Schallgeschwindigkeitsmessung in Bi-Cu Schmelzen zur Bestimmung der Kompressibilität und der partiellen Strukturfaktoren / Sound Velocity, Compressibility, und Partial Structure Factors (q = 0) in Bi-Cu Melts

The adiabatic velocity of ultrasound in molten Bi-Cu alloys was measured at various concentrations and temperatures. For the alloys with concentrations between 40 and 80 a/0 Cu the μ(T)- curves consist of two linear regions with a transition region. Within the concentration range mentioned ⊿u/⊿T and the compressibility show respectively positive and negative deviations from linearity. The deviations can be detected at temperatures up to 1200 C. The total structure factors I(O) for Bi and Cu as well as the partial structure factors aij(O) were obtained. aCuCu(O) shows rather high values, indicating the existence of inhomogeneities containing mainly Cu-atoms. The slope of ⊿Nj' [which is a linear combination of the aij (O)] versus concentration is negative. From this fact follows that segregation must exist in these melts. This also follows from the rather large density fluctuations given by the partial factors SCC(O) obtained in this work.

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Schallgeschwindigkeitsmessung in Al-In-Schmelzen zur Bestimmung der Kompressibilität und der partiellen Strukturfaktoren (s = 0)

Zeitschrift für Naturforschung A ◽

10.1515/zna-1975-6-710 ◽

1975 ◽

Vol 30 (6-7) ◽

pp. 784-788

Author(s):

Jochen Hoehler ◽

Siegfried Steeb

Keyword(s):

Linear Combination ◽

Transition Region ◽

Positive Deviation ◽

Partial Structure ◽

Structure Factors ◽

Velocity Of Ultrasound ◽

Versus Concentration

Abstract The adiabatic velocity of ultrasound u in molten AI, In, and Al-In alloys was measured at various concentrations and temperatures. For the alloys the u(T) curves consist of two linear regions with a transition region. The function ⊿u/⊿T and the compressibility versus concentration show positive deviation from linearity. In the latter case the deviation at 1000 °C is smaller than that at 880 °C. The partial structure factors aij(O) were obtained, aAl,Al(0) and aIn,In(0) showing rather high positive, and aAl,In(0) rather high negative values. Thus the segregation tendency becomes obvious. This also can be deduced from the plot of Nń [which is a linear combination of the aij (0) ] versus concentration.

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Velocity of ultrasound in molten au-co alloys for the determination of compressibility and partial structure factors

Physics and Chemistry of Liquids ◽

10.1080/00319107708084134 ◽

1977 ◽

Vol 6 (2) ◽

pp. 113-125 ◽

Cited By ~ 7

Author(s):

Richard Bek ◽

Siegfried Steeb

Keyword(s):

Partial Structure ◽

Structure Factors ◽

Velocity Of Ultrasound ◽

Co Alloys

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Real space manifestation of the first sharp diffraction peak in the structure factor of liquid and glassy materials

Proceedings of the Royal Society of London. Series A: Mathematical and Physical Sciences ◽

10.1098/rspa.1994.0065 ◽

1994 ◽

Vol 445 (1924) ◽

pp. 351-365 ◽

Cited By ~ 177

Keyword(s):

Structure Factor ◽

Real Space ◽

Density Fluctuations ◽

Diffraction Peak ◽

Minimum Size ◽

Structural Units ◽

Structure Factors ◽

Oscillatory Character ◽

Glassy Materials ◽

Total Structure

The problem of those discernible features of the intermediate range order (IRO) which can be attributed to the first sharp diffraction peak (FSDP) observed in the structure factor of many liquid and glassy materials is approached by treating this peak as a distinct feature. It is found, by considering the measured partial structure factors, S αβ ( k ), for molten ZnCl 2 , GeSe 2 , MgCl 2 , NiBr 2 and Nil 2 and the measured total structure factors, F ( k ), for glassy SiO 2 , PS 4 and liquid CCl 4 , that the propensity of the FSDP to have a prominent effect on the underlying features of the IRO depends noticeably on the system type. Specifically, the FSDP confers a marked oscillatory character of periodicity 2π/ k 1 (where k 1 is the FSDP position) on the IRO when the local structural units, which give rise to the density fluctuations on the IRO scale, exist as stable entities for a timescale τ ≫ 5 × 10 -12 s. The FSDP therefore accounts for the discernible features of the underlying IRO for the viscous glass forming liquids ZnCl 2 and GeSe 2 , for the glasses SiO 2 and PS 4 , and for the molecular liquid CCl 4 . The influence of the FSDP on the IRO is less pronounced for molten MgCl 2 and is negligible for molten NiBr 2 and Nil 2 , both of which have a high cation mobility which leads to a relative instability of the Ni 2+ centred structural units. The effect on the FSDP of temperature and pressure are briefly considered as are the development of the FSDP in molten ZnX 2 (when X is changed from Cl to I to Br) and the minimum size of r -space model which is required if the FSDP is to be accurately predicted.

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X-ray Diffraction Study of Molten Te and Tl-Te Alloys

Zeitschrift für Naturforschung A ◽

10.1515/zna-1975-1223 ◽

1975 ◽

Vol 30 (12) ◽

pp. 1655-1660 ◽

Cited By ~ 36

Author(s):

Y. Waseda ◽

S. Tamaki

Keyword(s):

Structure Factor ◽

Molten Metals ◽

X Ray Diffraction ◽

Partial Structure ◽

X Ray ◽

Partial Structures ◽

Structure Factors ◽

Diffraction Patterns ◽

Total Structure ◽

Constituent Elements

Abstract X-ray diffraction patterns have been obtained from molten Te at 470, 520 and 570 °C. The heights of the peak maxima in the structure factor were much the same in contrast with those of typical molten metals such as sodium.Molten Tl-Te alloys have been studied by X-ray diffraction for the alloy compositions 25, 33.3, 50, 60 and 75 at% Te at 500 °C and at about 20 °C above the liquidus. The total structure factors for the 25 and 33.3 at% Te alloys were almost the same as that of pure Tl. This implies that the atomic arrangement of these molten alloys is very close to that of pure Tl. Although a drastic change is not found in the general form of the structure factor, the parameter of the range of local atomic order abruptly increases on passing from Tl2Te to more Te-rich alloys. The three partial structures were also evaluated from the observed X-ray intensities assuming that each partial structure is independent of the relative abundance of the constituent elements in the alloys.

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Structure of the Molten 37 a/o Cu-63 a/o Sb Alloy Using the Isotopic Substitution Method in Neutron Diffraction

Zeitschrift für Naturforschung A ◽

10.1515/zna-1978-0412 ◽

1978 ◽

Vol 33 (4) ◽

pp. 472-479 ◽

Cited By ~ 3

Author(s):

W. Knoll ◽

S. Steeb

Keyword(s):

Neutron Diffraction ◽

Pair Correlation ◽

Neutron Diffraction Study ◽

Number Density ◽

Partial Structure ◽

Distance Correlation ◽

Structure Factors ◽

Total Structure ◽

The Fourier Transform ◽

Strong Segregation

A neutron diffraction study of the eutectic Cu-Sb-melt containing 37 a/o Cu has been performed using isotopically enriched samples. The three partial structure factors describing the Cu-Cu, Cu-Sb, and Sb-Sb correlations have been determined as well as a second set of partial structure factors relating to the distance correlation of fluctuations in number density and concentration. Unsmoothed total structure factors were used. By Fourier-transformation the corresponding pair correlation functions were obtained. A strong segregation tendency was found. Concentration fluctuations with a correlation length of 2.4 Å could be determined. From the Fourier-transform of SCC the product N̄1α1 was obtained confirming the segregation tendency. The distance of nearest Cu-Cu neighbours in the eutectic Cu-Sb melt was found to be smaller than in pure molten Cu, whereas the Sb-Sb distance is larger than in pure Sb. According to Faber-Ziman theory the electrical resistivity was calculated and compared with experimental data.

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The structure of molten and glassy 2:1 binary systems: an approach using the Bhatia—Thornton formalism

Proceedings of the Royal Society of London. Series A: Mathematical and Physical Sciences ◽

10.1098/rspa.1992.0081 ◽

1992 ◽

Vol 437 (1901) ◽

pp. 591-606 ◽

Cited By ~ 96

Keyword(s):

Structure Factor ◽

Binary Systems ◽

Range Order ◽

Partial Structure ◽

Systematic Analysis ◽

Glass Forming ◽

Structure Factors ◽

Total Structure Factor ◽

Diffraction Patterns ◽

Total Structure

A systematic analysis of those liquid binary 2:1 systems (denoted MX 2 ), for which experimental partial structure factors are available from the isotopic substitution method in neutron diffraction, is made using the Bhatia-Thornton (BT) formalism.Particular attention is paid to the origin of the first sharp diffraction peak (FSDP ), which occurs in the measured diffraction patterns for some of the MX 2 systems, since it appears, from recent studies, that this feature is a signature of directional bonding. It is found that FSDPS can occur in all three BT partial structure factors S xB (k). A FSDP feature in the concentration-concentration partial structure factor S cc (k) is not, however, pronounced except in the case of MgCl 2 and the glass forming network melts ZnCl 2 and GeSe 2 . To the extent that these systems can be regarded as ionic melts a FSDP in S cc (k) implies a non-uniformity in the charge distribution on the scale of the intermediate-range order (IRO). The structure of molten GeSe 2 is compared with the structures of molten ZnCl 2 , glassy GeS 2 and glassy Si0 2 . Although the GeSe 2 and ZnCl 2 melts have different short-range order, there are similarities in the observed IRO which can be attributed to the arrangement of the electropositive species M. The essential features of the measured total structure factor for glassy GeS 2 can be reproduced by using the molten GeSe 2 S zB (k). This result lends support to the notion that the S zB (k) for liquid GeSe 2 (and ZnCl 2 ) are characteristic of both the liquid and glassy states of other network glass forming systems. The structures of molten GeSe 2 (or ZnCl 2 ) and glassy Si0 2 are, however, found to be different. The observed discrepancies are largest in the region of the FSDP which signifies pronounced differences in the nature of the IRO for these systems.

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Evaluation of Partial Structure Factors in the Small Q-Region with Amorphous Ni80P20 by Neutron Diffraction Using Isotopic Substitution

Zeitschrift für Naturforschung A ◽

10.1515/zna-1985-0604 ◽

1985 ◽

Vol 40 (6) ◽

pp. 551-558 ◽

Cited By ~ 14

Author(s):

K. Schild ◽

F. Frisius ◽

P. Lamparter ◽

S. Steeb

Keyword(s):

Elastic Scattering ◽

Neutron Diffraction ◽

Fourier Transforms ◽

Total Content ◽

Density Fluctuations ◽

Isotopic Substitution ◽

Partial Structure ◽

Correlation Lengths ◽

Structure Factors ◽

Melt Spin

Amorphous Ni80P20-alloys were produced under He-atmosphere by the melt spin technique. With three specimens produced from P with natNi, 62Ni and 0Ni elastic scattering expriments were performed using neutrons with l = 5.4 Å in the Q-region 6 · 10−3 Å−1 ≦ Q ≦ 2.7 · 10−1 Å−1 . The measured intensities were corrected for absorption and background, desmeared, and normalized. The partial Bhatia Thornton structure factors SNN, SCC, and SNC w e r e evaluated and allowed the following conclusions: The a-Ni80P20-alloy contains regions with radii of about 6.5 Å caused by concentration fluctuations. A method is presented which allows to determine the composition of the regions and the total content of regions within the specimen. In the small Q-region (6 · 10−3 Å−1 ≦ Q ≦ 4 · 10−2 Å−1) the run of the partial structure factors is proportional to Q−3caused by concentration- and density-fluctuations. From the partial Fourier transforms follows a slight anisotropy concerning the chemical arrangement with correlation lengths elongated along the ribbon direction.

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Structural evidence of complex formation in liquid Pb–Te alloys

High Temperature Materials and Processes ◽

10.1515/htmp-2020-0064 ◽

2020 ◽

Vol 39 (1) ◽

pp. 261-269

Author(s):

Toru Akasofu ◽

Masanobu Kusakabe ◽

Shin’ichi Takeda ◽

Shigeru Tamaki

Keyword(s):

Neutron Diffraction ◽

Structural Data ◽

Reverse Monte Carlo ◽

Partial Structure ◽

Resistivity Measurements ◽

Conduction Electrons ◽

Voronoi Polyhedron ◽

Structure Factors ◽

Spatial Configurations ◽

Total Structure

AbstractThe former analysis of the structural data in liquid Pb–Te alloys, based on the neutron diffraction measurements for this system, was insufficient to obtain the microscopic and spatial configurations in this system. In order to obtain these configurations, we have newly analyzed by using the Reverse Monte Carlo simulations and the method of Voronoi polyhedron. The partial structure factors {S}_{ij}(Q) and thereby {g}_{ij}(r) are newly estimated by using the former data of neutron diffraction measurements, which are now exactly reproduced by the obtained total structure factors S(Q). From these results, it is concluded that the liquid Pb0.5Te0.5 is spatially configured by the mixture of some sorts of covalent-type formation of PbTe molecules and dissociated Pb and/or Te ions with conduction electrons, which result is completely consistent with results of electrical resistivity measurements and also with the thermodynamic analysis.

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