Structure of Molten Mn74Si26 and Molten Mn33.5Si66.5 by Neutron Diffraction

1997 ◽  
Vol 52 (8-9) ◽  
pp. 645-649
Author(s):  
B. Sedelmeyer ◽  
P. Lamparter ◽  
S. Steeb
Keyword(s):  
Correlation Function ◽  
Neutron Diffraction ◽  
Order Parameter ◽  
Short Range ◽  
Short Range Order ◽  
Pair Correlation ◽  
Range Order Parameter ◽  
Compound Formation ◽  
X Ray ◽  
Coordination Numbers

Abstract Molten Mn74Si26 and molten Mn33.5Si66.5 were investigated by neutron diffraction. The pair correlation function yielded, together with the X-ray results from a former paper, the partial coordination numbers, atomic distances, and the short range order parameter with the result that the atomic distribution in molten Mn33.5Si66.5 is statistical while the structure factor of molten Mn74Si26 , as obtained with neutrons, shows a strong prepeak which means rather strong compound formation.

scholarly journals X-Ray and Neutron Diffraction of Amorphous Nickel-Zirconium-Alloys as Prepared in Different Ways

1991 ◽  
Vol 46 (6) ◽  
pp. 491-498 ◽  
Author(s):  
L. Schultz ◽  
P. Lamparter ◽  
S. Steeb
Keyword(s):  
Neutron Diffraction ◽  
Short Range ◽  
Melt Spinning ◽  
Short Range Order ◽  
Pair Correlation ◽  
Zirconium Alloys ◽  
X Ray ◽  
Coordination Numbers ◽  
Structure Factors ◽  
The One

AbstractThe structure of amorphous NiχZr100-χ-alloys (Χ= 30, 31, 34, 63.7, and 65), which were produced by melt spinning (MS), mechanical alloying (MA), and sputtering (SP) was studied by X-ray- and neutron diffraction yielding structure factors, pair correlation functions, coordination numbers, atomic distances, and Warren-Cowley chemical short range order parameters. The atomic arrangement within the first coordination sphere is independent of the method of preparation while in the second and higher spheres it differs between the MS- and the MA-alloys on the one side and the SP-specimens on the other side. Thus one understands that some physical properties of the different specimens differ

An X-ray and Neutron Scattering Study of the Structure of Zinc Vanadate Glasses

2001 ◽  
Vol 56 (6-7) ◽  
pp. 478-488
Author(s):  
Uwe Hoppe ◽  
Rainer Kranold ◽  
Emil Gattef ◽  
Jörg Neuefeind ◽  
David A. Keen
Keyword(s):  
Neutron Diffraction ◽  
Coordination Number ◽  
Short Range ◽  
Short Range Order ◽  
X Ray ◽  
Coordination Numbers ◽  
Gaussian Functions ◽  
Scattering Study ◽  
Neutron Scattering Study ◽  
Vanadate Glasses

Abstract The short-range order of vitreous V20 5 and of three (Zn0)Jt(V20 5)1_x glasses with x = 0.2, 0.4, and 0.5 is studied by X-ray and neutron diffraction experiments where the change of the contrast allows to resolve the V -0 and Z n -0 correlations. The V -0 and the Z n -0 first-neighbor peaks are approximat­ ed by several Gaussian functions. In case of vitreous V20 5 two obvious V -0 distances exist which are related with V 0 4 and V 0 5 units. With ZnO additions the V -O coordination number decreases from 4.4 in vitreous V20 5 to 4.0 in the metavanadate glass where the strongest decrease of the fraction of V 0 5 units is found for glasses of * < 0.2. Dominantly, the V 0 5 groups are linked with the neighboring units by comers. The Z n-0 coordination numbers of the modified glasses are about five with closest dis­ tances of = 0.200 nm.

Pb()O3-type Perovskites: Part I. Pair-correlation Theory of Order-disorder Phase Transition

1997 ◽  
Vol 12 (8) ◽  
pp. 2117-2126 ◽  
Author(s):  
Hyun M. Jang ◽  
Su-Chan Kim
Keyword(s):  
Long Range ◽  
Order Parameter ◽  
Short Range ◽  
Short Range Order ◽  
Pair Correlation ◽  
Range Order ◽  
Statistical Thermodynamic ◽  
Range Order Parameter ◽  
Long Range Order ◽  
Short Range Order Parameter

The limitation of the long-range order parameter and the necessity of the short-range order parameter for the thermodynamic description of Pb()O3-type perovskites are discussed. Based on the discussion, a statistical thermodynamic model that takes into account the configuration of the neighboring B-site ions (B′ and B″ cations) was developed. A pair-correlation approximation was used in the calculation of the configurational entropy and the long-range coulombic interaction energy between the nearest B-site ions. The theoretical calculations using Pb(Sc1/2Ta1/2)O3 (PST) and Pb(Sc1/2Nb1/2)O3 (PSN) systems indicate that the short-range order parameter persists over a wide range of temperatures examined (0–1800 K) and that there possibly occur consecutive long-range order-disorder transitions in the configuration of B-site cations. The possibility of the existence of short-range ordering above the long-range order-disorder transition temperature was also examined using the annealed PSN specimen as a typical example of Pb()O3-type perovskites.

scholarly journals Structure Factors of Liquid Cu-Pb Alloys by Neutron Diffraction

1980 ◽  
Vol 35 (11) ◽  
pp. 1178-1181 ◽  
Author(s):  
Peter Lamparter ◽  
Siegfried Steeb
Keyword(s):  
Neutron Diffraction ◽  
Order Parameter ◽  
Short Range ◽  
Short Range Order ◽  
Marked Effect ◽  
Pair Correlation ◽  
Nearest Neighbour ◽  
Critical Composition ◽  
Structure Factors ◽  
Angle Scattering

Abstract By means of neutron diffraction the structure factors and pair correlation functions of five Cu-Pb alloys, Cu, and Pb in the liquid state have been determined. The nearest neighbour distances have been obtained. The marked effect of small angle scattering with the melt with critical composition (65 at % Cu) is a proof for microsegregation tendency. By comparison with a segregation model for the structure factor the short range order parameter has been derived for melts with 65 and 35 at % Cu, respectively.

Short Range Structure of Amorphous Ni50Ta50-Alloys by Means of X-Ray- and Neutron-Diffraction

1992 ◽  
Vol 47 (7-8) ◽  
pp. 826-832 ◽  
Author(s):  
H. Uhlig ◽  
L. Rohr ◽  
H.-J. Güntherodt ◽  
P. Fischer ◽  
P. Lamparter ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Short Range ◽  
Short Range Order ◽  
Nearest Neighbor ◽  
Range Order ◽  
Partial Structure ◽  
X Ray ◽  
Coordination Numbers ◽  
Binding Behavior ◽  
Structure Factors

Abstract Amorphous Ni50Ta50-samples with their high crystallization temperature of 985 K were investigated. To evaluate the three partial structure factors of amorphous Ni50Ta50 one X-ray diffraction experiment was performed with Ni50Ta50 and two neutron diffraction experiments with Co10Ni40Ta50 and with Ni50Ta50, respectively. The Bhatia-Thornton partial structure factor SCC(Q) indicates rather strong chemical short range order which also explains the premaximum observed in the Faber-Ziman partial SNiNi(Q)-function. The nearest neighbor distance is 2.82 Å for Ni-Ni, 2.91 Å for Ta-Ta, and is shortest for Ni-Ta, 2.44 Å. The coordination numbers are NNiNi = 4.9, NTaTa = 8.2, and NNiTa = 6.0. We report on the chemical short range order and the possible binding behavior in a-Ni50Ta50 and compare the present results with those reported in the literature on a-Ni40Ti60 as well as on a-Ni55Ta45

Nahordnung in binären Schmelzen und Mischkristallen / Short Range Order in Binary Melts and Binary Solid Solubilities

1977 ◽  
Vol 32 (11) ◽  
pp. 1222-1228 ◽  
Author(s):  
Alfred Boos ◽  
Peter Lamparter ◽  
Siegfried Steeb
Keyword(s):  
Solid Solution ◽  
Order Parameter ◽  
Short Range ◽  
Short Range Order ◽  
Range Order ◽  
Range Order Parameter ◽  
Refined Model ◽  
Binary Solid Solution ◽  
X Ray ◽  
Angle Scattering

AbstractThe X-Ray or neutron-intensity scattered from binary melts can be described in a similar way as that from a binary solid solution, namely as a sum of three contributions. One of these contributions describes the short range order scattering which consists of small angle scattering for segregated melts and which leads to premaxima for melts containing compound-like agglomerates. A method is shown to reveal the short range order parameter for the so-called simple model of the melts. A second method leads to the evaluation of the concentration of the agglomerates existing in com­ pound-forming melts for the so-called refined model of the melts.

Local Structure of the Amorphous Ni25Zr75-Alloy by Using the Isotope-Substitution Neutron Diffraction Method

1991 ◽  
Vol 46 (11) ◽  
pp. 951-954
Author(s):  
W.-M. Kuschke ◽  
P. Lamparter ◽  
S. Steeb
Keyword(s):  
Neutron Diffraction ◽  
Local Structure ◽  
Short Range ◽  
Short Range Order ◽  
Diffraction Method ◽  
Isotopic Substitution ◽  
Isotope Substitution ◽  
Coordination Numbers ◽  
Structure Factors ◽  
Neutron Diffraction Method

AbstractUsing neutron diffraction as well as the method of isotopic substitution the partial Bhatia-Thornton as well as the partial Faber-Ziman structure factors of amorphous Ni25Zr75 were determined. A compound forming tendency was found. The atomic distances, partial coordination numbers, and the chemical short range order parameter are evaluated.

Local Atomic Structures in Amorphous and Quasicrystalline Zr70Ni10Pt20and Zr80Pt20Alloys by the Anomalous X-ray Scattering Method

2000 ◽  
Vol 644 ◽  
Author(s):  
Eiichiro Matsubara ◽  
Takahiro Nakamura ◽  
Masaki Sakurai ◽  
Muneyuki Imafuku ◽  
Shigeo Sato ◽  
...  
Keyword(s):  
Short Range ◽  
Short Range Order ◽  
Nearest Neighbor ◽  
Scattering Method ◽  
X Ray ◽  
Coordination Numbers ◽  
Atomic Structures ◽  
X Ray Scattering ◽  
Icosahedral Clusters ◽  
Ray Scattering

AbstractLocal atomic structures around Zr and Pt in a quasicrystalline Zr80Pt20alloy, and amorphous and quasicrystalline Zr70Ni10Pt20alloys have been determined by the anomalous x-ray scattering (AXS) method. A distinct prepeak observed in an intensity profile of the amorphous Zr70Ni10Pt20alloy indicates existence of strong chemical short-range order (CSRO) clusters in the amorphous phase. Total coordination numbers around Zr and Pt in a nearest neighbor region in both alloys have been evaluated. The values around Pt are almost equal to 12 in the amorphous and quasicrystalline states suggest formation of icosahedral clusters around Pt. Some of crystalline structures formed from the quasicrystalline phases by annealing consist of icosahedral clusters of Zr and Ni atoms, or polyhedral clusters of Zr and Pt atoms similar with icosahedral clusters. The present result appears to support that the phase transformation from the amorphous to the crystal through the quasicrystal is explained by the icosahedral CSRO clusters in the amorphous and quasicrystalline states.

Quasi-Chemical Model for Liquid Li-Cd Alloys

1989 ◽  
Vol 44 (6) ◽  
pp. 529-532
Author(s):  
L. C. Prasad ◽  
R. N. Singh
Keyword(s):  
Order Parameter ◽  
Short Range ◽  
Short Range Order ◽  
Chemical Model ◽  
Liquid Alloys ◽  
Range Order Parameter ◽  
Long Wavelength ◽  
Pairwise Interactions ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing

The quasi-chemical model based on pairwise interactions is used to study the concentration dependent thermodynamic properties of Li-Cd liquid alloys. Special attention is given to the concentration-concentration correlation function in the long wavelength limit [Scc(0)] and the chemical short-range order parameter (CSRO). The activity, free energy of mixing, Scc(0) and CSRO are computed as functions of temperature and concentration.

Structure Investigations on Se1-xTex Melts by Neutron Scattering and X-ray Diffraction

1981 ◽  
Vol 36 (8) ◽  
pp. 880-885 ◽  
Author(s):  
W. Hoyer ◽  
B. Kunsch ◽  
M. Suda ◽  
E. Wieser
Keyword(s):  
Correlation Function ◽  
Neutron Scattering ◽  
Diffraction Data ◽  
Short Range ◽  
Short Range Order ◽  
Range Order ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nearest Neighbours ◽  
Structure Investigations

Abstract Neutron scattering results on Se1-xTex melts (x = 0.3, 0.6, 0.8) obtained at 460 °C are combined with earlier X-ray diffraction data. The behaviour of the number and distance of nearest neighbours is discussed with respect to chemical short-range order and transition from twofold to three-fold coordination. For Se70Te30 the radial concentration correlation function 4πr2 ρcc(r) has been evaluated. It shows clearly the preferred formation of unlike pairs (Se-Te) within the chains.

Sign in / Sign up

Export Citation Format

Share Document