Al₄Bi₄O₂₄Te₃W
heavy oxide ceramic · thermal mass ceramicAl4Bi4O24Te3W1 is a heavy oxide ceramic suitable as thermal mass ceramic. Color: yellow-photochromic. Fired at 1250°C from 3 precursors (Bi2O3, WO3, Al2O3). Workshop batch: 200g at €15.04. Compressive strength ~100 MPa; estimated 0.94 kg CO₂/kg (+326% vs clay brick). Notable: photochromic, electrochromic tungstate, visible absorber. Confidence: medium.
- forms at
- 1250 °C · high-fire
- replaces
- clay brick
- CO₂
- 326% higher than clay brick (0.94 vs 0.22 kg CO₂/kg; 4.3× higher)
- energy
- 108% higher than clay brick (6.25 vs 3.00 MJ/kg; 2.1× higher)
- compressive
- 100 MPa
- density
- 6.83 g/cm³
- crystal
- monoclinic
- band gap
- 2.41 eV
- cost
- €75.20/kg · €15.04 / 200 g batch
- confidence
- medium (synthesis route)
- potential
- 0.40 · env 0.00 · novel 1.00 · struct 0.20 · lineage 0.80 · supply 0.00
- flags
- photochromic: Darkens reversibly under UV. Glazing and surface layers that shade themselves on sunny days and clear when the sun drops — passive solar-gain control without mechanical shading. electrochromic tungstate: A voltage-switchable optical chemistry. In thin-film form a small DC signal shifts transmission from clear to tinted blue, opening the door to dimmable glazing and responsive partitions that do not need mechanical shading. visible absorber: A real-colour solar-gain control layer. Where the body takes visible light into itself rather than reflecting it, the material becomes a selective heat collector — useful on thermal-mass walls, absorber panels, and warm-toned cladding.
Architectural potential
A bismuth-tellurium aluminate with tungsten loading, carrying a triple functional chemistry — photochromic darkening under UV, voltage-switchable electrochromic tungstate response, and real-colour visible-absorber solar-gain behaviour — packaged in a heavy heat-storing ceramic body. The architectural argument is temporal and optical: this is a responsive tile that reads the sun across the day, darkening on bright afternoons without wiring, switching tint under a small DC signal, and storing daytime heat for slow release after dark. Natural placements are south-facing trombe-wall infills in passive-solar houses, absorber panels in double-skin façades over offices and schools, skylight-perimeter tiles in atria where daylight governs both heat and glare, and dimmable partition inserts in gallery spaces. The 500 g workshop ceiling constrains specification to patch and small-panel scale rather than whole-wall composition. Against a fired clay brick the embodied CO₂ runs four times higher and firing energy runs double, so this is strictly a functional overlay — a tile that earns its carbon cost by doing three things no ordinary ceramic does. The caveat is procurement: the supply-chain score sits at zero, meaning tellurium and tungsten precursor availability is effectively bottlenecked, and specification has to start with a verified sourcing line.
Material character
The 70×70×30 mm slab reads a warm mustard-yellow in the rest state, bismuth and tungsten together driving a honey tone across the face. Under sustained UV exposure the photochromic response shifts the body toward a deeper amber-olive, and the reverse clears within minutes in shade. Surface vitrified from the 1250 °C fire, with a faint glassy sheen at grazing angles — the tungsten contribution pulls the skin closer to glaze than to pure ceramic matte. Edges cold-cut, diamond kerf. At 6.83 g/cm³ the slab is heavy for its footprint — clearly denser than the rare-earth siblings at similar size, and sits firmly on the bench with a deep low ring under the tap.
Recipe
200 g batch · peak 1250 °C| element | precursor | formula | mass | safety |
|---|---|---|---|---|
| Al | calcined alumina | Al2O3 | 14.91 g | safe |
| Bi | bismuth(III) oxide (yellow) | Bi2O3 | 68.14 g | moderate |
| W | tungsten trioxide (yellow) | WO3 | 16.95 g | moderate |
- 1Ramp
- 2Hold
- 3Ramp
- 4Ramp
- 5Hold
- 6Ramp
- 7Ramp
Photochromic — reversibly darkens under UV exposure
Electrochromic — color switches under applied voltage (thin-film chemistry)
Visible absorber — saturated color from bandgap in the visible range