Manganese Nitride Research Articles

Elaboration on the Electronics of Salen Manganese Nitrides: Investigations into Alkoxy-Substituted Ligand Scaffolds.

The ligand electronics of salen manganese nitride complexes directly influence the locus of oxidation and, thus, the reactivity of the resulting oxidized species. This work investigates the influence of tert-butoxy, isopropoxy, and methoxy substituents on the electronics of salen manganese nitride species and includes the first documentation of the para Hammett value for the tert-butoxy substituent (σpara = -0.13 ± 0.03). Each alkoxy-substituted complex undergoes metal-based oxidation to form manganese(VI), and the kinetics of bimolecular homocoupling to form N2 were assessed by cyclic voltammetry. Bis-oxidation of the manganese complexes was investigated at low temperature using cyclic voltammery and UV-vis-near-IR spectroscopy, and in combination with theoretical calculations, plausible electronic structures of the dications are provided.

Bonding Properties of Manganese Nitrides at High Pressure and the Discovery of MnN4with Planar N4Rings

Bonding Properties of Manganese Nitrides at High Pressure and the Discovery of MnN₄with Planar N₄Rings

Rational design to manganese and oxygen co-doped polymeric carbon nitride for efficient nonradical activation of peroxymonosulfate and the mechanism insight

Polymeric carbon nitride (PCN) based materials have emerged as promising catalysts to activate peroxymonosulfate (PMS) for organic pollutant removal. In this work, the Mn and O co-doped polymeric carbon nitride (Mn/O-PCN) was synthesized via simple calcination and activated PMS for enrofloxacin (ENR) removal. The obtained Mn/O-PCN + PMS system exhibited excellent reactivity for ENR degradation. The Mn and O co-dopants could modulate the electronic structure of PCN. ENR can be oxidized by electrons transferring and 1O2 on the surface of Mn/O-PCN + PMS complex via a non-radical way. A positive correlation was observed between ENR oxidation rates and the Mn content. Effects of pH, PMS concentration, and different ions on the degradation of ENR have also been studied. Cycling experiments showed that Mn/O-PCN materials have good reusability. Our study reported an effective PMS activator for organic pollutants removal and revealed the mechanism of active sites in modified PCN during non-radical PMS activation.

High-thermal-stability resistor formed from manganese nitride compound that exhibits the saturation state of the mean free path

Antiperovskite manganese nitride compounds possess the saturation characteristics of the mean free path at an approximate room temperature. Therefore, such compounds show a flat resistance–temperature curve at an approximate room temperature. In this paper, we propose a manganese nitride resistor for high-thermal-stability systems. We fabricated and evaluated the micro/nanoscale manganese nitride compound resistors using the complementary metal-oxide-semiconductor-compatible process. The thermal coefficient of the fabricated manganese nitride compound resistor was as low as that of other near-zero temperature-coefficient of resistivity materials. These results indicate that manganese nitride compounds can achieve higher thermal stability.

Spin-Orbit-Torque Switching of Noncollinear Antiferromagnetic Antiperovskite Manganese Nitride Mn3GaN

Noncollinear antiferromagnets have promising potential for replacing ferromagnets in the field of spintronics as high-density devices with ultrafast operation. To take full advantage of noncollinear antiferromagnets in spintronics applications, it is important to achieve efficient manipulation of noncollinear antiferromagnetic spin. Here, using the anomalous Hall effect as an electrical signal of the triangular magnetic configuration, spin-orbit-torque switching with no external magnetic field is demonstrated in noncollinear antiferromagnetic antiperovskite manganese nitride ${\mathrm{Mn}}_{3}\mathrm{Ga}\mathrm{N}$ at room temperature. The pulse-width dependence and subsequent relaxation of Hall signal behavior indicate that the spin-orbit torque plays a more important role than the thermal contribution due to pulse injection. In addition, multistate memristive switching with respect to pulse current density is observed. The findings advance the effective control of noncollinear antiferromagnetic spin, facilitating the use of such materials in antiferromagnetic spintronics and neuromorphic computing applications.

Activation of N2 on Manganese Nitride-Supported Ni3 and Fe3 Clusters and Relevance to Ammonia Formation.

Dual-site models were constructed to represent manganese nitride (Mn4N)-supported Ni3 and Fe3 clusters for NH3 synthesis. Density functional theory calculations produced an energy barrier of approximately 0.55 eV for N-N bond activation at the interfacial nitrogen vacancy sites (Nv); also, the hydrogenation and removal of interfacial N is promoted by earth-abundant Ni and Fe metals. Steady-state microkinetic modeling revealed that the turnover frequencies of NH3 production follow an order of Fe3@Mn4N ≈ Ni3@Mn4N > Mn4N > Fe ≫ Ni. Moreover, we present clear evidence that, before NH3 formation, NH migrates from Nv onto the metallic sites. Using N binding energy (BEN) and the transition-state energy of N2 activation (ETS) as descriptors, we concluded that the beneficial effects owing to interfacial Nv sites are the most pronounced when BEN is either too strong or too weak while ETS is high; otherwise, excessive Nv sites may hinder catalyst performance.

Fabrication, mechanical and thermal behaviors of antiperovskite manganese nitride Mn3.1Zn0.5Sn0.4N reinforced aluminum matrix composites

Lightweight aluminum matrix composites with excellent mechanical and thermal properties are urgently required in applications of aerospace, electronics and military industries owning dimensional stability and long-life span. Antiperovskite manganese nitrides can be regarded as ideal reinforcements due to their high mechanical properties, low negative thermal expansion and wide temperature ranges. In this paper, 30 vol % Mn3.1Zn0.5Sn0.4N/Al composites with Mn3.1Zn0.5Sn0.4N particle sizes of 130, 63 and 12 μm were fabricated by vacuum hot-pressing sintering under sintering temperatures of 450, 500 and 550 °C, respectively. Material phase analysis, microstructural characterization, and bulk density measurements of Mn3.1Zn0.5Sn0.4N/Al composites are conducted. Three-point bending and nano-indentation mechanical properties of Mn3.1Zn0.5Sn0.4N/Al composites are studied, while thermal expansion and conductivity of Mn3.1Zn0.5Sn0.4N/Al composites are also investigated. For the Mn3.1Zn0.5Sn0.4N/Al composite sintered at 450 °C with particle size of 130 μm, the Young's modulus of 87.35 GPa, flexural strength of 169.3 ± 7.60 MPa and flexural strain of 3.62 ± 0.09% are produced. Meanwhile, the lowest coefficient of thermal expansion of 3.14 ppm °C−1 and largest thermal conductivity of 126.2 ± 7.0 W m−1 K−1 are possessed as well. Semi-coherent and coherent interfaces of Al–Mn and Sn–Mn3.1Zn0.5Sn0.4N with a width of ~100 nm are determined, which clearly indicates the interfacial characteristics within the Mn3.1Zn0.5Sn0.4N/Al interfacial micro-zones. This work can provide a good understanding and guide for designing and preparing novel structural-functional composite materials with excellent mechanical and thermal properties.

Synthesis and Characterization of the Amidomanganates Rb2[Mn(NH2)4] and Cs2[Mn(NH2)4

We report the successful synthesis of Rb2[Mn(NH2)4] and Cs2[Mn(NH2)4] from ammonothermal conditions at 723 K and pressures above 850 bar. Both compounds were obtained single phase according to powder X-ray diffraction. The crystal structures were determined by single crystal X-ray diffraction. For Rb2[Mn(NH2)4] we have obtained the high-temperature phase. The structures are analyzed with respect to the earlier reported alkali metal amidomanganates. Upon heating in inert atmosphere Cs2[Mn(NH2)4] decomposes to manganese nitrides. IR spectroscopic results are reported.

Fabrication of Metal Matrix Composite Containing Manganese Nitride Showing Giant Negative Thermal Expansion by Compressive Torsion Processing

Fabrication of Metal Matrix Composite Containing Manganese Nitride Showing Giant Negative Thermal Expansion by Compressive Torsion Processing

Giant Magneto-Volume and Magneto-Caloric Effects of Frustrated Antiferromagnet Mn3GaN under Hydrostatic Pressure

Volumetric and caloric effects associated with magnetic transition have been investigated systematically for a series of manganese nitrides based on Mn3GaN. The antiferromagnetic transition tempera...

Direct Pyrolysis of a Manganese-Triazolate Metal-Organic Framework into Air-Stable Manganese Nitride Nanoparticles.

Although metal–organic frameworks (MOFs) are being widely used to derive functional nanomaterials through pyrolysis, the actual mechanisms involved remain unclear. In the limited studies to date, elemental metallic species are found to be the initial products, which limits the variety of MOF‐derived nanomaterials. Here, the pyrolysis of a manganese triazolate MOF is examined carefully in terms of phase transformation, reaction pathways, and morphology evolution in different conditions. Surprisingly, the formation of metal is not detected when manganese triazolate is pyrolyzed in an oxygen‐free environment. Instead, a direct transformation into nanoparticles of manganese nitride, Mn2Nx embedded in N‐doped graphitic carbon took place. The electrically conductive Mn2Nx nanoparticles show much better air stability than bulk samples and exhibit promising electrocatalytic performance for the oxygen reduction reaction. The findings on pyrolysis mechanisms expand the potential of MOF as a precursor to derive more functional nanomaterials.

Combination of theoretical and in situ experimental investigations of the role of lithium dopant in manganese nitride: a two-stage reagent for ammonia synthesis.

Manganese nitride related materials are of interest as two-stage reagents for ammonia synthesis via nitrogen chemical looping. However, unless they are doped with a co-cation, manganese nitrides are thermochemically stable and a high temperature is required to produce ammonia under reducing conditions, thereby hindering their use as nitrogen transfer materials. Nevertheless, when lithium is used as dopant, ammonia generation can be observed at a reaction temperature as low as 300 °C. In order to develop strategies for the improvement of the reactivity of nitride materials in the context of two-stage reagents, it is necessary to understand the intrinsic role of the dopant in the mechanism of ammonia synthesis. To this end, we have investigated the role of lithium in increasing the manganese nitride reactivity by in situ neutron diffraction studies and N2 and H2 isotopic exchange reactions supplemented by DFT calculations.

Multi-layer structures including zigzag sculptured thin films for corrosion protection of AISI 304 stainless steel* *Project supported by the Funds from the University of Mohaghegh Ardabili and University of Tehran and the Iran National Science Foundation (INSF) and the Centre of Excellence for Physics of Structure and Microscopic Properties of Matter, Department of Physics, University of Tehran.

To increase corrosion resistance of the sample, its electrical impedance must be increased. Due to the fact that electrical impedance depends on elements such as electrical resistance, capacitance, and inductance, by increasing the electrical resistance, reducing the capacitance and inductance, electrical impedance and corrosion resistance can be increased. Based on the fact that these elements depend on the type of material and the geometry of the material, multilayer structures with different geometries are proposed. For this purpose, conventional multilayer thin films, multilayer thin film including zigzag structure (zigzag 1) and multilayer thin film including double zigzag structure (zigzag 2) of manganese nitride are considered to protect AISI 304 stainless steel against corrosion in salt solution. These multilayer coatings including zigzag structures are prepared by alternately using the conventional deposition of thin film and glancing angle deposition method. After deposition, the samples are placed in a furnace under nitrogen flux for nitriding. The cross sections of the structures are observed by field emission scanning electron microscopy (FESEM). Atomic force microscope (AFM) is used to make surface analyses of the samples. The results show that the multilayer thin films including zigzag structures have smaller grains than conventional multilayer thin films, and the zigzag 2 structure has the smaller grain than the other two samples, which is attributed to the effect of shadowing and porosity on the oblique angle deposition method. Crystallography structures of the samples are studied by using x-ray diffraction (XRD) pattern and the results show that nitride phase formation in zigzag 2 structure is better than that in zigzag 1 structure and conventional multilayer thin film. To investigate the corrosion resistances of the structures, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests are performed. The results reveal that the multilayer thin films with zigzag structures have better corrosion protection than the conventional multilayer thin films, and the zigzag structure 2 has the smallest corrosion current and the highest corrosion resistance. The electrical impedances of the samples are investigated by simulating equivalent circuits. The high corrosion resistance of zigzag 2 structure as compared with conventional multilayer structure and zigzag 1 structure, is attributed to the high electrical impedance of the structure due to its small capacitance and high electrical resistance. Finally, the surfaces of corroded samples are observed by scanning electron microscope (SEM).

Room temperature anomalous Hall effect in antiferromagnetic Mn3SnN films

Rich magnetic phase transition makes the antiperovskite manganese nitride Mn3AN family an ideal platform to explore the anomalous Hall effect (AHE) with different magnetic configurations. Here, we report the observation of AHE signals up to room temperature in antiferromagnetic (AFM) (001)-oriented Mn3SnN thin films. AHE signals, originated from the Berry curvature, can be controlled by the growth-induced biaxial strain, which leads to the modulation of noncollinear AFM configurations. A relatively large biaxial strain could enhance AHE signals ascribed to the canted AFM structure induced by the piezomagnetic effect. Our findings advance the effective utilization of the AHE in AFM spintronics.

An ultra-incompressible Mn3N compound predicted by first-principles genetic algorithm

Using genetic algorithms for an unbiased structure search and first-principles total-energy calculations, a stable manganese nitride, Mn3N, is discovered. Mn3N is a nonmagnetic metal and isostructural to superhard Re3N. Mn3N exhibits a large bulk modulus and incompressibility comparable to that of the ultra-incompressible OsB. We show that the large bulk modulus can be attributed to the strong covalent bonding in this system. Phonon calculations and analysis confirm the dynamical stability of the Mn3N compound. We also show that weak electron–phonon coupling leads to a small superconducting transition temperature for Mn3N.

Annealing effect on local structure and negative thermal expansion of antiperovskite manganese nitride fine particles

The local structure and thermal expansion properties of balled-milled manganese nitride fine particles with median diameters on the sub-micrometer scale were investigated. Negative thermal expansion (NTE) properties of the manganese nitrides are noticeably altered even with particle sizes of several micrometers. The present study indicates that the alteration of NTE properties is attributable to the structural disorder resulting from grinding. Moreover, the NTE properties were restored by annealing due to improved structural order. These achievements are expected to pave the way for the use of the giant NTE found in manganese nitrides to control thermal expansion in local regions.

Catalytic Hydrogenation of a Manganese(V) Nitride to Ammonia.

The catalytic hydrogenation of a metal nitride to produce free ammonia using a rhodium hydride catalyst that promotes H2 activation and hydrogen-atom transfer is described. The phenylimine-substituted rhodium complex (η5-C5Me5)Rh(MePhI)H (MePhI = N-methyl-1-phenylethan-1-imine) exhibited higher thermal stability compared to the previously reported (η5-C5Me5)Rh(ppy)H (ppy = 2-phenylpyridine). DFT calculations established that the two rhodium complexes have comparable Rh-H bond dissociation free energies of 51.8 kcal mol-1 for (η5-C5Me5)Rh(MePhI)H and 51.1 kcal mol-1 for (η5-C5Me5)Rh(ppy)H. In the presence of 10 mol% of the phenylimine rhodium precatalyst and 4 atm of H2 in THF, the manganese nitride (tBuSalen)Mn≡N underwent hydrogenation to liberate free ammonia with up to 6 total turnovers of NH3 or 18 turnovers of H• transfer. The phenylpyridine analogue proved inactive for ammonia synthesis under identical conditions owing to competing deleterious hydride transfer chemistry. Subsequent studies showed that the use of a non-polar solvent such as benzene suppressed formation of the cationic rhodium product resulting from the hydride transfer and enabled catalytic ammonia synthesis by proton-coupled electron transfer.

Manipulating the Geometric and Electronic Structures of Manganese Nitrides for Ammonia Synthesis

AbstractManganese (Mn) nitrides are important nitrogen (N) carriers for small‐scale intermittent ammonia (NH3) synthesis. However, only 3∼8 % of lattice N are converted into NH3. In this study, the geometric and electronic structures of well‐defined Mn4N and Mn2N lattices were altered using transition metal heteroatoms (Cr, Fe, Co, Ni, Mo) to understand the driving force behind lattice N diffusion and extraction. Density Functional Theory (DFT) revealed that the binding of early hydrogenation product (NH) follows a linear relationship with lattice N over a wide range of close‐packed surfaces. But, the binding of NH2 and NH3 are more sensitive to the geometric and electronic structures. Further, the chemical bonding can be quantitatively characterized with the covalency derived from Crystal Orbital Hamiltonian Population (COHP). In the Eley Rideal‐Mars van Krevelan pathway, the overall NH3 formation free energy ( ) and lattice N diffusion barrier ( ) are the respective thermodynamic and kinetic determining factors. Aided by a rate‐determining step (RDS) model, Mn4N modified with Fe, Co, Ni single‐atom dopants all show enhanced rates for NH3 formation.

Heteroleptic manganese compounds as potential precursors for manganese based thin films and nanomaterials.

Heteroleptic manganese compounds, [Mn(tmhd)(TMEDA)Cl]2 (1), [Mn(tmhd)(dmamp)]2 (2), Mn2(tmhd)2(edpa)2(μ-THF) (3), [Mn(dmampea)(NEt2)]2 (4), and Mn(dmampea)(iPr-MeAMD) (5), were synthesized and characterized. Compound 5 was a volatile liquid. Structural analysis revealed that 1–4 were dimers. Compounds 1 and 3, 2, and 4 had distorted octahedral, distorted trigonal-bipyramidal, and distorted tetrahedral geometries around the Mn centers, respectively. Based on thermogravimetric analysis, the residues of 2 and 3 were expected to be MnO and Mn3O4, respectively. According to thermogravimetric analysis, 4 showed a higher residual value, whereas 5 exhibited a lower value than those expected for manganese nitrides.

Microstructural characterization, mechanical properties and thermal expansion of antiperovskite manganese nitride Mn3.1Zn0.5Sn0.4N fabricated by combing vacuum sintering and spark-plasma sintering

Due to the superior mechanical properties and negative thermal expansion, antiperovskite manganese nitrides have played an important role in many engineering applications, and one of which is that they can be used as ideal reinforced phases to fabricate composites with near-zero thermal expansion. In this study, one type of antiperovskite manganese nitride, Mn3.1Zn0.5Sn0.4N, was initially fabricated by vacuum sintering and subsequently densified by spark-plasma sintering (SPS). The bulk density, material phase and organization analysis are measured after it is densified at different SPS temperatures. Young's modulus, hardness and compressive strength are obtained by using nano-indentation and compression tests, respectively. It is seen that lattice constant, negative thermal expansion and magnetic transition temperature exhibit similar trends, which can be attributed to the lattice distortions caused by changing the SPS temperatures. From this analysis, a systematical study has been conducted to understand the relation between the microstructures, mechanical and thermal properties of antiperovskite manganese nitride.