ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • bond-valence methodcoordination numberscrystal radiibond-valence parametersbond softness  (2)
  • Al/Si orderingvacancy orderingceramicssuperspaceincommensurate structures  (1)
  • International Union of Crystallography (IUCr)  (3)
Collection
Keywords
Publisher
  • International Union of Crystallography (IUCr)  (3)
Years
  • 1
    facet.materialart.
    Unknown
    International Union of Crystallography (IUCr)
    In: IUCrJ
    Publication Date: 2017-09-02
    Keywords: bond-valence methodcoordination numberscrystal radiibond-valence parametersbond softness
    Electronic ISSN: 2052-2525
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    facet.materialart.
    Unknown
    International Union of Crystallography (IUCr)
    In: IUCrJ
    Publication Date: 2017-08-04
    Description: Based on a description of bond valence as a function of valence electron density, a systematic bond softness sensitive approach to determine bond-valence parameters and related quantities such as coordination numbers is elaborated and applied to determine bond-valence parameters for 706 cation–anion pairs. While the approach is closely related to the earlier softBV parameter set, the new softNC1 parameters proposed in this work may be simpler to apply in plausibility checks of crystal structures, as they follow the first coordination shell convention. The performance of this softNC1 bond-valence parameter set is compared with that of the previously derived softBV parameter set that also factors in contributions from higher coordination shells, and with a benchmarking parameter set that has been optimized following the conventional choice of a universal value of the bond-valence parameter b. The results show that a systematic adaptation of the bond-valence parameters to the bond softness leads to a significant improvement in the bond-valence parameters, particularly for bonds involving soft anions, and is safer than individual free refinements of both R0 and b from a limited number of reference cation environments.
    Keywords: bond-valence methodcoordination numberscrystal radiibond-valence parametersbond softness
    Electronic ISSN: 2052-2525
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    facet.materialart.
    Unknown
    International Union of Crystallography (IUCr)
    In: IUCrJ
    Publication Date: 2018-06-26
    Description: Synchrotron single-crystal X-ray diffraction has revealed diffuse scattering alongside sharp satellite reflections for different samples of mullite (Al4+2xSi2−2xO10−x). Structural models have been developed in (3+1)-dimensional superspace that account for vacancy ordering and Al/Si ordering based on harmonic modulation functions. A constraint scheme is presented which explains the crystal-chemical relationships between the split sites of the average structure. The modulation amplitudes of the refinements differ significantly by a factor of ∼3, which is explained in terms of different degrees of ordering, i.e. vacancies follow the same ordering principle in all samples but to different extents. A new approach is applied for the first time to determine Al/Si ordering by combining density functional theory with the modulated volumes of the tetrahedra. The presence of Si–Si diclusters indicates that the mineral classification of mullite needs to be reviewed. A description of the crystal structure of mullite must consider both the chemical composition and the degree of ordering. This is of particular importance for applications such as advanced ceramics, because the physical properties depend on the intrinsic structure of mullite.
    Keywords: Al/Si orderingvacancy orderingceramicssuperspaceincommensurate structures
    Electronic ISSN: 2052-2525
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...