Cu₄Nb₆S₁₁Se
sulfide metal composite · sulfide low tempCu4Nb6S11Se1 is a sulfide metal composite suitable as sulfide low temp. Color: green-red-copper. Fired at 130°C from 4 precursors (Nb2O5, S, CuO). Workshop batch: 300g at €42.93. 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
- 5.24 g/cm³
- crystal
- monoclinic
- band gap
- 0.01 eV
- cost
- €143.10/kg · €42.93 / 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 hotplate-cast sulfide composite in the same zero-kiln register as the flagship polysulfides, here carrying niobium-selenide content that gives it a denser, more metallic handling than a pure copper-sulfide cast. At 350 MPa of compression and 130 °C forming temperature, the material reaches cement-equivalent structural presence without the kiln, and drives embodied CO₂ down by eighty-nine per cent against Portland. Natural placements are the detail-scale and specialty-tile register: thick cast floor tiles for workshop and gallery interiors, acoustic-wall inlay panels where mass without firing is wanted, decorative threshold slabs in retrofit carpentry, pavilion-scale cladding tiles in cold-country fabrication where kiln access is absent. The niobium content opens the register toward superconductor-adjacent coloration — a deeper, more metallic green-red-copper face than the manganese-copper siblings — and the cast forming supports embedded elements (timber inserts, metal mesh, temperature-sensitive additives) that no kiln-fired body could tolerate. Making-culture sits closer to a chemistry bench than to a brickyard. The caveat is cost: €42.93 per 300 g batch puts this in the signature-element register rather than bulk tile production, and saw-cutting the cast piece releases sulphide odour so workshop ventilation must be genuinely adequate, not nominal.
Material character
The niobium-selenide content shifts the matrix toward a darker, more saturated green-red-copper than the manganese-copper siblings — there is a cooler green undertone present that the pure copper-sulfide casts do not carry. At 5.237 g/cm³ and 70×70×39 mm the slab sits heavy in the single-hand grip, substantial but not two-handed. Surface is mold-matte with the characteristic meniscus sheen of a hotplate cast; edges as-cast, mildly reflective at the ninety. A fine sulphur bloom is present across the face, finer than on the copper-heavy casts, legible only under raking light. Against the flagship Cu-Mn-Na sibling the body reads cooler and more metallic.
Recipe
300 g batch · peak 130 °C| element | precursor | formula | mass | safety |
|---|---|---|---|---|
| Cu | copper(II) oxide (black) | CuO | 26.64 g | safe |
| Nb | niobium pentoxide | Nb2O5 | 66.75 g | moderate |
| Se | selenium (elemental) | Se | 6.61 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