Papers by Keyword: Electronegativity

Abstract: An empirical relation that correlates the optical dielectric constant and the electronegativity difference in A^NB^8-N type binary compounds is presented. The relation uses only one numerical constant common to all I-VII, II-VI and III-V compounds. The simplicity of the relation provides a clue to understand the role of the charge transfer from one atom to another in the origin of the optical dielectric constant. It is also shown that the optical dielectric constant correlates better with the Pauling ionicity scale than with the Phillips ionicity scale. The possible physical background of the found relation is discussed based on the results obtained.

Abstract: The reduction of the M^III/M^II metal couple of complexes Cr (β-diketonato)₃, Fe (β-diketonato)₃ and Mn (β-diketonato)₃ is reviewed and compared. The ease of reduction of the M^III/M^II couple of M(β-diketonato)₃ complexes increases according to the metal sequence Cr (β-diketonato)₃ < Fe (β-diketonato)₃ < Mn (β-diketonato)₃ (with the most positive reduction potential). Good linear relationships obtained between the reduction potential and different electronic parameters related to the β-diketonato ligand on these M^III(β-diketonato)₃ complexes, show that the ease of reduction of the M^III/M^II couple increases with decreasing acidic strength (pK_a) of the respective β-diketone ligands. It also increases with increasing total group electronegativity of the R and R' groups on the respective β-diketonato ligand (RCOCHCOR')⁻ of the M(β-diketonato)₃ complexes, (χ_R + χ_R'), as well as with an increase in the total Hammett sigma meta constants (σ_R + σ_R'), and also with increasing value of the Lever ligand electronic parameter (E_L) of ligand (RCOCHCOR')⁻.

Abstract: The phenomenological approach based on analysis the crystal-chemical parameters and their change depending on concentration of the alloying element for definition of concentration intervals of existence of stable phases with ordered structures in the ternary Titanium Nickelide based alloys is described. It was shown that a comparison of the data of change patterns in crystal-chemical parameters phenomenologically predicted and obtained from experimental data, allows to predict some of the conditions of stabilization in the examined phase, the solubility limits of alloying elements and, consequently, its homogeneity region, as well as formation conditions of multiphase systems. The analysis carried out allows us to make a conclusion regarding the issue that is often discussed in the analysis of phase diagrams of binary and multicomponent systems - what is the ratio of the size and electronic contributions to the stability of the phases. It was shown that the contribution of the size factor to the stabilization of B2 and B19(or В19′) phases is predominant and the role of this factor grows with the increase in the amount of the alloying element.

Abstract: Laboratory metal dusting test of several Ni binary alloys containing the representative element was conducted in a simulated syngas atmosphere at 650°C for 100h. The Ni alloys containing element belonging to Group 14 and 15 in the periodic series exhibited excellent metal dusting resistance, while those containing Group 13 did not. This behavior was able to be reasonably interpreted from the Blyholder mechanism and the concept of Pauling’s electronegativity.

Abstract: In the paper, the factors influencing the band gap bowing of the bulk alloy with random distribution are analyzed and it is found that the bowing coefficient is compositional dependent. The reasons for the large dispersion of the bowing coefficient are also analyzed. In addition, we obtained the bowing coefficient (b=2.26+5.04x) for InAlN by fitting the experimental data.

Abstract: Chalcogenide glasses are suitable for far-infrared and imaging applications. In the present study, Sb10Se90-xGex (x=0, 19, 21, 23, 25, 27) system has been chosen to study structural transformations via physical parameters. Bulk samples with x = 0, 19, 21, 23, 25 and 27 have been prepared using the melt-quenching technique. A theoretical study of the ternary glass system revealed that there was a significant change in the structural environment of the system due to rigidity percolation, which took place as Se was replaced by Ge, and hence resulted in changes in other physical parameters of the system.

Abstract: The relationship between structure, ionic radius and electronegativity and solubility of the various rare-earth elements in Mg was studied. It is found that light RE(La-Sm, Eu, Yb) have more complicated phase relation with Mg but the heavy RE(Gd-Lu, Sc) have the similar crystal structure with magnesium. Also it is found that the less electronegativity difference between Mg and RE is, the more solubility limit of RE in Mg is. The fact of the RE solubility decreased in magnesium with lowering temperature suggests that there is a possibility of Mg supersaturated solid solution formation and it will decomposition during aging. According to the rule, an megnesium alloy with higher strength feature was developed. Their mechanical properties are UTS 347MPa, YTS 290MPa and elongation 12.5% at room temperature.