Non-evaporable getters which work at high temperature generally consist of a film of a special alloy, often primarily zirconium; the requirement is that the alloy materials must form a passivation layer at room temperature which disappears when heated. Common alloys have names of the form St (Stabil) followed by a number:
- St 707 is 70% zirconium, 24.6% vanadium and the balance iron,
- St 787 is 80.8% zirconium, 14.2% cobalt and balance mischmetal,
- St 101 is 84% zirconium and 16% aluminium.
In tubes used in electronics, the getter material coats plates within the tube which are heated in normal operation; when getters are used within more general vacuum systems, such as in semiconductor manufacturing, they are introduced as separate pieces of equipment in the vacuum chamber, and turned on when needed.
It is of course important not to heat the getter when the system is not already in a good vacuum.
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