Pawley and Rietveld refinements using electron diffraction from L12-type intermetallic Au3Fe1-x nanocrystals during their in-situ order-disorder transition

Zhiping Luo, Yolanda Vasquez, James F. Bondi, Raymond Edward Schaak

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

During the in-situ order-disorder transition of intermetallic L12-type Au3Fe1-x nanocrystals, structural information has been retrieved from their electron diffraction patterns based on the Pawley refinement that is unrelated to the electron kinematical or dynamical scattering nature as well as the Rietveld refinement using a kinematical approximation. At room temperature, it was found that the nanocrystals contain approximately x=40% vacancies at the Fe site. Based on in-situ heating this phase displayed an irreversible order-disorder transition, with the transition temperature between 553 and 593K. A sudden increase in lattice parameter was detected during the first heating from the ordered phase, while the second heating of the disordered phase showed only a linear relationship with temperature. From the lattice parameter measurement of the disordered phase, the coefficient of thermal expansion was estimated as 1.462×10-5K-1. The long-range order parameter S was determined by the refined site occupancies, as well as the integrated intensities of the superlattice (100) and fundamental (220) reflections using the Pawley and Rietveld refinements during the order-disorder transition. Considering the dynamical scattering effect, Blackman two-beam approximation theory was applied to corrected S, which slightly attenuated after the correction. A comparison of the electron diffraction with X-ray diffraction data was made. It was demonstrated that elemental and structural information could be retrieved through quantitative electron diffraction studies of the nanomaterials. Since the Pawley refinement algorithm does not include the electron scattering event, it is especially useful to refine the electron diffraction data regardless of the sample thickness.

Original languageEnglish (US)
Pages (from-to)1295-1304
Number of pages10
JournalUltramicroscopy
Volume111
Issue number8
DOIs
StatePublished - Jul 1 2011

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Rietveld refinement
Order disorder transitions
Electron diffraction
Nanocrystals
Intermetallics
intermetallics
nanocrystals
electron diffraction
disorders
Heating
Lattice constants
heating
lattice parameters
Scattering
Approximation theory
Electron scattering
approximation
scattering
Nanostructured materials
Diffraction patterns

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Instrumentation

Cite this

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title = "Pawley and Rietveld refinements using electron diffraction from L12-type intermetallic Au3Fe1-x nanocrystals during their in-situ order-disorder transition",
abstract = "During the in-situ order-disorder transition of intermetallic L12-type Au3Fe1-x nanocrystals, structural information has been retrieved from their electron diffraction patterns based on the Pawley refinement that is unrelated to the electron kinematical or dynamical scattering nature as well as the Rietveld refinement using a kinematical approximation. At room temperature, it was found that the nanocrystals contain approximately x=40{\%} vacancies at the Fe site. Based on in-situ heating this phase displayed an irreversible order-disorder transition, with the transition temperature between 553 and 593K. A sudden increase in lattice parameter was detected during the first heating from the ordered phase, while the second heating of the disordered phase showed only a linear relationship with temperature. From the lattice parameter measurement of the disordered phase, the coefficient of thermal expansion was estimated as 1.462×10-5K-1. The long-range order parameter S was determined by the refined site occupancies, as well as the integrated intensities of the superlattice (100) and fundamental (220) reflections using the Pawley and Rietveld refinements during the order-disorder transition. Considering the dynamical scattering effect, Blackman two-beam approximation theory was applied to corrected S, which slightly attenuated after the correction. A comparison of the electron diffraction with X-ray diffraction data was made. It was demonstrated that elemental and structural information could be retrieved through quantitative electron diffraction studies of the nanomaterials. Since the Pawley refinement algorithm does not include the electron scattering event, it is especially useful to refine the electron diffraction data regardless of the sample thickness.",
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Pawley and Rietveld refinements using electron diffraction from L12-type intermetallic Au3Fe1-x nanocrystals during their in-situ order-disorder transition. / Luo, Zhiping; Vasquez, Yolanda; Bondi, James F.; Schaak, Raymond Edward.

In: Ultramicroscopy, Vol. 111, No. 8, 01.07.2011, p. 1295-1304.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Pawley and Rietveld refinements using electron diffraction from L12-type intermetallic Au3Fe1-x nanocrystals during their in-situ order-disorder transition

AU - Luo, Zhiping

AU - Vasquez, Yolanda

AU - Bondi, James F.

AU - Schaak, Raymond Edward

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N2 - During the in-situ order-disorder transition of intermetallic L12-type Au3Fe1-x nanocrystals, structural information has been retrieved from their electron diffraction patterns based on the Pawley refinement that is unrelated to the electron kinematical or dynamical scattering nature as well as the Rietveld refinement using a kinematical approximation. At room temperature, it was found that the nanocrystals contain approximately x=40% vacancies at the Fe site. Based on in-situ heating this phase displayed an irreversible order-disorder transition, with the transition temperature between 553 and 593K. A sudden increase in lattice parameter was detected during the first heating from the ordered phase, while the second heating of the disordered phase showed only a linear relationship with temperature. From the lattice parameter measurement of the disordered phase, the coefficient of thermal expansion was estimated as 1.462×10-5K-1. The long-range order parameter S was determined by the refined site occupancies, as well as the integrated intensities of the superlattice (100) and fundamental (220) reflections using the Pawley and Rietveld refinements during the order-disorder transition. Considering the dynamical scattering effect, Blackman two-beam approximation theory was applied to corrected S, which slightly attenuated after the correction. A comparison of the electron diffraction with X-ray diffraction data was made. It was demonstrated that elemental and structural information could be retrieved through quantitative electron diffraction studies of the nanomaterials. Since the Pawley refinement algorithm does not include the electron scattering event, it is especially useful to refine the electron diffraction data regardless of the sample thickness.

AB - During the in-situ order-disorder transition of intermetallic L12-type Au3Fe1-x nanocrystals, structural information has been retrieved from their electron diffraction patterns based on the Pawley refinement that is unrelated to the electron kinematical or dynamical scattering nature as well as the Rietveld refinement using a kinematical approximation. At room temperature, it was found that the nanocrystals contain approximately x=40% vacancies at the Fe site. Based on in-situ heating this phase displayed an irreversible order-disorder transition, with the transition temperature between 553 and 593K. A sudden increase in lattice parameter was detected during the first heating from the ordered phase, while the second heating of the disordered phase showed only a linear relationship with temperature. From the lattice parameter measurement of the disordered phase, the coefficient of thermal expansion was estimated as 1.462×10-5K-1. The long-range order parameter S was determined by the refined site occupancies, as well as the integrated intensities of the superlattice (100) and fundamental (220) reflections using the Pawley and Rietveld refinements during the order-disorder transition. Considering the dynamical scattering effect, Blackman two-beam approximation theory was applied to corrected S, which slightly attenuated after the correction. A comparison of the electron diffraction with X-ray diffraction data was made. It was demonstrated that elemental and structural information could be retrieved through quantitative electron diffraction studies of the nanomaterials. Since the Pawley refinement algorithm does not include the electron scattering event, it is especially useful to refine the electron diffraction data regardless of the sample thickness.

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