Electronegativity Research Articles

First-principles study on stability of transition metal solutes in aluminum by analyzing the underlying forces

Although there have been some investigations on behaviors of solutes in metals under strain, the underlying mechanism of how strain changes the stability of a solute is still unknown. To gain such knowledge, first-principles calculations are performed on substitution energy of transition metal solutes in fcc Al host under rhombohedral strain (RS). Our results show that under RS, substitution energy decreases linearly with the increase of outermost d radius rd of the solute due to Pauli repulsion. The screened Coulomb interaction increases or decreases the substitution energy of a solute on condition that its Pauling electronegativity scale ϕP is less or greater than that of Al under RS. This paper verifies a linear relation of substitution energy change versus rd and ϕP under RS, which might be instructive for composition design of long life alloys serving in high stress condition.

Effects of Various Mixed Metal Chlorides- AlCl3 in TiCl4/MgCl2/THF Catalytic System on Ethylene Polymerization

In this research, the modification of TiCl4/MgCl2/THF catalyst system with various metal chlorides was investigated on ethylene polymerization. Experimentally, metal chlorides (CaCl2, FeCl2 and ZnCl2) were simultaneously introduced different with TiCl4/MgCl2/THF catalyst. ICP analysis was used to determine the total amount of each metal in the catalyst. For polymerization reaction, TEA was used as cocatalyst and hexane was used as a medium solvent. The Al/Ti molar ratio was 140. The activity result of Ca-Al, Zn-Al and Fe-Al was 979, 1009 and 1476 kgPE/molTi.h, respectively. The coaddition of AlCl3 and FeCl2 in TiCl4/MgCl2/THF catalyst system exhibited the highest activity. It suggested that the co-addition of AlCl3 and FeCl2 has higher electronegativity (EN) and the radius of Fe2+ is closer to Mg2+ resulting in an increased efficiency of the THF removal. This result led to improve the catalyst performance.

Optical and thermal properties of (70 − x)SiO2–xNa2O–15CaO–10Al2O3–5TiO2 (10 ≤ x ≤ 25) glasses

The optical and thermal properties are investigated for the (70 − x)SiO2–xNa2O–15CaO–10Al2O3–5TiO2 (10 ≤ x ≤ 25) glasses using different characterization techniques. Kinetic parameters such as glass transition temperature, activation energy of glass transition (Eg), fluctuation-free volume (fg) and change in bulk thermal expansion coefficient (αf) are calculated for better understanding of glass structure. The Eg shows an increasing trend with the increase of Na2O mol%. Correlation has been established between the microvoids in the glass and physical parameters like density and molar volume. Theoretical parameters like optical basicity, oxide polarizability and electro negativities have been obtained and discussed in relation to non-bridging oxygen. Along with the band gap energy, Urbach energy as well as dispersive energy has also been obtained for all the glasses.

Spectroscopic (FT-IR, FT-Raman and UV) investigation, NLO, NBO, molecular orbital and MESP analysis of 2-{2-[(2,6-dichlorophenyl)amino]phenyl}acetic acid

In this work, FT-IR and FT-Raman spectra of 2-{2-[(2,6-dichlorophenyl)amino]phenyl}acetic acid (abbreviated as 2DCPAPAA) have been reported in the regions 4000–450cm−1 and 4000–50cm−1, respectively. The molecular structure, geometry optimization, intensities, vibrational frequencies were obtained by the ab initio and DFT levels of theory B3LYP with 6-311++G(d,p) standard basis set and a different scaling of the calculated wave numbers. The complete vibrational assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes calculated using vibrational energy distribution analysis (VEDA 4) program. The harmonic frequencies were calculated and the scaled values were compared with experimental FT-IR and FT-Raman data. The observed and the calculated frequencies are found to be in good agreement. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The thermodynamic properties of the title compound at different temperature reveal the correlations between standard heat capacities (C) standard entropies (S) standard enthalpy changes (ΔH). The important non-linear optical properties such as electric dipole momentum, polarizability and first hyperpolarizability of 2DCPAPAA have been computed using B3LYP/6-311++G(d,p) quantum chemical calculations. The Natural charges, HOMO, LUMO, chemical hardness (η), chemical potential (μ), Electro negativity (χ) and electrophilicity values (ω) are calculated and reported.The oscillator’s strength, wave length, and energy calculated by TD-DFT and 2DCPAPAA is approach complement with the experimental findings. The molecular electrostatic potential (MESP) surfaces of the molecule were constructed.

Quantum mechanical calculations and spectroscopic (FT-IR, FT-Raman and UV) investigations, molecular orbital, NLO, NBO, NLMO and MESP analysis of 4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl] benzene-1-sulfonamide

The molecular structural parameters and vibrational frequencies of the fundamental modes of 4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl] benzene-1-sulfonamide(abbreviated as 4MPTFM1HPB1SA) have been obtained using Density functional theory (DFT) technique in the B3LYP approximation with 6-311G(d,p) and 6-311++G(d,p) basis sets. Detailed vibrational assignments of the observed FT-IR and FT-Raman bands have been proposed on the basis of potential energy distribution (PED). The difference between the observed and the calculated wavenumbers values are very small. The theoretically predicted FT-IR and FT-Raman spectra of the title molecule have been constructed. The molecular electrostatic potential has been mapped primarily for predicting sites and relative reactivities toward electrophilic and nucleophilic attack. The intramolecular contacts have been interpreted using Natural Bond Orbital (NBO) and Natural Localized Molecular Orbital (NLMO) analysis. Important non-linear properties such as electric dipolemoment and first hyperpolarizability of 4MPTFM1HPB1SA have been computed using B3LYP quantum chemical calculation. The absorption wavelength, energy and oscillator’s strength are calculated by TD-DFT and 4MPTFM1HPB1SA is approach complement with the experimental findings.The temperature dependence of thermodynamic properties has been analyzed. The Natural charges, Frontier molecular orbitals (FMOs), chemical hardness (η), chemical potential (μ), Electro negativity (χ) and electrophilicity values (ω) are calculated and reported.

Thermal Battery As A Power Sources In Guided Missiles

The battery based on low melting eutectic salt mixture electrolyte is thermally activated by raising the temperature of the electrolyte to its melting point. The battery is capable of discharging at very high rates for short duration. The battery employs a combination of elements with low electronegativity and capable of giving higher electrode potentials such as Ca or Mg as anode, a wide variety of eutectic salt electrolytes and various oxides, sulphates, silicates, phosphates, chromates as cathode depolarizers. Only those thermally activated systems which find application as potential power sources in guided missiles are reviewed.

Rapid Synthesis of Water-soluble NiCl2 Nanorods via Recrystallization for Super Capacitors Applications

Highly uniform NiCl2 nanorods were synthesized successfully via recrystallization and employed as electrode materials for super capacitors applications. The water-soluble Ni/NiCl2 electrode proves to show typical pseudocapacitive characteristics and delivers a very high specific capacitance of 1182.7 F g-1 at 2 A g-1. The charge storage and conversion process initiates from the chemically combination of Ni2+ and OH-, and maintains a reversible redox reaction of Ni(II) ↔ Ni(III) on the electrode. It opens a new insight into the fabrication of multifarious water-soluble inorganic salts for super capacitors applications using the ionic electro negativity parameter as the theoretical guideline.

NMR Spectral Studies of Some Six–membered and Seven–membered Saturated Hetero Cyclic Compounds-calculation of Torsional Angles from Vicinal Coupling Constants–using Altona’s Equation

Some six and seven membered saturated hetero cyclic compounds were prepared; then, from their vicinal coupling constants, proton – proton Torsional angles were calculated using Altona’s Equation. 1 H NMR spectra were recorded in DMSO – d 6 . The chemical shifts were compared with those in CDCl 3 . The COSY, NOESY and 13 C- 1 H correlation spectra had been recorded to assign the signals unambiguously. Then, torsional angles were calculated using electronegativity values of the substituents; the electronegativity value of oxygen was taken to be 3.50.Calculations were made accurately.

Extension and Application of Miedema’s Model in O and S Containing Melts and Alloys

Combined Miedema's model with experimental data provided by Kleppa, the parameters of oxygen and sulfur which were satisfied with Miedema's model were derived: Oxgen: electronegativity 7.04, electronic density 6.03, molar volume 4.59; Sulfur: electronegativity 5.8, electronic density 3.24, and molar volume 6.97. In comparison with results from literature, those parameters had been turned out to be highly reasonable to Miedema's model. The mean absolute percentage error of enthalpies of formation of binary alloying oxides and sulfides were 36.8%, 34.2% respectively. Combining Ding's model, the activities and interaction coefficients between oxygen and other elements of Fe- based alloying melt in 1873 K were derived and further compared with available experimental data. Calculated results were confirmed to be in good agreement with available experimental data, except some special cases. Therefore the long-term problem related with the parameters of oxygen and sulfur for Miedema's model has been resolved successfully by this method. In particular, the special cases Nb, Pt, Ag-their electronegativities(4.05, 5.65, 4.35) were revised to be 4.31, 5.57 and 4.17, respectively, and the revised parameters were much more reasonable than the original parameters.

Quantum Chemical Investigation of the Doppler Broadening of Positron Annihilation Radiation Spectra in Polymers

In order to elucidate the element specificity of the S parameters of polymers containing C, O, or F atoms reported by Sato et al. with the Doppler broadening of positron annihilation radiation measurement [K. Sato, et al., Phys. Rev. B 71, 012201, (2005).], we theoretically analyzed the molecular orbitals of small size of the polymer molecules with an ab initio molecular orbital method. With a linear regression analysis, we found a strong correlation between the average kinetic energies of the valence electrons and the contribution of a free positron to the experimental S parameters for the C-, O-, and F-groups. As with a consideration of the kinetic energies of the valence electrons and the electronegativity of the C, O, and F atoms, we conclude that the element specificity of the experimental S parameters for each of the C-, O-, and F-groups is roughly explained by a difference in the electronegativity of the C, O, and F atoms.

Dependence of the 5D0→7F4 transitions of Eu3+ on the local environment in phosphates and garnets

An overview in details of the luminescence of some materials doped with Eu3+ is given in this paper. The series of samples (garnet structure compounds and phosphates) were synthesized by citric acid or glycolate sol–gel method, and the conventional high temperature solid-state reaction in order to investigate 5D0→7F1, 5D0→7F2, and 5D0→7F4 transitions of Eu3+ ions in these compounds. The optical properties of Eu3+ are discussed with regard to the influence of site symmetry in the compound, electronegativity (EN) and ionic radius of M3+ cations (M=Al, Ga, Y, La, Gd and Lu). In addition, luminous efficacies (LE) and percentage fraction of the 5D0→7F4 transition (integral range of 680–720nm) with respect to the whole Eu3+ emission spectrum (integral range of 570–720nm) are calculated.

Narrow gap electronegative capacitive discharges

Narrow gap electronegative (EN) capacitive discharges are widely used in industry and have unique features not found in conventional discharges. In this paper, plasma parameters are determined over a range of decreasing gap length L from values for which an electropositive (EP) edge exists (2-region case) to smaller L-values for which the EN region connects directly to the sheath (1-region case). Parametric studies are performed at applied voltage Vrf=500 V for pressures of 10, 25, 50, and 100 mTorr, and additionally at 50 mTorr for 1000 and 2000 V. Numerical results are given for a parallel plate oxygen discharge using a planar 1D3v (1 spatial dimension, 3 velocity components) particle-in-cell (PIC) code. New interesting phenomena are found for the case in which an EP edge does not exist. This 1-region case has not previously been investigated in detail, either numerically or analytically. In particular, attachment in the sheaths is important, and the central electron density ne0 is depressed below the d...

Theoretical studies on adsorption of PFOS on anatase TiO2 surfaces

Adsorption behavior of perfluorooctane sulfonate(PFOS) on anatase TiO2 surfaces was studied with DFT-B3LYP method.Physisorption including hydrogen-bond interaction and chemi-adsorption including bidentate binuclear(BB) and monodentate mononuclear(MM) complexes were investigated in the study.Calculations of adsorption energy(Eads) and Gibbs free energy(ΔGads) showed that physisorption was easier to occur.Chemi-adsorption surface complexes were produced by reaction between PFOS and surface water(H2O) or hydroxyl(—OH),and the reaction to replace H2O was easier than that to replace —OH group.MM1(reacted with one H2O of surface) surface complex was the most thermodynamically favorable chemi-adsorption mode.The thermodynamically favorable and stability order of PFOS adsorbed on anatase TiO2 surfaces was H-bonded(hydrogen bonded adsorption)MM1(reacted with one H2O of surface)BB1(reacted with two H2O of surface)MM2(reacted with one —OH of surface)BB2(reacted with one H2O and one —OH of surface).Results of bond length analysis indicated that the interaction between H2O/—OH function group on TiO2 surface and sulfonate group in PFOS resulted in the formation of moderate intensity hydrogen bond.Charges transferred from PFOS molecule to TiO2 surface during chemi-adsorption process,leading to the formation of Ti—O—S bond,and transfered electrons in the process were mainly from strong electronegative atoms O and F.

Effects of Epoxidation and Nitration on Ballistic Properties of FOX‐7 – A DFT Study

Abstract1, 1‐Diamino‐2, 2‐dinitroethylene (FOX‐7) has received increasing attention since it was industrialized in the late 1990s. It has lower sensitivity and comparable performance to RDX. This paper presents ballistic properties of FOX‐7, its mono and dinitro derivatives and their epoxide derivatives computationally. The structures were optimized at the B3LYP/6‐31G(d, p) level and the bond lengths were calculated. The calculated data for FOX‐7 are compatible with the literature one. We have investigated the bond dissociation energies of the molecules. Mulliken electro negativities (χM) and chemical hardness (η) were reviewed using Frontier Molecular Orbitals at HF/6‐31G(d, p)//B3LYP/6‐31G(d, p) theoretical level. The detonation performance analyses were done using empirical Kamlet‐Jacobs equations. Additionally, power index values were calculated. All the compounds considered in the present article are powerful candidates for high energy materials.

Effects of sodium salt of N,N-dimethyldi-thiocarbamate on floatability of chalcopyrite, sphalerite, marmatite and its adsorption properties

Effects of the sodium salt of N,N-dimethyldi-thiocarbamate (DMDC) in the absence and presence of butyl xanthate (BX) on the flotation of chalcopyrite, sphalerite, and marmatite have been investigated. Probable metal complexes and adsorption modes are inferred from UV–vis spectra, Fourier transform infrared (FTIR) and first-principles study. The results show that the presence of iron can reduce the activation of sphalerite, and marmatite can be depressed more readily than sphalerite. It has been found that in the presence of BX, a spot of DMDC can improve the recovery of chalcopyrite (pH 7.5), but is detrimental to the recovery of copper-activated sphalerite/mamatite; in addition, the copper-activated marmatite is depressed more obviously.The results of UV–vis spectra indicate that, DMDC has a stronger capacity of complex with Cu2+ than Zn2+, Fe2+. FTIR analysis shows that when the minerals are pre-treated by DMDC, BX can co-adsorb on the chalcopyrite surface, however, less BX species adsorb on sphalerite and marmatite surfaces. Analyses of group electro negativity calculation show that, compared with BX, the DMDC has stronger effects on the two minerals (chalcopyrite and sphalerite). The adsorption energy calculated also indicates a stronger interaction between DMDC and chalcopyrite (112) (−240.38kJ/mol) than that of sphalerite (110) (−81.65kJ/mol). The adsorption of DMDC on mineral surface occurs through the strong interaction of the S 3p orbital with the 3p, 3d orbital of Cu and 3d orbital of Zn atom. The electrons transfer from the Cu, Zn to S atom, respectively.

From chemistry to mechanics: bulk modulus evolution of Li–Si and Li–Sn alloys via the metallic electronegativity scale

Toward engineering high performance anode alloys for Li-ion batteries, we proposed a useful method to quantitatively estimate the bulk modulus of binary alloys in terms of metallic electronegativity (EN), alloy composition and formula volume. On the basis of our proposed potential viewpoint, EN as a fundamental chemistry concept can be extended to be an important physical parameter to characterize the mechanical performance of Li-Si and Li-Sn alloys as anode materials for Li-ion batteries. The bulk modulus of binary alloys is linearly proportional to the combination of average metallic EN and atomic density of alloys. We calculated the bulk moduli of Li-Si and Li-Sn alloys with different Li concentrations, which can agree well with the reported data. The bulk modulus of Li-Si and Li-Sn alloys decreases with increasing Li concentration, leading to the elastic softening of the alloys, which is essentially caused by the decreased strength of constituent chemical bonds in alloys from the viewpoint of EN. This work provides a deep understanding of mechanical failure of Si and Sn anodes for Li-ion batteries, and permits the prediction of the composition dependent bulk modulus of various lithiated alloys on the basis of chemical formula, metallic EN and cell volume (or alloy density), with no structural details required.

Industrial Application of Reactivity Indices within Density Functional Theory

Reactivity index is that theory which was developed at the right time to rational chemical bonding. Density Functional theory (DFT) has given precision to chemical concepts such as electro negativity, hardness, and softness and has embedded them in a perturbational approach to chemical reactivity. Since the majority of the reactions can be analyzed through the electrophilicity/nucleophilicity of various species involved, a proper understanding of these properties becomes essential. The hard soft acid-base (HSAB) principles classify the interaction between acids and bases in terms of global softness. In last few years the reactivity index methodology is well established and had found its application in a wide variety of systems. This study is to revisit the definition of reactivity index using density functional theory, within the domain of hard soft acid base (HSAB) principle and then to discuss its application in industrial applications; in combination with intra and intermolecular reactivity in materials.

Separation of some heavy metal species from electroplating rinsing solutions by ion exchange resin

A strongly basic anion exchange lewatit MP 600 resin was tested to separate metal species from electroplating rinsing wastewater. An azo resorcinol 4-(2-pyridylazo) dyestuff was used as a complexing agent. Adsorption isotherms were modelled in an ethanol/acetic acid/water media. The loaded resin is regenerated using 4 M HCl whereby the eluted metal species are recovered. Results revealed that mere anion exchangers could not uptake metal ions unless they reacted with the dye to form negatively charged complexes. Trivalent chromium showed significant uptake at pH range of 3.5-4.5. Cadmium, zinc and nickel ions formed complex compounds in the alkaline medium. The electrostatic interaction and formation of complex compounds identified the major adsorption mechanisms. The uptake capacity of the sorbent is directly proportional to the electro negativity of the metal-dye complexes.

Quantum chemical studies on some thiadiazolines as corrosion inhibitors for mild steel in acidic medium

Density functional theory at the B3LYP/6-31G(d,p) basis set level was performed on three thiadiazolines, namely 4-chloro-N-(5-phenyl-1,3,4-thiadiazol-2(3H)-ylidene)aniline (TD01), 4-chloro-N-(5-(4-methoxyphenyl)-1,3,4-thiadiazol-2(3H)-ylidene)aniline (TD02), and 2-(5-(4-chlorophenylimino)-4,5-dihydro-1,3,4-thiadiazol-2-yl) phenol (TD03), and the inhibitive effect of these thiadiazolines against the corrosion of mild steel in acidic medium is elucidated. The calculated quantum chemical parameters correlated to the inhibition efficiency are EHOMO (highest occupied molecular orbital energy), ELUMO (lowest unoccupied molecular orbital energy), the energy gap (ΔE) hardness (η), softness (S), dipole moment (μ), electron affinity (EA) ionization potential (IE), the absolute electro negativity (χ), and the fraction of electron transferred (ΔN). The decreasing order of %IE of the thiadiazolines studied was found to be in agreement with experimental corrosion inhibition efficiencies. The local reactivity has been analyzed through the condensed Fukui function and local softness indices using population analysis.

BAND GAP ENGINEERING OF CRYSTAL MATERIALS: BAND GAP ESTIMATION OF SEMICONDUCTORS VIA ELECTRONEGATIVITY

We have developed empirical equations to quantitatively calculate the band gap values of binary ANB8-N and ternary ABC2 chalcopyrite semiconductors from the general viewpoint of chemical bonding processes upon electronegativity (EN). It is found that the band gap of crystal materials is essentially determined by the binding energy of chemical bonds to the bonding electrons, which can be effectively described by the average attractive abilities of two bonded atoms to their valence electrons and the delocalization degree of the valence electrons. The calculated band gap values of a large number of compounds can agree well with the available experimental data. This work provides us an efficient approach to quantitatively predict the band gap values of inorganic crystal materials on the basis of fundamental atom parameters such as EN, atomic radius, etc.