Amorphisation at Heterophase Interfaces

Gemming, Sibylle; Enyashin, Andrey N.; Schreiber, Michael

doi:10.1007/3-540-33541-2_13

Cited by 2 publications

(2 citation statements)

References 94 publications

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“…This structure type is very similar to the AlB 2 type, but with a puckered Si sublattice, inducing a translationengleiche transition. Reports about this structure type refer to binary alkaline earth disilicides at nonambient conditions (Evers et al, 1977b;Bordet et al, 2000;Brutti et al, 2006) or with mixed R sites (Eisenmann et al, 1970;Evers et al, 1979) as well as theoretical considerations about the puckering only (Gemming & Seifert, 2003;Gemming et al, 2006;Enyashin & Gemming, 2007;Flores-Livas et al, 2011). As these reports do not meet the requirements of experiments at ambient conditions, we did not consider this group of compounds within this work.…”

Section: Structural Relationshipsmentioning

confidence: 99%

Structure variations within RSi₂ and R ₂ TSi₃ silicides. Part I. Structure overview

Nentwich

Zschornak

Sonntag

et al. 2020

Acta Crystallogr B Struct Sci Cryst Eng Mater

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Here, structural parameters of various structure reports on RSi2 and R2TSi3 compounds [where R is an alkaline earth metal, a rare earth metal (i.e. an element of the Sc group or a lathanide), or an actinide and T is a transition metal] are summarized. The parameters comprising composition, lattice parameters a and c, ratio c/a, formula unit per unit cell and structure type are tabulated. The relationships between the underlying structure types are presented within a group–subgroup scheme (Bärnighausen diagram). Additionally, unexpectedly missing compounds within the R2TSi3 compounds were examined with density functional theory and compounds that are promising candidates for synthesis are listed. Furthermore, a correlation was detected between the orthorhombic AlB2‐like lattices of, for example, Ca2AgSi3 and the divalence of R and the monovalence of T. Finally, a potential tetragonal structure with ordered Si/T sites is proposed.

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Section: Structural Relationshipsmentioning

confidence: 99%

Structure variations within RSi₂ and R ₂ TSi₃ silicides. Part I. Structure overview

Nentwich

Zschornak

Sonntag

et al. 2020

Acta Crystallogr B Struct Sci Cryst Eng Mater

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“…The RSi 2 and R 2 TSi 3 compounds with divalent R element can form with structure type EuGe 2 , as recent theoretical or high-pressure studies show (Evers et al, 1977b;Bordet et al, 2000;Brutti et al, 2006;Eisenmann et al, 1970;Evers, 1979;Gemming & Seifert, 2003;Gemming et al, 2006;Enyashin & Gemming, 2007;Flores-Livas et al, 2011). However, those reports are outside the scope of the present article focusing on experimental reports at standard conditions.…”

Section: The Formal Coordination Number and Zintl Phasesmentioning

confidence: 86%

Structure variations within RSi₂ and R ₂Si₃ silicides. Part II. Structure driving factors

Nentwich

Zschornak

Sonntag

et al. 2020

Acta Crystallogr B Struct Sci Cryst Eng Mater

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To gain an overview of the various structure reports on RSi 2 and R 2 TSi 3 compounds (R is a member of the Sc group, an alkaline earth, lanthanide or actinide metal, T is a transition metal), compositions, lattice parameters a and c, ratios c/a, formula units per unit cell, and structure types are summarized in extensive tables and the variations of these properties when varying the R or T elements are analyzed. Following the structural systematization given in Part I, Part II focuses on revealing the driving factors for certain structure types, in particular, the electronic structure. Here, concepts of different complexity are presented, including molecular orbital theory, the principle of hard and soft acids and bases, and a Bader analysis based on Density Functional Theory calculations for representatives of the reported structure types. The potential Si/T ordering in different structures is discussed. Additionally, the influences from intrinsic and extrinsic properties (e.g. elemental size and electronics as well as lattice parameters and structure type) are investigated on each other using correlation plots. Thermal treatment is identified as an important factor for the ordering of Si/T atoms. Nentwich et al. RSi 2 and R 2 Si 3 silicides. Part II. 379 research papers 380 Nentwich et al. RSi 2 and R 2 Si 3 silicides. Part II. Acta Cryst. (2020). B76, 378-410Figure 2R-T diagram of the RSi 2 and R 2 TSi 3 compounds. (a) normalized lattice parameter a, (b) normalized lattice parameter c, (c) normalized ratio c/a of lattice parameters, (d) shortest Si-T bonds, (e) ratio of atomi radii r T,Si /r R , (f) electronegativity difference EN(Si,R), (g) range of ordering, (h) thermal treatment, (i) density and (j) valence electron concentration. The used markers symbolize the crystal system: hexagon -hexagonal AlB 2 -like systems, open star -orthorhombic, AlB 2 -like systems, diamond -tetragonal ThSi 2 systems, elongated diamond -orthorhombic GdSi 2 systems. The lattice parameters a and c of the subplots (a) and (b) are normalized to the R-R distances within a/b and along c, respectively, to provide comparability.Accordingly, the ratio c/a in subplot (c) is also based on these normalizations. The shortest Si/T bonds in subplot (d) are calculated based on the formula (1). Subplot (e) depicts the ratio of atomic radii q rad , which is based on equation (2). Subplot (f) shows the electronegativity difference for the evaluation of the Zintl conditions. For the range of ordering n in subplot (g), a structure with disordered Si/T sites is marked with a black symbol, otherwise the color stands for the range of ordering n. For the thermal treatment (h), the color represents the temperature and the circle size the time of the treatment (triangle if unknown). Application of the floating zone method is marked with a black dot *, while no treatment is marked with a cross Â. The plots for the theoretical properties vec and ratio of radii were completed for not experimentally determined compounds (small circles) (Riedel & Janiak, 2011...

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Amorphisation at Heterophase Interfaces

Cited by 2 publications

References 94 publications

Structure variations within RSi₂ and R ₂ TSi₃ silicides. Part I. Structure overview

Structure variations within RSi₂ and R ₂ TSi₃ silicides. Part I. Structure overview

Structure variations within RSi₂ and R ₂Si₃ silicides. Part II. Structure driving factors

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Amorphisation at Heterophase Interfaces

Cited by 2 publications

References 94 publications

Structure variations within RSi2 and R 2 TSi3 silicides. Part I. Structure overview

Structure variations within RSi2 and R 2 TSi3 silicides. Part I. Structure overview

Structure variations within RSi2 and R 2Si3 silicides. Part II. Structure driving factors

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Structure variations within RSi₂ and R ₂ TSi₃ silicides. Part I. Structure overview

Structure variations within RSi₂ and R ₂ TSi₃ silicides. Part I. Structure overview

Structure variations within RSi₂ and R ₂Si₃ silicides. Part II. Structure driving factors