Rate predictions for two photon spectroscopy of highly charged ions through laser induced recombination

Laser nitriding is used for the fast and easy production of nitride coatings on iron and alloys. Here, first results of the laser nitriding process applied to stainless steel are reported. The laser treatment led to the appearance of additional lines in the Mössbauer spectra, which are attributed to γ-Fe(N) produced by the laser nitriding process. The Mössbauer results are discussed in connection with the results obtained from X-ray diffraction and resonant nuclear reaction analysis. Furthermore, the results of isochronical annealing treatments of laser nitrided iron are reported.     

First-principles calculations of the structural,elastic and electronic properties of MNxC1−x (M = Ti,Zr, Hf; 0 ≤ x ≤ 1) carbonitrides at ambient and elevated hydrostatic pressure

The structural, electronic, and elastic properties of three mixed transition metal carbonitrides TiN_xC_1−x, ZrN_xC_1−x, and HfN_xC_1−x (0 ≤ x ≤ 1) with the rock-salt structure were calculated at ambient and elevated up to 50 GPa hydrostatic pressures in the framework of the density functional theory methods. The lattice constants, densities, and bulk moduli of the considered compounds were shown to behave as linear functions of the nitrogen concentration x. The obtained linear dependencies of all these parameters allow for getting their estimates at any value of x in the range from 0 to 1. Gradual enhancement of the ionicity of the chemical bonds with gradual replacement of carbon by nitrogen was demonstrated by calculating the bond orders and electron density difference distributions.     

Charge Carrier Transport Mechanism in Ta2O5, TaON,and Ta3N5 Studied by Applying Polaron Hopping and Bandlike Models

TaON and Ta₃N₅ are considered promising materials for photocatalytic and photoelectrochemical water splitting. In contrast, their counterpart Ta₂O₅ does not exhibit good photocatalytic performance. This may be explained with the different charge carrier transport mechanisms in these materials, which are not well understood yet. Herein, we investigate the charge transport properties in Ta₂O₅, TaON, and Ta₃N₅ by polaron hopping and bandlike models. First, the polaron binding energies were calculated to evaluate whether the small polaron occurs in these materials. Then we performed calculations to localize the excess carriers as small polarons using a hybrid density functional. We find that the small polaron hopping is the charge transfer mechanism in Ta₂O_5, whereas our calculations indicate that this mechanism may not occur in TaON and Ta₃N₅. We also investigated the bandlike model mechanism by calculating the charge carrier mobility of these materials using the effective mass approximation, but the calculated mobility is not consistent with experimental results. This study is a first step towards understanding charge transport in oxynitrides and nitrides and furthermore establishes a simple rule to determine whether a small polaron occurs in a material.     

Formation of Ammonia from an Iron Nitrido Complex

Radical ideas : Reaction of the iron(IV) nitrido complex [PhB(MesIm)₃Fe?N] (see picture, Mes=2,4,6‐Me₃C₆H₂) with TEMPO‐H (1‐hydroxy‐2,2,6,6‐tetramethylpiperidine) results in high yields of ammonia and quantitative formation of [PhB(MesIm)₃Fe(tempo)]. The mechanism likely involves hydrogen‐atom transfer from TEMPO‐H to the nitrido complex. Similar reaction with the triphenylmethyl radical yields [PhB(MesIm)₃Fe?N? CPh₃].

     

Zirconium scandium oxide nitrides: Formation and decomposition followed in situ by XRD and thermal analysis

The dark green powder of Zr₅₀Sc₁₂O₄₃N₅₀ was produced from Zr₅₀Sc₁₂O₁₁₈ under a constant flow of ammonia. Zr₅₀Sc₁₂O₄₃N₅₀ crystallizes cubic with space group and in the C-M₂O₃ structure (bixbyite structure). The reaction path was followed by in situ X-ray diffraction and showed that the substitution of 3O²⁻ by 2N³⁻ generates additional vacancies on the anion sites in the fluorite basis structure. On the way to the bixbyite structure time- and temperature-controlled X-ray diffractograms revealed the known fluorite-related superstructures (i.e. the vacancy distribution) for the compositions M₁₄X₂₆ and M₇X₁₂. The reverse process, i.e. the oxidation of the oxide nitride was followed in DTA/TG experiments exhibiting the different vacancy orderings at 420, 500 and .     

Phosphor(V)-nitrid α-P3N5: Synthese ausgehend von Tetraaminophosphoniumiodid und Kristallstrukturaufklärung mittels Synchrotron-Pulver-Röntgenbeugung

Phosphorus(V) Nitride α-P₃N₅: Synthesis Starting from Tetraaminophosphonium Iodide and Crystal Structure Determination by Synchrotron Powder Diffraction Pure phosphorus(V) nitride α-P₃N₅ was synthesized by thermal condensation of tetraaminophosphonium iodide [P(NH₂)₄]I at 825 °C as a fine crystalline solid. The crystal structure was solved by direct methods and refined by a Rietveld algorithm on the basis of synchrotron powder diffraction data obtained at the ESRF, Grenoble, on beamline BM1 (α-P₃N₅, Cc, a = 812.077(4), b = 583.433(4), c = 916.005(5) pm, β = 115.809(1)°, Z = 4, 699 observed reflections, wR_p = 0.113, R_p = 0.091, R_F = 0.060). With the same topology of the P–N network structure and similar R values the crystal structure may also be described with space group C2/c. In solid α-P₃N₅ there are PN₄ tetrahedra which are connected through common edges and corners. Two out of five nitrogen each are bridging three and the remaining N are bridging two neighbouring P atoms. In a nonoxidizing atmosphere α-P₃N₅ is stable up to 800 °C. Furthermore the compound is insoluble in all common solvents and resistant against hot acids and alkaline solutions.     

Sonochemical synthesis of graphitic carbon nitrides‐wrapped bimetal oxide nanoparticles hybrid materials and their electrocatalytic activity for xanthine electro-oxidation

A novel network-like magnetic nanoparticle was fabricated on a graphitic carbon nitride through a facile sonochemical route at frequency 20 kHz and power 70 W. To enhance the electrocatalytic activity of the modified materials, the graphitic carbon nitrides (g-C₃N₄) was prepared from melamine. Monitoring of xanthine concentration level in biological fluids is more important for clinical diagnosis and medical applications. As modified CuFe₂O₄/g-C₃N₄ nanocomposite exhibits better electrochemical activity towards the oxidation of xanthine with higher anodic current compared to other modified and unmodified electrode for the detection of xanthine with larger linear range (0.03–695 µM) and lower limit of detection (13.2 nM). To compare with these methods, the electrochemical techniques may be an alternative high sensitive method due to their simplicity and rapid detection time. In addition, the practical feasibility of the sensor was inspected with biological samples, reveals the acceptable recovery of the sensor in real samples.