Planetit

Planetit is a synthetic inorganic ceramic material with a dense, polycrystalline microstructure. It is composed chiefly of silicon- and aluminum-rich oxides, with minor amounts of magnesium, calcium, iron, and titanium, which confer a high melting point and chemical inertness. First described in laboratory literature in the 2010s, planetit was named for its potential to model planetary crust materials under extreme conditions.

Properties and structure: Planetit exhibits high hardness, excellent thermal stability beyond 1700°C, and a low coefficient of thermal expansion. It shows relatively high thermal conductivity for a ceramic and maintains dielectric stability across a broad temperature range. The grains are typically micrometric, with well-bonded grain boundaries that contribute to toughness.

Occurrence and synthesis: There are no confirmed natural Earth occurrences of planetit; it is produced in high-temperature synthesis experiments and under controlled sintering conditions, such as spark plasma sintering or hot-pressing. Some studies report tentative identifications of planetit-like inclusions in meteorites, but these findings remain contested.

Applications and significance: In planetary science, planetit serves as a reference material for simulating crustal phases under extreme conditions. In industry, its high-temperature stability and chemical inertness make it a candidate for heat shields, crucibles, and refractory components, though practical use depends on scalable production and cost.