Thermodynamische Analyse der binären Systeme des Germaniums mit Kupfer, Silber und Gold

1971 ◽  
Vol 26 (4) ◽  
pp. 722-734 ◽  
Author(s):  
B. Predel ◽  
D. W. Stein
Keyword(s):  
Binary Systems ◽  
Enthalpies Of Formation ◽  
Enthalpies Of Solution ◽  
Face Centered Cubic ◽  
Enthalpies Of Mixing ◽  
Electronegativity Difference ◽  
Face Centered ◽  
The Stability ◽  
Electron Compounds ◽  
Liquid Tin

Abstract For the purpose of carrying out a thermodynamic analysis of the binary systems of germanium with copper, silver and gold, the enthalpies of mixing of liquid Cu-Ge and Au-Ge alloys were determined at 1150 °C. Further the enthalpies of mixing of Ag-Ge solid solutions and the enthalpies of formation of the ζ and ε1 phases of the Cu-Ge system were obtained from the enthalpies of solution in liquid tin. It was possible to determine the enthalpy of transformation of germanium from its stable modification into a hypothetical, face-centered cubic structure (ΔHT(Ge) = 13.0 kcal /g-atom) which has a decisive influence on the stability of the solid phases in the systems under consideration. Liquid Cu-Ge alloys show energetic pecularities similar to those existing in the solid state and leading to the formation of electron compounds. A distinct influence of the valency difference of the components can also be demonstrated. In the gold-germanium system, however, the influence of the electronegativity difference of the components is dominant.

scholarly journals Size-Dependent Alloying Ability of Immiscible W-Cu Bimetallic Nanoparticles: A Theoretical and Experimental Study

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1047
Author(s):  
Hongbo Zhang ◽  
Tao Liu ◽  
Siqi Zhao ◽  
Zhanyuan Xu ◽  
Yaozha Lv ◽  
...  
Keyword(s):  
Binary Systems ◽  
Bimetallic Nanoparticles ◽  
Driving Forces ◽  
Phase Particle ◽  
Phase Segregation ◽  
High Yield ◽  
Universal Method ◽  
Face Centered Cubic ◽  
Original Size ◽  
Face Centered

The preparation of alloyed bimetallic nanoparticles (BNPs) between immiscible elements is always a huge challenge due to the lack of thermodynamic driving forces. W–Cu is a typical immiscible binary system, and it is difficult to alloy them under conventional circumstances. Here, we used the bond energy model (BEM) to calculate the effect of size on the alloying ability of W–Cu systems. The prediction results show that reducing the synthesis size (the original size of W and Cu) to less than 10 nm can obtain alloyed W–Cu BNPs. Moreover, we prepared alloyed W50Cu50 BNPs with a face-centered-cubic (FCC) crystalline structure via the nano in situ composite method. Energy-dispersive X-ray spectroscopy (EDS) coupled with scan transmission electron microscopy (STEM) confirmed that W and Cu are well mixed in a single-phase particle, instead of a phase segregation into a core-shell or other heterostructures. The present results suggest that the nanoscale size effect can overcome the immiscibility in immiscible binary systems. In the meantime, this work provided a high-yield and universal method for preparing alloyed BNPs between immiscible elements.

Thermal Stability and Failure Mechanisms of Au/Tiw(N)/Si and Au/TiW(N)/Si02/Si Systems

1996 ◽  
Vol 427 ◽  
Author(s):  
C. R. Chen ◽  
L. J. Chen
Keyword(s):  
Thermal Stability ◽  
Failure Mechanisms ◽  
Cubic Phase ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Single Face ◽  
Face Centered ◽  
The Stability ◽  
Ar Gas

AbstractThermal stability and failure mechanisms of Au/TiW(N)/Si and Au/TiW(N)/SiO2/Si systems have been studied by both conventional and high-resolution transmission electron microscopy, X- ray diffraction and Auger electron spectroscopy. For films deposited in Ar gas containing 20% N2, a single face-centered-cubic phase was the only crystalline phase detected to form. The samples were found to remain stable after annealing at 700 °C for 30 min. The stability temperature for Au/TiW(N)(Ar:N2=80:20)/SiO2/Si samples was found to be higher than those of Au/TiW(N) (Ar:N2=90:10)/SiO2/Si and Au/TiW/SiO2/Si samples.

scholarly journals Simple Metal and Binary Alloy Phases Based on the fcc Structure: Electronic Origin of Distortions, Superlattices and Vacancies

2017 ◽  
Author(s):  
Valentina F. Degtyareva ◽  
Nataliya S. Afonikova
Keyword(s):  
Binary Alloy ◽  
Complex Structures ◽  
Face Centered Cubic ◽  
Energy Contribution ◽  
Simple Metal ◽  
Fermi Sphere ◽  
The Face ◽  
Face Centered ◽  
The Stability ◽  
Fcc Structure

Crystal structures of simple metals and binary alloy phases based on the face-centered cubic (fcc) structure are analyzed within the model of Fermi sphere – Brillouin zone interactions to understand the stability of original cubic structure and derivative structures with distortions, superlattices and vacancies. Examination of the Brillouin-Jones configuration in relation to the nearly-free electron Fermi sphere for several representative phases reveals significance of the electron energy contribution to the phase stability. Representation of complex structures in the reciprocal space clarifies their relationship to the basic cubic cell.

Differential Enthalpies of Solution of Components in Binary Systems 2 CaO . Al2O3 . SiO2-CaO . Al2O3 . 2 SiO2, CaO . SiO2-CaO . Al2O3 . 2 SiO2 and CaO . SiO2-2 CaO . Al2O3 . SiO2

1993 ◽  
Vol 58 (9) ◽  
pp. 1989-1996 ◽  
Author(s):  
Ladislav Kosa ◽  
Ivan Nerád ◽  
Jozef Strečko ◽  
Ivo Proks ◽  
Katarína Adamkovičová
Keyword(s):  
Binary Systems ◽  
The Other ◽  
Enthalpies Of Solution ◽  
Heat Of Solution ◽  
Differential Heat ◽  
Temperature Range ◽  
Enthalpies Of Mixing ◽  
Other Hand ◽  
Temperature Dependences

Differential enthalpies of solution of components in binary systems 2 CaO . Al2O3 . SiO2-CaO . Al2O3 . 2 SiO2, CaO . SiO2-CaO . Al2O3 . 2 SiO2 and CaO . SiO2-2 CaO . Al2O3 . SiO2 as the function of composition and temperature were determined on the base of isothermal composition dependences of enthalpies of mixing and temperature dependences of heats of fusion of their pure components. From the values of the first differential heat of solution of CaO . Al2O3 . 2 SiO2 and 2 CaO . Al2O3 . SiO2 in CaO . SiO2 over temperature range considered we can conclude that the reactions were closed chains of SiO4 tetrahedra in CaO . SiO2 melt break, are exothermic. On the other hand positive values of this quantity for CaO . SiO2 in CaO . Al2O3 . 2 SiO2 and 2 CaO . Al2O3 . SiO2 led us to the conclusion that the progressive breaking originally closed chains in CaO . SiO2 melt has endothermic character.

CHALKOGENIDES OF THE TRANSITION ELEMENTS: II. EXISTENCE OF THE π PHASE IN THE M9S8 SECTION OF THE SYSTEM Fe–Co–Ni–S

1961 ◽  
Vol 39 (2) ◽  
pp. 297-317 ◽  
Author(s):  
Osvald Knop ◽  
Mohammad Anwar Ibrahim
Keyword(s):  
Crystal Structure ◽  
Cobalt Content ◽  
Cubic Phase ◽  
Face Centered Cubic ◽  
Transition Elements ◽  
Maximum Increase ◽  
The Face ◽  
Face Centered ◽  
The Stability ◽  
Stability Limits

The face-centered cubic phase π(Fe,Co,Ni,S) has been shown to exist, at room temperature, within wide composition limits in or close to the M9S8 section of the quaternary system Fe–Co–Ni–S. The M:S ratio of the binary phase π (Co,S) is 9:8 with very narrow homogeneity ranges on both sides of Co9S8, but in π (Fe,Co,Ni,S) the ratio is somewhat higher and appears to increase with decreasing cobalt content. Stoichiometric Co9S8 probably contains a small number of vacancies in both sublattices. It is quite lilcely that the sulphur sublattice is nearly fully occupied and that departures from stoichiometry are caused by the varying degree of occupancy of the metal sublattice.The crystal structure, which was proposed for Co9S8 and for the mineral pentlandite by Lindqvist etal., has been confirmed for these two substances and for π (Fe,Co,Ni,S) in general by X-ray and neutron powder diffraction. The present evidence does not support the crystal structure suggested for natural pentlandite by Eliseev; Eliseev's model does not, in fact, account for the diffraction data of any of the substances examined in this work.Replacement of cobalt in π (Co,S) by iron or nickel or both results in an expansion of the unit cell, the maximum increase in a(π) amounting to about 3%. Cobalt in π (Co,S) cannot be replaced completely by iron or by nickel in samples prepared by dry synthesis, but if the substitution is simultaneous, the π structure will be preserved over a considerable range of compositions even on total replacement. The stability limits of π (Fe,Ni,S) have been found somewhat wider than those stated by Lundqvist.In π phases with the compositions Co8MS8 the metal atoms can conceivably be present in ordered sublattices. This possibility was explored by neutron diffraction in slowly cooled Co8NiS8. Unlike in spinels, where nickel shows a strong preference for octahedral co-ordination, the cobalt and nickel atoms were found to be distributed at random.

The Thermal Stability of a Single-Grain Mg-Zn-Y Icosahedral Quasicrystal

2000 ◽  
Vol 643 ◽  
Author(s):  
Z.P. Luo ◽  
Y.L. Tang ◽  
D.J. Miller ◽  
M.J. Kramer ◽  
I.R. Fisher ◽  
...  
Keyword(s):  
Golden Ratio ◽  
Lattice Parameter ◽  
Icosahedral Quasicrystal ◽  
Face Centered Cubic ◽  
Single Grain ◽  
Face Centered ◽  
The Stability ◽  
Mg Content ◽  
Thermal Stability Of

AbstractThe stability of the Mg-Zn-Y icosahedral quasicrystal (IQC) has been studied by long-term annealing of a single grain IQC in quartz tubes. Decomposition of the IQC was observed after annealing at high temperatures (T≥773 K) sealed in Ar. During the decomposition process, the quasilattice parameter aR was found to decrease, associated with a decrease in Mg content of the IQC phase as confirmed by quantitative x-ray energy dispersive spectroscopy analyses. In addition, a new cubic approximant has been found in the annealed samples. This cubic approximant has a face-centered cubic (fcc) structure with lattice parameter of a = 1.276 nm, which is about (1/τ) times smaller than that of the fcc W'-(MgZnY) with a = 2.05 nm reported previously (where τ is the golden ratio).

scholarly journals Nano Synthesis and Characterization of Complex Derived from Silver Metal Conjugated with Midodrine Hydrochloride

2021 ◽  
Vol 37 (1) ◽  
pp. 157-161
Author(s):  
Namita Bharadwaj ◽  
Jaishri Kaushik
Keyword(s):  
Stability Constant ◽  
Silver Nanoparticle ◽  
Metal Ion ◽  
Ratio Method ◽  
Synthesis And Characterization ◽  
Face Centered Cubic ◽  
Uv Visible ◽  
Face Centered ◽  
The Stability

The stability constant Kf for the complexation of Ag(Ⅰ) metal ion with Midodrine hydrochloride were determinedby spectrophotometric method at room temperature .The colored complexes were measured at 300 nm. The stability constant of the complexes were found to be 5.47 by mole ratio method. The stoichiometry of the complexes formed between the Midodrine drug and Ag (Ⅰ) metal ion are 1:1 M/L ratio. Silver conjugated Midodrine hydrochloride Nano synthesized and characterized by UV/Visible spectroscopy, SEM, XRD and FT-IR. The UV/Visible spectra of Midodrine –Ag nanoparticle in the range of 322 nm. XRD conformThe crystallite size of Midodrine - Ag (Ⅰ) nanoparticles are found to be 64.5 nmfrom Debye Scherer formula.Thecrystallinity of nanoparticles is Face centered cubic structure. SEM conform of particle size and surface morphology, FTIR analyzed involvement of -NH2 group in Midodrine is the stabilized of silver nanoparticle. This research is focuses on complexation, Nano synthesis and characterization of Drug-silver nanoparticle for antihypotention therapy.

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