Structure variations within RSi₂ and R₂Si₃ silicides. Part II. Structure driving factors

Area of Science:

• Solid-state chemistry
• Materials science
• Crystallography

Background:

• RSi2 and R2TSi3 compounds exhibit diverse crystal structures.
• Understanding structure-property relationships is crucial for materials design.

Purpose of the Study:

• To systematically analyze structural properties of RSi2 and R2TSi3 compounds.
• To identify driving factors, particularly electronic structure, for observed structure types.
• To investigate the influence of elemental and extrinsic properties on crystal structures.

Main Methods:

• Compilation and analysis of extensive structural data (lattice parameters, c/a ratios, etc.).
• Application of theoretical concepts: molecular orbital theory, Hard and Soft Acids and Bases (HSAB) principle.
• Density Functional Theory (DFT) calculations with Bader analysis for representative compounds.
• Correlation analysis of intrinsic (elemental size, electronics) and extrinsic (lattice parameters, structure type) properties.

Main Results:

• Extensive tables summarize compositions, lattice parameters, and structure types.
• Electronic structure is identified as a key determinant of structure type.
• Potential for silicon/transition metal (Si/T) ordering is discussed.
• Interplay between elemental and extrinsic properties is visualized through correlation plots.
• Thermal treatment is found to be a significant factor influencing Si/T ordering.

Conclusions:

• The study provides a comprehensive overview and systematization of RSi2 and R2TSi3 structures.
• Electronic structure principles offer insights into the formation of specific structure types.
• Elemental and extrinsic factors significantly influence crystal structure variations.
• Controlled thermal treatment can be utilized to tailor Si/T ordering in these compounds.