A survey of surface tension,molar volume and density for Sn–Ag–Cu–Bi–Sb quinary alloys as lead-free solders

ABSTRACT

By applying the geometric models and the theoretical equation, the surface tension, the molar volume and the density were studied. The empirical calculations were carried out in temperature range 623?K?≤?T?≤?1123?K. Only few thermophysical properties were estimated for eight quinary alloys: Sn3.55Ag0.5Cu3Bi3Sb, Sn3.48Ag0.5Cu3Bi5Sb, Sn3.48 Ag0.5Cu5Bi3Sb, Sn3.40 Ag0.5Cu5Bi5Sb, Sn3.53Ag1Cu3Bi3Sb, Sn3.46Ag1Cu3Bi5Sb, Sn3.46Ag1Cu5Bi3Sb, Sn3.38Ag1Cu5Bi5Sb. The results show that surface tension and density have a linear appearance for all temperatures. We have also studied the influence of the composition and temperature in the studied alloys. The obtained theoretical results are compared with the experimental ones and with the conventional Pb–Sn welds.     

Excess Molar Volume and Viscosity of Isobutyric Acid + Water Binary Mixtures Near and Far Away from the Critical Temperature

The excess molar volume V^E, shear viscosity deviation Δη and excess Gibbs energy of activation ΔG^∗E of viscous flow have been investigated by using density (ρ) and shear viscosity (η) measurements for isobutyric acid + water (IBA+W) mixtures over the entire range of mole fractions at five different temperatures, both near and close to the critical temperature (2.055K ≤ (T−T_c)≤ 13.055K). The results were also fitted with the Redlich–Kister equation. This system exhibited very large negative values of V^E and very large positive values of Δη due to increased hydrogen bonding interactions and correlation length between unlike molecules in the critical region and to very large differences between the molar volumes of the pure components at low temperatures. The activation parameters ΔH^∗ and ΔS^∗ have been also calculated and show that the critical region has an important effect on the volumetric properties.     

Synthesis, crystal structure and mono-dimensional thallium ion conduction of TlFe0.22Al0.78As2O7

A new solid solution TlFe_0.22Al_0.78As₂O₇ has been synthesized by a solid-state reaction. The structure of the title compound has been determined from a single-crystal X-ray diffraction and refined to final values of the reliability factors: R(F²)=0.030 and wR(F²)=0.081 for 1343 independent reflections with I>2σ(I). It crystallizes in the triclinic space group P-1, with a=6.296(2) Å, b=6.397(2) Å, c=8.242(2) Å, α=96.74(2)°, β=103.78(2)°, γ=102.99(3)°, V=309.0(2) Å³ and Z=2. The structure can be described as a three-dimensional framework containing (Fe/Al)O₆ octahedra connected through As₂O₇ groups. The metallic units and diarsenate groups share oxygen corners to form a three-dimensional framework with interconnected tunnels parallel to the a, b and c directions, where Tl⁺ cations are located. The ionic conductivity measurements are performed on pellets of the polycrystalline powder. At 683 K, The conductivity value is 5.23×10⁻⁶ S cm⁻¹ and the ionic jump activation energy is 0.656 eV. The bond valence analysis reveals that the ionic conductivity is ensured by Tl⁺ along the [001] direction.     

Corrigendum on ‘investigation on molecular interaction studies of binary mixture of Dehpa and Petrofin at 298.15 K’

Expressions of Redlich–Kister (RK) excess function using polynomials on difference of molar composition are used. Calculated values of excess properties from experimental values are well presented in some curves as a function of mole fraction (x₂) of the second pure component of the studied binary liquid mixture. Nevertheless, the authors presented values of adjustable parameters, not for the polynomial of the popular RK equation (i.e. vs. x₂–x₁), but for globally the excess property Y^E as an overall three degree polynomial on (x₂) including implicitly the molar fraction product (x₁·x₂) in their nonlinear regression, which can then induces some readers to probable confusion.     

Chitosan-Based Materials for the Removal of Nickel Ions from Aqueous Solutions

Russian Journal of Physical Chemistry A - Sorption of Ni(II) ions from liquid effluents utilizing chemically modified chitosan; (vanillin, polymer I) and (ortho-vanillin, polymer II) is studied...     

New polymorph of CaHPO<Subscript>4</Subscript> (monetite): synthesis and crystal structure

A novel form of anhydrous dicalcium phosphate CaHPO₄ (monetite) is synthesized hydrothermally and characterized by single crystal X-ray diffraction. It crystallizes in the orthorhombic space group Ccm2₁ with a = 6.242(1) Å, b = 6.994(2) Å, c = 7.003(3) Å, V = 305.73(16) ų and it has four independent unit formulas in the unit cell (Z = 4). A three-dimensional crystal structure can be described by {HPO₄}_n infinite zigzag chains linked by Ca–O bonds. The comparison to the crystal structures of other polymorphs is given.     

The iron potassium diarsenate KFeAs2O7 structural, electric and magnetic behaviors

Crystals of a new potassium iron (III) diarsenate (KFeAs₂O₇) have been grown and characterized by single crystal X-ray diffraction. It crystallizes in the triclinic space group , with a=7.662(1) Å, b=8.402(2) Å, c=10.100(3) Å, α=90.42(3)°, β=89.74(2)°, γ=106.39(2)°, V=623.8(3) Å³ and Z=4. The final agreement factors are R=0.0342, wR=0.0889, S(F²)=1.01; the structural model is validated by bond valence sum (BVS) and charge distribution (CD) methods. The structure consists of corner-sharing FeO₆ octahedra and As₂O₇ diarsenate groups, the three-dimensional framework delimits tunnels running along [0 1 0] direction where the potassium ions reside. The crystal structure of the title compound is different from that of the monoclinic KAlP₂O₇ type but structural relationships exist between the frameworks. Impedance measurements (frequency/temperature ranges: 5-13,000 Hz/526-668 K) show KFeAs₂O₇ an ionic conductor being the conductivity 2.76×10⁻⁷ S cm⁻¹ at 568 K and E_a is 0.47 eV. The BVS model suggests that the most probable potassium conduction pathway is along b-direction. Magnetic measurements reveal the Curie—Weiss type paramagnetic behavior over the range 30-300 K and ferromagnetic below 29.3 K.     

Competition of Viscosity Correlation Equations in Isobutyric Acid + Water Binary Mixtures Near and Far Away from the Critical Temperature

Shear viscosity deviations Δη have been investigated by using density (ρ) and kinematic viscosity (ν) measurements for isobutyric acid + water (IBA + W) mixtures over the entire range of mole fractions at atmospheric pressure and at two temperatures (301.15 and 315.15 K). This study extends the temperature range from the five other temperatures investigated in a previous work, 1.055 K≤(T−T _c )≤14.055 K, both far from and close to the critical temperature. This system exhibits very large positive values of Δη due to increased hydrogen bonding interactions and the correlation length between unlike molecules in the critical region, and to very large differences between the molar volumes of the pure components at low temperatures. The results were also fitted with the Redlich–Kister polynomial equations and the recently proposed Herráez correlation equation. Comparisons between the two models at different temperatures and number of parameters are discussed. We note that, in this system where the shear viscosity η as a function of mole fraction (x ₁) of IBA presents a maximum, experimental data are in agreement with the two correlation models when more than three parameters are employed, especially for temperatures far from the critical temperature.     

Synthesis of Human Cancer Associated Globo-H (MBr1) Glycosylamino Acid: Some Mechanistic and Conformational Reinvestigations

The synthesis of an extended globo-H (MBr1 antigen) in the form of a glycosylamino acid is reported. By careful NMR analysis, we found an interesting conformational "flip" on the E ring of some synthetic intermediates. An explanation offered for the successful [3+3] coupling of ABC acceptor 11 and DEF donor 10 possessing a C4 free hydroxyl to produce β-galactoside in azaglycosidations is reinforced.     

Investigations of the reduced Redlich–Kister excess properties of 1,4-dioxane + isobutyric acid binary mixtures at temperatures from 295.15 to 313.15 K

Excess molar volumes and refractive index, molar refraction deviations and isentropic compressibility changes in 1,4-dioxane + isobutyric acid binary mixtures (from 295.15 to 313.15) K. were calculated from experimental density, refractive index and sound velocity data presented in previous work. Here, these experimental values were used to test the applicability of the correlative reduced Redlich–Kister equation as well as their corresponding relative functions which are important to reduce the effect of temperature and, consequently, to reveal the effects of different types of interactions. The results of these observations have been interpreted in terms of structural effects of the solvents. The correlating equation recently proposed by Belda, has also been applied to the present system in order to assess the validity of this equation and to give thermodynamic limiting partial molar quantities interesting to evaluate solute–solvent interaction.