CuS₁₆V₉
sulfide metal composite · sulfide low tempCu1S16V9 is a sulfide metal composite suitable as sulfide low temp. Color: green-red-copper. Fired at 130°C from 3 precursors (V2O5, S, CuO). Workshop batch: 300g at €25.39. Compressive strength ~350 MPa; estimated 0.09 kg CO₂/kg (-89% vs Portland cement). Notable: forms without a kiln. Confidence: medium.
- forms at
- 130 °C · hotplate · no kiln
- replaces
- portland cement
- CO₂
- 89.1% lower than Portland cement (0.09 vs 0.83 kg CO₂/kg)
- energy
- 89.1% lower than Portland cement (0.60 vs 5.50 MJ/kg)
- compressive
- 350 MPa
- density
- 4.05 g/cm³
- crystal
- trigonal
- band gap
- 0.01 eV
- cost
- €84.63/kg · €25.39 / 300 g batch
- confidence
- medium (synthesis route)
- potential
- 0.80 · env 1.00 · novel 1.00 · struct 0.70 · lineage 0.50 · supply 0.46
- flags
- zero kiln: Forming happens without firing — the material cures through chemistry at ambient or hotplate temperature. At building scale this removes the kiln from the supply chain: on-site casting, regional workshops, cold-country fabrication all become available.
Architectural potential
A second flagship for the kiln-free compression register, cast at 130 °C on a hotplate and reaching 350 MPa — cement-grade load capacity with an eighty-nine-per-cent cut in embodied CO₂ against Portland. The copper-vanadium-sulphur matrix opens a particular architectural register: heavy cast thresholds, interior floor tiles for gallery and workshop interiors, cast laminate layers bonded onto plywood substrates, and drop-cast inlay panels in joinery and cabinet-work. Because forming happens below boiling, form-work can be plywood, silicone, or lost-wax — the usual chemistry-lab repertoire rather than the kiln yard. At the 300 g batch scale it belongs in the detail register: decorative sill plates, poured bench-tops for bathing rooms, heavy acoustic-panel inlays for concert-hall foyers, skirting-level cast thresholds in retrofit carpentry. The substitution argument against Portland is sharp at small volumes, since every kilogram cast displaces cement without firing. At 1000 g workshop ceiling the realistic envelope is a tile-scale piece rather than a wall element. The caveat is two-part: copper raises raw-material cost to €25 per 300 g, and like every cast polysulfide in the family the workshop needs active sulphide-odour ventilation during saw-cutting and surface dressing — making production logistics closer to a chemistry bench than a masonry yard.
Material character
The 85×85×34 mm slab sits dense in the hand at 4.05 g/cm³ — a clear weight step above the vanadium-light sulphides, firmly two-hand lift despite the modest footprint. Colour reads a mottled green-copper-red: the copper threads run warm through a cooler vanadium-green ground, with the S₁₆ sulphur phase surfacing as fine bloom under raking light. Mould-matte finish with the meniscus sheen of a cast face; edges come as-cast, slightly reflective where the slurry settled against the form. Against the manganese-sodium sulphide sibling the V₉ body reads noticeably greener and harder-edged, and the fracture surface is closer to vitreous than crumbly.
Recipe
300 g batch · peak 130 °C| element | precursor | formula | mass | safety |
|---|---|---|---|---|
| Cu | copper(II) oxide (black) | CuO | 8.86 g | safe |
| V | vanadium pentoxide | V2O5 | 91.14 g | moderate |
- Pre-heatHotplate to 150 °C
- MeltSulfur liquefies at 115 °C; full liquid at 130 °C
- CastPour at 140–145 °C
- SetRoom temperature 30 min (firm) → 24 h (full strength)
Zero-kiln process — 130 °C hotplate cast only