AlO₂₄Se₈VZr₂

Architectural potential

An aluminium-selenium-vanadium-zirconium heavy-oxide ceramic fired at 1250 °C, carrying an unusual 300 MPa of compression for its family and the visible-absorber flag. Three hundred megapascals lifts it out of the decorative register and into load-capable territory — a compressive performance a clay brick cannot approach, carried in a body designed to soak up solar gain rather than reflect it. The CO₂ runs more than four times that of clay brick, so the argument is thermal capture plus compression rather than environmental replacement. Natural placements are south-facing trombe-wall infill blocks where the grey-blue body is wanted as a visible thermal absorber, hypocaust floor-slab elements carrying passive solar heat into radiant release, thick thermal-mass courses in entry vestibules facing east or south, and bracket-stones in landscape architecture where compression and heat-battery behaviour are both desired. The 85×85×38 mm slab format and 500 g workshop ceiling keep specification at the single-element or small-run scale. The caveat is the selenium fraction: Se is both a supply-chain bottleneck (the score sits at zero) and a workshop-safety concern — peak firing has to happen in a well-ventilated kiln, with off-gas handling rather than open-air exhaust.

Material character

The slab reads a cool grey-blue with the muted mineral register of a heavy-oxide body rather than the saturated colour of a glass absorber. At 3.61 g/cm³ in an 85×85×38 mm format the piece takes a deliberate two-handed lift, noticeably lighter than the bismuth and tungsten siblings of the same family and closer to a fired stoneware paver in hand-feel. Surface vitrified matte from the 1250 °C fire; edges cold-cut, the kerf powder pale against the grey-blue body. A 1.56 eV absorption edge sits well below the visible band, so the body takes solar gain into itself in the expected visible-absorber way. Against the bismuth-yellow thermal-mass sibling the colour shift is complete.