skutterudite

Skutterudite is the name given to a cobalt arsenide mineral with the chemical formula CoAs3. It is part of the arsenide minerals and typically presents a metallic appearance with a gray to steel‑like color and a bright luster. Skutterudite forms as small crystals or masses in hydrothermal arsenic‑rich ore deposits and is commonly found associated with other arsenide and sulfide minerals. It was named after Skuterud, Sweden, the locality where the mineral first came to scientific attention.

In addition to the mineral, skutterudite refers to a broader class of compounds that share a related crystal framework. The materials class is often described by the formula RT4X12, where R is a filler atom (such as a rare-earth or alkaline-earth element), T is a transition metal, and X is a pnictogen (P, As, or Sb). These compounds crystallize in a cubic skutterudite structure that features large voids in the framework, which can be occupied by filler atoms. This structural characteristic is of particular interest in materials science because it can decouple electrical and thermal transport properties.

Skutterudites are studied for thermoelectric applications, where the goal is to convert heat into electricity. The presence of filler atoms can scatter lattice vibrations and lower thermal conductivity while preserving or enhancing electrical conductivity, leading to improved thermoelectric performance. Reported results in the literature include dimensionless figures of merit (ZT) near or above unity at elevated temperatures for some filled skutterudite compositions.

Overall, skutterudite denotes both a mineral with the formula CoAs3 and a versatile family of thermoelectric materials built on a shared crystal framework.