Structural Inorganic Chemistry Review

Vocabulary flashcards based on the lecture notes from Structural Inorganic Chemistry.

Metallic phases that incorporate non-metal atoms (H, C, N) into the structure.

Interstitial Phases

The Hägg Border refers to the boundary condition for the formation of interstitial phases in alloys. It is mathematically expressed as the ratio of the atomic radius of the solute (rx) to the atomic radius of the solvent (rm) and is defined as rx/rm ≤ 0.59. This condition indicates that interstitial solid solutions can form only if the solute's atomic size is significantly smaller than that of the solvent, allowing for efficient packing and stability within the crystalline structure.

Hägg Border

A scale used to measure the hardness of minerals; interstitial phases have a hardness ≥ 8.5.

Mohs Hardness

Interstices in close-packed structures that can accommodate larger atoms, typically larger than tetrahedral holes.

Octahedral Holes

Interstices in close-packed structures that are approximately half the size of octahedral holes.

Tetrahedral Holes

The energy difference between the actual electron configuration of a transition metal ion and the hypothetical electron configuration in a purely ionic model.

Crystal Field Stabilization Energy (CFSE)

A type of spinel structure where metal cations occupy tetrahedral and octahedral sites in a predictable arrangement.

Normal Spinel

A type of spinel structure where metal cations exchange positions between tetrahedral and octahedral sites compared to the normal spinel.

Inverse Spinel

The rule stating that with increasing pressure, the coordination number of atoms tends to increase.

Pressure Coordination Rule

A phenomenon where increased coordination number corresponds to increased inter-atomic distances.

Pressure-Distance Paradox

A crystal structure formed by carbon atoms in which each carbon atom is tetrahedrally coordinated, resembling diamond.

Cubic Diamond Structure

Phases that occur in materials with interstitial atoms filling the gaps in metal structures, significantly affecting their properties.

Hägg-Phases

Interstitial and ionic carbides have different reactivities; ionic carbides can react with water while interstitial carbides do not.

Reactivity of Carbides

In carbides, the carbon-carbon bond length is typically 1.65 Å.

C-C Bond Length in Carbides

Interstitial phases are metallic phases that incorporate non-metal atoms (such as hydrogen, carbon, and nitrogen) into the metallic structure.

What are interstitial phases in materials science?

Hydrogen (H), Carbon (C), Nitrogen (N) are examples of non-metal atoms that can be incorporated into metallic structures to form interstitial phases

Examples of non-metal atoms that can form interstitial phases

Interstitial phases are metallic phases that occur when non-metal atoms—such as hydrogen (H), carbon (C), and nitrogen (N)—are incorporated into the crystalline structure of metals. This incorporation alters the properties of the metal, such as strength, hardness, and ductility, due to the changes in electronic structure and atomic spacing that these foreign atoms cause. Interstitial phases can significantly enhance the performance of materials, especially in applications like steel or superalloys, where the presence of carbon or nitrogen can improve tensile strength and resistance to wear.

What are interstitial phases in materials science?