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Material World
Application

Lighting

Converting electricity into visible light, historically by heating something until it glowed.

For a century, electric light meant heating a filament until it glowed — which wastes most of the energy as heat, and constrained the material choice to whatever survived white heat. Tungsten won that competition on melting point alone.

Solid-state lighting works differently, emitting light directly from a semiconductor junction, and the material constraint moved from melting point to band gap. Lighting is a significant fraction of world electricity demand, so the switch is consequential well beyond the fitting.

Medium confidence Weak evidence checked recently · only one source, so there is nothing to cross-check it against · stated directly by the source

How this connects

Where a connection has been confirmed by an outside reference, that reference is named beside it.

uses

  • Silicon — element · as the substrate beneath most LED electronics, though not the emitter itself
  • Arsenic — element · as gallium arsenide, in infrared and laser diodes
  • Gallium — element · gallium nitride is the emitter in every white LED
  • Germanium — element · in infrared optics rather than visible emission
  • Mercury — element · the vapour discharge in fluorescent tubes, now being phased out
  • Indium — element · as the transparent electrode in displays
  • Terbium — element
  • Tungsten — element · the incandescent filament, chosen for melting point alone
  • Yttrium — element · as the red phosphor in displays and lamps
  • Neon — element · the orange-red no phosphor or filter is needed to produce
  • Krypton — element · allows a hotter filament and a whiter light
  • Europium — element · the red and blue phosphor components in lamps and white LEDs
  • Yttrium aluminium garnet — compound · as cerium-doped powder over a blue LED die, absorbing some of the blue and re-emitting yellow so the mixture reads as white
  • Phosphor — material · every fluorescent lamp and every white LED — the diode makes blue and the phosphor makes the rest
  • Incandescent lamp — object · and almost all of the energy leaves as heat, which is inherent rather than a design failure and is why it was legislated away
  • Beeswax — material · and specifically the good end of it: beeswax burns brighter and far cleaner than tallow, which is why church and hall used it while households burned fat
  • Gallium nitride — compound · a blue GaN emitter behind a yellow phosphor is what every white LED actually is, and the displacement of incandescent lighting by LED is among the largest energy efficiency changes of the century

Sources

  • Material World
    Our own writing

Questions this page answers

Where it comes from, and what it becomes

Follow Lighting back to what it starts as, and forward into what it becomes. Each step is a documented one — a real route material takes, not a chain of inference.

Upstream — what it comes from

  • Lighting → uses (as the substrate beneath most LED electronics, though not the emitter itself) → Silicon → is produced by (carbothermic reduction of silica with coke in a submerged arc furnace, which is smelting in the strict sense even though no ore is involved) → Smelting → takes as input (as the element removed, not added) → Oxygen → is produced by (the largest output by tonnage, and the reason air separation units sit beside steelworks) → Air separation → takes as input (the feedstock, and an unusual one in being free, unlimited and available anywhere — the cost is entirely the energy to liquefy it) → Air
  • Lighting → uses (as gallium arsenide, in infrared and laser diodes) → Arsenic → is sourced from (recovered from the flue gases of copper and lead smelting, where it is a contaminant to be captured rather than a product to be sought) → Copper → is produced by (as blister copper, refined electrolytically afterwards) → Smelting → takes as input (as the element removed, not added) → Oxygen → is produced by (the largest output by tonnage, and the reason air separation units sit beside steelworks) → Air separation
  • Lighting → uses (gallium nitride is the emitter in every white LED) → Gallium → is sourced from (as a by-product of the Bayer process) → Bauxite → is sourced from (the residue of prolonged tropical weathering, which strips the silica and alkalis out of an aluminosilicate rock and leaves the aluminium behind — basalt is one common parent among several) → Basalt → is sourced from (partial melting of mantle peridotite is what basalt magma is — the residue left behind stays peridotite, depleted of what went into the melt) → Peridotite → is composed of (the mineral that defines the rock and gives it its name — a peridotite is olivine-dominant by definition) → Olivine
  • Lighting → uses (the incandescent filament, chosen for melting point alone) → Tungsten → is produced by (reduced from the oxide, at a temperature few other metals demand) → Smelting → takes as input (as the element removed, not added) → Oxygen → is produced by (the largest output by tonnage, and the reason air separation units sit beside steelworks) → Air separation → takes as input (the feedstock, and an unusual one in being free, unlimited and available anywhere — the cost is entirely the energy to liquefy it) → Air
  • Lighting → uses (as cerium-doped powder over a blue LED die, absorbing some of the blue and re-emitting yellow so the mixture reads as white) → Yttrium aluminium garnet → is produced by (pulled from a melt at close to 2,000 °C over days, with the dopant added to the charge so it enters the lattice as the crystal forms) → Czochralski process → takes as input (charged to the crucible already refined; the process changes its arrangement and its purity, not its identity) → Silicon → is produced by (carbothermic reduction of silica with coke in a submerged arc furnace, which is smelting in the strict sense even though no ore is involved) → Smelting → takes as input (roasted to drive off sulfur, then reduced to copper) → Chalcopyrite
  • Lighting → uses (every fluorescent lamp and every white LED — the diode makes blue and the phosphor makes the rest) → Phosphor → is produced by (the host lattice and the activator ion are fired together at high temperature, so the rare earth is built into the crystal rather than mixed with it) → Firing → takes as input (to 1200–1300 °C, which is the vitrification that separates it from earthenware — and it is a temperature rather than a recipe) → Stoneware → is sourced from (a clay that survives 1200 °C and above, which an earthenware clay does not) → Clay → is sourced from (clay is chiefly what feldspar becomes when it weathers) → Orthoclase

These are the most distinct paths back. Lighting can be traced through others besides.