Abstract
Silicon, a high melting point, low expansivity, cubic material which can be obtained readily in high purity form, provides an excellent thermal expansion standard. Various absolute determinations of the thermal expansivity of both single crystal and polycrystalline silicon are used to establish a smooth relationship from 90 to 850 K which is believed to be reliable to roughly 10−8 K−1, and which is extrapolated to 1000 K. Values also are suggested for temperatures to absolute zero. Key words: high temperature expansivity; silicon; standard expansivities; thermal expansivity.