by Rietveld refinement, EDX, temperature‐dependent PXRD, FTIR and solid‐state NMR spectroscopy. The formation of BP3N6 through use of reactive precursors exemplifies an innovative access to mixed non‐metal nitrides.

Exotic high-pressure behavior of double nitride CuPN2

On the basis of a combination of the particle-swarm optimization technique and first-principles calculations, we explore the structural and electronic properties of CuPN2 at high pressures up to 160 GPa. The CuPN2 crystallizes in a tI16 structure featuring a three-dimensional tetrahedral network at ambient pressure. Under compression, two structural phase transitions were predicted at 34 and 120 GPa, respectively, with a phase sequence of tI16 → hR4/oC16 → hR4′. The hR4 and oC16 structures are nearly energetically degenerate and both consist of two-dimensional edge-sharing PN6 octahedra network connected by twofold coordinated Cu atoms, whereas the hR4′ structure is built up from edge-sharing PN6 and CuN6 octahedra. All four structures are indirect semiconductors. Unexpectedly, the energy gap collapses by 73% in the first structural transition, and increases abnormally by ∼149% in the second, which is clearly correlated to the evolution trend of the CuN distance, indicating that the CuN bonding environment plays an important role in determining the high-pressure behavior of CuPN2.

Magnesium Double Nitride Mg3GaN3 as New Host Lattice for Eu2+ Doping: Synthesis, Structural Studies, Luminescence, and Band-Gap Determination

The double nitride Mg3GaN3 and binary nitride Mg3N2 were synthesized from the elements by reaction with NaN3 in a sodium flux. Reactions were carried out at 760 °C in welded shut tantalum ampules. Mg3GaN3 was obtained as single crystals (space group R3m (No. 166), a = 3.3939(5) A and c = 25.854(5) A, Z = 3, R1 = 0.0252, wR2 = 0.0616 for 10 refined parameters, 264 diffraction data points). This double nitride consists of an uncharged three-dimensional network of MgN4 and mixed (Mg/Ga)N4 tetrahedra, which share common corners and edges. First-principles density functional theory (DFT) calculations predict Mg3GaN3 to have a direct band gap of 3.0 eV, a value supported by soft X-ray spectroscopy measurements at the N K-edge. Eu2+-doped samples show yellow luminescence when irradiated with UV to blue light (λmax = 578 nm, full width at half maximum (fwhm) = 132 nm). Eu2+-doped samples of Mg3N2 also show luminescence at room temperature when excited with ultraviolet (UV) to blue light. The maximum intensity of...

A Novel Self-Aligned Double-Channel Polysilicon Thin-Film Transistor

In this paper, a high-current self-aligned double-channel polycrystalline silicon thin-film transistor (SA-DCTFT) is proposed, demonstrated, and analyzed. This self-aligned device, which includes two channels, a nitride spacer, two offset-gated structures, and a raised source/drain (RSD) region, reveals better device performance. In addition, the top and bottom channels of the proposed device are self-aligned, and no extra mask is needed as compared with the conventional double-channel devices. Our experimental results show that the on-current of the SA-DCTFT is about twice higher than that of the conventional structure, and the leakage current and kink effect are considerably reduced simultaneously. Moreover, the device stability, such as threshold voltage shift and current degradation under a high gate bias, is enhanced by the proposed self-aligned double channels, nitride spacer, offset-gated structures, and RSD design. The lower drain electric field of the SA-DCTFT is also benefitted to the device scaling down for better performance.

First-principles investigation of structural, electronic and optical properties of IVA group spinel nitrides

The Si3N4 and Ge3N4 are important structural ceramics with many applications because of their attractive high temperature and oxidation resistant properties. The high-pressure and high-temperature spinel phases of these two materials were noticed to have wide, direct electronic band gaps. Other single and double spinel nitrides formed from IVA and IVB group elements have also attracted much attention. Present research focuses on selecting a special substance with promising optical properties and stability besides the attractive electronic properties. The formation energies of spinel nitrides are calculated and stabilities of a group of spinel nitrides are discussed, the structural and electronic properties of them are investigated in detail. By random phase approximation (RPA), the optical properties of spinel nitrides are researched. We obtain that γ-SiGe2N4 has some promising properties with potential technological applications from various aspects. The band transitions which contribute most to the peak of e2 have been identified. An assumption is proposed to raise the peak of e2.

Production of ultrafine iron nitride by double nitriding

Production of ultrafine iron nitride by double nitriding

Theoretical Prediction of the Structure and Properties of Cubic Spinel Nitrides

The structure and properties of cubic spinel nitrides were investigated based on first‐principles theoretical calculations. The lattice constants, bulk moduli, band structures, electronic bonding, and lattice stability of thirty‐nine single and double nitrides were studied. The single spinel nitrides of the form c‐A3N4 (where A is a Group IVA element), except c‐Hf3N4, are all semiconductors with band gaps ranging from an indirect gap of 0.07 eV in c‐Ti3N4 to a direct gap of 3.45 eV in c‐Si3N4. For double nitrides of the form c‐AB2N4 (where A and B are Group IVA (Ti, Zr, Hf) or IVB (C, Si, Ge, Sn) elements), both metallic and insulating band structures are possible. The stability of the double spinel nitrides, relative to single nitrides, is dependent on the optimal cation radii and polyhedral volumes at the tetrahedral A sites and the octahedral B sites. Of the thirty‐two double nitrides, only nine are predicted to be energetically favorable. Among the potentially stable phases, the most interesting ones are c‐CSi2N4 (which has an exceptionally strong covalent bonding and large bulk modulus), c‐SiGe2N4 (which has an energetically favorable direct band gap of 1.85 eV), and c‐SiTi2N4 (which is metallic).

Prediction of spinel structure and properties of single and double nitrides

Lattice constants, bulk moduli, band gaps, electronic bonding, and the stability of 20 new nitrides with spinel structure are studied by first-principles calculations. Double nitrides ${\mathrm{AB}}_{2}{\mathrm{N}}_{4}$ are found to be stable when the counterparts ${\mathrm{BA}}_{2}{\mathrm{N}}_{4}$ are metastable except for ${\mathrm{TiZr}}_{2}{\mathrm{N}}_{4}.$ The four single nitrides ${\mathrm{C}}_{3}{\mathrm{N}}_{4},$ ${\mathrm{Si}}_{3}{\mathrm{N}}_{4},$ ${\mathrm{Ge}}_{3}{\mathrm{N}}_{4},$ and ${\mathrm{Sn}}_{3}{\mathrm{N}}_{4}$ have direct band gaps at the \ensuremath{\Gamma} point ranging from 1.14 to 3.45 eV while ${\mathrm{Zr}}_{3}{\mathrm{N}}_{4}$ and ${\mathrm{Ti}}_{3}{\mathrm{N}}_{4}$ have small indirect gaps. For double nitrides, both metallic and insulating band structures are possible. The total bond orders of the stable double nitrides are larger than those of constituent single nitrides. Among them, ${\mathrm{CSi}}_{2}{\mathrm{N}}_{4}$ shows exceptionally strong covalent bonding and a large bulk modulus. A simple scaling law based on bond lengths can describe the bulk moduli of these spinel nitrides quite well.