Cr₃FeO₂₄W₄Y₄

Architectural potential

This is a passive thermal-battery ceramic that doubles as a voltage-switchable optical layer — heavy oxide tungstate body that absorbs daytime solar gain and re-releases it after dark, while a DC signal shifts its transmission between clear and tinted states. Natural placements are south-facing thermal-wall patches in passive-solar housing, trombe-wall infill tiles in greenhouses and hybrid conservatories, responsive glazing inserts in double-skin façades, switchable partition panels in hospital and laboratory interiors where dimmable separation is wanted without mechanical shading, and atrium ceiling tiles that dim actively at solar peak. The visible-absorber chemistry makes the body itself into a warm-toned thermal collector, shifting the thermal day the way a trombe wall does. But the embodied CO₂ at plus 326 per cent against clay brick forbids any bulk use: this is signature-tile and cladding-patch register, not wall-volume ceramic. At 100 MPa of compression the material is non-load-bearing in any primary-structure sense. The caveat is supply-chain: tungsten-yttrium-chromium-iron sourcing sits at a score of 0.0 in the atlas, meaning every raw input is sensitive. 1250 °C firing and 200 g workshop batches keep this firmly in the responsive-tile register.

Material character

The slab carries a deep saturated green body, the chromium-tungstate register distinct from any cobalt or vanadium green in the glass family — closer to oxidised verdigris than to bottle glass. At 6.48 g/cm³ and 70×70×31 mm the piece is dense and cold in the hand, a two-hand grip despite the small face — denser than any of the perovskite siblings in the atlas. Skin finishes vitrified and matte from the 1250 °C fire; edges cold-cut, the diamond-saw powder left along the kerf. Fully opaque. Under applied voltage the body shifts darker at the visible wavelengths — a slow blue-grey transition the camera should record in two states.