Evaluation of the molar volume of silicon crystals for a determination of the Avogadro constant

For a determination of the Avogadro constant N/sub A/ by the X-ray crystal density (XRCD) method, the molar volume M//spl rho/ of three different silicon crystals, NRLM1, NRLM2, and NRLM4, have been analyzed systematically by measurements of their densities /spl rho/ and molar masses M. Details on the sample preparations and the result of measurement are presented.