Rutiletype

Rutiletype refers to a crystallographic structure type used by a broad class of oxides with the formula MO2, named after the prototypical oxide TiO2 in its rutile form. It is a standard reference structure in solid-state chemistry and mineralogy for describing tetragonal oxide lattices.

The rutile-type structure is tetragonal, with space group P4_2/mnm, and contains two formula units per conventional unit cell. In this arrangement, the metal cation M is six-coordinate, forming distorted MO6 octahedra. These octahedra share edges along the c axis and connect through common corners in the a–b plane to create a robust three-dimensional oxide framework. Each oxide anion O2− is coordinated to three metal cations, and chains of octahedra extend along the c axis, contributing to anisotropic physical properties. Typical lattice parameters for TiO2 in the rutile form are approximately a ≈ 4.59 Å and c ≈ 2.96 Å, yielding c/a around 0.64.

Rutile-type structures are common among numerous MO2 compounds beyond TiO2, including SnO2 (cassiterite) and RuO2, with variations produced by ionic substitutions that form rutile-type solid solutions. The structure is often retained under specific temperature or pressure conditions, and some related oxides can adopt the rutile-type arrangement as a high-temperature or high-pressure polymorph.

In materials science, rutile-type oxides are studied for their electronic, optical, and catalytic properties. Substituting different metal cations within the rutile framework enables tuning of conductivity, refractive index, and catalytic activity, making the rutile-type motif a widely used reference for describing and engineering oxide materials.