O₂₀Sr₁₀TiV₄

Architectural potential

A strontium-vanadium perovskite fired at 1300 °C, carrying 100 MPa of compression and a vanadium-dioxide thermochromic layer. The CO₂ runs more than four times that of a fired clay brick and the extreme-fire peak adds to the energy bill, so any argument for its use has to be paid for by the chromism rather than by mass. Above 68 °C the vanadium site switches from semiconductor to metal and the body darkens; below it, the body clears again — a self-regulating solar-control tile without wiring, sensors or mechanical shading. Natural placements are small-area overlays on south-facing greenhouse and conservatory glazing, patch-scale tiles around skylight perimeters in atria to modulate hottest-hour gain, accent courses in double-skin façades, and ceiling-tile patterns in day-lit halls that shift register through the warming day. At 200 g per batch, specification sits at the signature-accent scale rather than the envelope scale. Against the V-doped perovskite sibling of the atlas the grey-blue resting colour is cooler and denser. The caveat is the CO₂ and energy ledger plus the supply-chain score at zero — vanadium availability and 1300 °C kiln logistics together forbid any use beyond the small patch or the signature element.

Material character

At room temperature the slab reads a deep grey-blue, cooler and more mineral than the V-titanate sibling of the atlas. A 0.62 eV absorption edge sits deep in the infrared, so the visible colour is carried by the titanate lattice rather than by the vanadium fraction itself. At 4.92 g/cm³ in an 85×85×28 mm format the slab is heavy for its thinness, resisting the single-handed lift. Surface vitrified matte from the 1300 °C fire; edges cold-cut with diamond-saw kerf powder. The room-temperature state is what the camera records; the post-transition darker state belongs in a heated companion shot taken above 68 °C.