Effect of Zr concentration on the mechanical and thermodynamic properties of NbIr3 intermetallic compounds from theoretical estimations

ABSTRACT

The iridium is an important metal which has excellent resistance to corrosion at high temperature. L1₂ intermetallic compounds i.e. Ir₃Nb and Ir₃Zr, with similar lattice parameters are ideal for working at high temperature. They are fully soluble due to their low lattice misfit. A first-principle investigation into the effect of doping Zr with different concentrations on the electronic structure, mechanical and thermodynamic properties of NbIr₃ has been studied to prompt the development of novel high-temperature materials. Nine Zr_xNb_8?xIr₂₄ compounds are carefully considered. The results show that adding Zr into these compounds can strengthen their structural stability and ductility. Nevertheless, it reduces the elastic modulus and elastic stiffness. Simultaneously, with the increase of Zr content, the thermodynamic properties of these compounds decrease. It is also found that the changes of elastic modulus are mainly attributed to the variations of bonds in these compounds.     

C-H Activation by dinuclear phosphine bridged complexes of rhodium,iridium, and ruthenium

The possibility of activation of the C-H bond by dinuclear phosphine bridged complexes of rhodium, iridium, and ruthenium is considered.This work was reported at the conference Modern Problems of Organometallic Chemistry (8–13 May, 1994, Moscow).Institut fer Technische Chemie und Petrolchemie der RWTH Aachen Worringerweg 1, 52074 Aachen, Deutschland.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 589–593, April, 1994.     

Decomposition of no on Pd and Ir. Comparison with Pt and Rh

The unimolecular decomposition of NO has been examine on Pd and Ir and they are compared with the corresponding reactions on Pt and Rh. The runs were carried out in a differential flow reactor, at pressures from 0.01 to 5 Torr and temperatures from 500 to 1800 K. It was found that all rates of product formation could be described by Langmuir-Hinshelwood unimolecular rate expression, with an accuracy of±20% und all conditions. The decomposition of NO was virtually identical on Pt and Pd, and on Rh and Ir, but varied widely with temperature between these two groups of metals.     

Coordination compounds of hydrazine derivatives with transition metals,XXIII cobalt(II) chelates of bis(N-salicylidene)dicarboxylic acid dihydrazides

The reaction of bis(N-salicylidene)dicarboxylic acid dihydrazides (H₄ Lig) with cobalt(II) salts was investigated. Chelates of the types Co(H₃ Lig)X ·nH₂O, Co₂(H₂ Lig)X ₂, Co₃(H₃ Lig)₂ X ₄, Co(H₂ Lig) ·nH₂O and Co(H₃ Lig)₂ ·nH₂O (X=Cl, Br, I or SCN) were isolated and characterized by their infrared and electronic spectra as well as their magnetic properties.

---

Koordinationsverbindungen von Hydrazinderivaten mit Übergangsmetallen, 23. Mitt.: Kobalt(II)-Chelate von Bis(N-salicyliden)dicarbonsäuredihydraziden

Zusammenfassung Die Reaktion von Bis(N-salicyliden)dicarbonsäuredihydraziden (H₄ Lig) mit Kobalt(II)-Salzen ergab Chelate vom Typ Co(H₃ Lig)X ·nH₂O, Co₂(H₂ Lig)X ₂, Co₃(H₃ Lig)₂ X ₄, Co(H₂ Lig) ·nH₂O and Co(H₃ Lig)₂ ·nH₂O (X=Cl, Br, I oder SCN). Die Charakterisierung erfolgte mittels IR, Elektronenspektren und magnetischer Eigenschaften.

     

阳离子选择性膜修饰Ir/IrOx-pH电极增敏作用研究

采用阳离子选择性透过膜对Ir/IrOx-pH电极表面进行修饰,提高了电极抗阴离子氧化/还原性物质的干扰能力.利用SEM观察离子选择性透过膜的表面孔径分布;通过循环伏安法研究了氧化物电极在Fe(CN)63- 溶液中的电化学行为.实验表明,选择性透过膜对电极的E-pH线性、准确度、响应时间等无影响,显著改善了电极在含氧化/还原性物质中的使用性能.从而提高了电极的抗干扰能力和灵敏度.     

Novel orange-red light-emitting polymers with cyclometaled iridium complex grafted in alkyl chain

Novel poly(fluorene-alt-carbazole) (PFCz) based copolymers with 3,6-carbazole-N-alkyl grafted iridium complex using 2,3-diphenylpyrazine as ligand (IrBpz) were synthesized by Suzuki polycondensation. The emission of host polymer, PFCz, was completely quenched when the copolymer with 1 mol% of iridium complex. An orange-red emission with CIE coordinate of (0.56, 0.42) was observed from Phosphorescent polymer light-emitting diodes (PhPLEDs). The PhPLEDs made by this copolymer-iridium complex showed a maximum luminous efficiency (LE) of 5.58 cd/A and a maximal luminance of 8625 cd/m². White light with CIE coordinate of (0.33, 0.27) was observed from white PhPLEDs (WPhPLEDs) made by the copolymer containing 0.4 mol% iridium complex. A LE of 2.30 cd/A with luminance of 2068 cd/m² was observed from WPhPLEDs.     

Encapsulation and Enhanced Luminescence Properties of IrIII Complexes within a Hexameric Self‐Assembled Capsule

Encapsulation and luminescence studies of [Ir(ppy)₂(bpy)]Cl (ppy=2‐phenylpyridinate, bpy=2,2′‐bipyridine) within a hexameric resorcinarene capsule are reported. One Ir^III complex cation was encapsulated within the capsule, as demonstrated by NMR and dynamic light scattering (DLS) studies. The emission color of the Ir^III complex was drastically changed from orange to yellow by encapsulation, in contrast with the lack of significant changes in the absorption spectrum. The hexameric capsule effectively hampers the non‐radiative pathway to increase both the luminescence quantum yield and the exited state lifetime. The luminescent properties of the encapsulated Ir^III complex depend on the ratio of Ir^III complex to the resorcinarene monomer as well as the concentration of resorcinarene monomer owing to the reversible process of self‐assembly of the hexameric capsule. Quenching experiments revealed that the Ir^III complex in the capsule was effectively separated from quenchers.     

Electroabsorption study of metal-to-ligand charge transfer in an organic complex of iridium (III)

The dipole moment and polarizability changes have been determined from electroabsorption (EA) spectroscopy of solid films of fac tris(2-(phenyl)pyridinato,N,C^2′)iridium (III) [Ir(ppy)₃]. The maximum changes in the dipole moment |Δμ|_S=(5.0±0.5) D/f (f is the local field correction factor: 1.3–1.7) accompany ground state to the lowest singlet, and |Δμ|_T=(1.7±0.5) D/f ground state to the lowest triplet metal-to-ligand charge transfer (MLCT) excited states formation, while the average polarizability change ų/f² follows from the fitting procedure throughout the visible absorption spectrum range. The experimental values of |Δμ| as well as energy positions of the MLCT states correlate with the literature results of time-dependent density functional theory.