### Abstract

The best known exception to the Heine-Sampson and Bieber-Gauthier arguments for ordering effects in transition metal alloys (similar to the Hume-Rothery rules) is a NiPt alloy, whose phase diagram is similar to that of the CuAu system. Using neutron scattering we have investigated the local atomic order in a null-matrix Ni0.5262 Pt0.48 single crystal. In a null-matrix alloy, the isotopic composition is adjusted so that the average neutron scattering length vanishes (Ni62 has a negative scattering length nearly equal in magnitude to that of Pt). Consequently, all contributions to the total scattering depending on the average lattice are suppressed. The only remaining components of the elastic scattering are the short-range order (SRO) and size effect terms. These data permit the extraction of the SRO parameters (concentration-concentration correlations) as well as the displacement parameters (concentration-displacement correlations). Using the Krivoglaz-Clapp-Moss theory, we obtain the effective pair interactions (EPIs) between near neighbors in the alloy. The results can be used by theorists to model the alloy in the context of the electronic theory of alloy phase stability, including a preliminary evaluation of the local species-dependent displacements. Our maps of V (q), the Fourier transform of the EPIs, show very similar shapes in the experimental and reconstructed data. This is of importance when comparing to electronic structure calculations.

Original language | English |
---|---|

Article number | 104115 |

Journal | Physical Review B - Condensed Matter and Materials Physics |

Volume | 74 |

Issue number | 10 |

DOIs | |

Publication status | Published - 2006 |

### Fingerprint

### ASJC Scopus subject areas

- Condensed Matter Physics

### Cite this

*Physical Review B - Condensed Matter and Materials Physics*,

*74*(10), [104115]. https://doi.org/10.1103/PhysRevB.74.104115

**Neutron scattering studies of short-range order, atomic displacements, and effective pair interactions in a null-matrix Ni0.5262 Pt0.48 crystal.** / Rodriguez, J. A.; Moss, S. C.; Robertson, J. L.; Copley, J. R D; Neumann, D. A.; Major, J.

Research output: Contribution to journal › Article

*Physical Review B - Condensed Matter and Materials Physics*, vol. 74, no. 10, 104115. https://doi.org/10.1103/PhysRevB.74.104115

}

TY - JOUR

T1 - Neutron scattering studies of short-range order, atomic displacements, and effective pair interactions in a null-matrix Ni0.5262 Pt0.48 crystal

AU - Rodriguez, J. A.

AU - Moss, S. C.

AU - Robertson, J. L.

AU - Copley, J. R D

AU - Neumann, D. A.

AU - Major, J.

PY - 2006

Y1 - 2006

N2 - The best known exception to the Heine-Sampson and Bieber-Gauthier arguments for ordering effects in transition metal alloys (similar to the Hume-Rothery rules) is a NiPt alloy, whose phase diagram is similar to that of the CuAu system. Using neutron scattering we have investigated the local atomic order in a null-matrix Ni0.5262 Pt0.48 single crystal. In a null-matrix alloy, the isotopic composition is adjusted so that the average neutron scattering length vanishes (Ni62 has a negative scattering length nearly equal in magnitude to that of Pt). Consequently, all contributions to the total scattering depending on the average lattice are suppressed. The only remaining components of the elastic scattering are the short-range order (SRO) and size effect terms. These data permit the extraction of the SRO parameters (concentration-concentration correlations) as well as the displacement parameters (concentration-displacement correlations). Using the Krivoglaz-Clapp-Moss theory, we obtain the effective pair interactions (EPIs) between near neighbors in the alloy. The results can be used by theorists to model the alloy in the context of the electronic theory of alloy phase stability, including a preliminary evaluation of the local species-dependent displacements. Our maps of V (q), the Fourier transform of the EPIs, show very similar shapes in the experimental and reconstructed data. This is of importance when comparing to electronic structure calculations.

AB - The best known exception to the Heine-Sampson and Bieber-Gauthier arguments for ordering effects in transition metal alloys (similar to the Hume-Rothery rules) is a NiPt alloy, whose phase diagram is similar to that of the CuAu system. Using neutron scattering we have investigated the local atomic order in a null-matrix Ni0.5262 Pt0.48 single crystal. In a null-matrix alloy, the isotopic composition is adjusted so that the average neutron scattering length vanishes (Ni62 has a negative scattering length nearly equal in magnitude to that of Pt). Consequently, all contributions to the total scattering depending on the average lattice are suppressed. The only remaining components of the elastic scattering are the short-range order (SRO) and size effect terms. These data permit the extraction of the SRO parameters (concentration-concentration correlations) as well as the displacement parameters (concentration-displacement correlations). Using the Krivoglaz-Clapp-Moss theory, we obtain the effective pair interactions (EPIs) between near neighbors in the alloy. The results can be used by theorists to model the alloy in the context of the electronic theory of alloy phase stability, including a preliminary evaluation of the local species-dependent displacements. Our maps of V (q), the Fourier transform of the EPIs, show very similar shapes in the experimental and reconstructed data. This is of importance when comparing to electronic structure calculations.

UR - http://www.scopus.com/inward/record.url?scp=33749262674&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33749262674&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.74.104115

DO - 10.1103/PhysRevB.74.104115

M3 - Article

VL - 74

JO - Physical Review B-Condensed Matter

JF - Physical Review B-Condensed Matter

SN - 0163-1829

IS - 10

M1 - 104115

ER -