Er₂K₁₀O₈

Architectural potential

An erbium-rich potassium oxide in the signal-bearing ceramic register, carrying a specific and narrow luminescent signature — erbium's characteristic green up-conversion under infrared and red lines under UV. At 100 MPa and four times the embodied CO₂ of a fired clay brick, this cannot be specified as a volume element; the whole architectural argument rests on the Er³⁺ emission. Natural placements are emergency-marking tiles in stair-cores and escape corridors where the green signal reads unmistakably under low-light excitation, wayfinding plaques in exhibition architecture, accent cladding patches at named thresholds, and specialty tiles in bath-house and crematoria interiors where ritual use makes sense of a signalling material. The 300 g workshop ceiling and the supply-chain score of 0.14 place specification firmly in the single-plaque register. Against its rare-earth siblings, erbium's green emission is the most legible of the luminescent palette — a functional choice when the signal itself, not the colour of the rest state, is the architectural argument. The caveat is cost: €81.53 per 100 g is the most expensive entry in this batch of rare-earth ceramics by a wide margin, reflecting erbium's narrow supply base — specification has to be a single named moment rather than a repeated element.

Material character

The 85×85×44 mm slab reads a neutral warm white with a very faint pink cast — the characteristic rose bloom of an erbium-oxide body, subtly distinct from the whiter yttrium-samarium sibling. Under 365 nm excitation the face lifts into a saturated green, the Er³⁺ line emission cleaner and more monochromatic than the broader orange of the praseodymium sibling. Vitrified matte skin from the 1200 °C fire, with a finer grain than the manganese-bearing rare-earth ceramics. Edges cold-cut, diamond kerf. At 3.12 g/cm³ the slab lifts two-handed but without real effort — lighter in hand than the denser rare-earth samarium slabs, closer to a conventional stoneware register.