Uniformity Characterization of Lattice Spacing of 28Si Single Crystals

The uniformity of the lattice spacing of
²⁸
Si enriched single crystals was investigated by the self-referenced lattice comparator (SRLC). Mapping measurements of the lattice spacing were performed for samples cut from two
²⁸
Si ingots produced recently by PTB. Only faint patterns were observed, and two samples, Si28-24Pr11 M.1 and Si28-31Pr11 M.1, have uniform distribution of lattice spacing. Both ingots were expected to be suitable for the realization of the kilogram.