Fehlordnungen im Aufbau kristalliner Stoffe, bestimmt aus Gitterkonstanten und Dichtemessungen

Abstract

In this article a summary of tlie first attempts to détermine n' (the actual number of molecules per unit cell in contrast to n, which gives the number of molecules in an ideal or sound lattice) by precision determination of the volume v of the unit cell, of the macroscopie density d of the substance and of its molecular weight M is given. The calculations of n' were made using the well known equation n' = vdN₀/M, where N₀ is the Avogadro Number. The methods of determination of v, d and M from experimental measurements and the errors of these determinations are discussed. The total error connected with the computation of n’ and its significance is also mentioned.

The method permits to determine only an excess of interstitials or an excess of vacant sites in the lattice. At present the precision of such determinations is for instance in case of aluminum ± 8 atoms per 10,000 unit cells. If the number of defects calculated exceeds the number determined from error calculation, the respective defects are regarded to be present in the crystalline substance.

Attempts are made to explain strain hardening of aluminum and the width of certain phases in binary systems by the accumulation of interstitials and by the formation of vancancies.