With a microhardness arrangement which is constructed as an accessory equipment for modern material testing machines the generation of Vickers indentation is investigated by recording of the load during a programmed penetration of the pyramide. For all engineering materials investigated the relation between load L and penetration depth p could be fitted by L=a1p ± a2p2 with a high degree of statistical reliability. It is derived a new hardness number which is independent of the load also in the microhardness region. By comparison it can be shown that conventionally measured Vickers hardness numbers are identical for the ductile metals but to large for brittle materials. Furtheron it is possible to determine quantitatively the change of the hardness of the surface layer disturbed by mechanical polishing. By the same experiment it is investigated in microregions of the different materials the inelastic behaviour by stress relaxation and the elastic recovery by measurement of the L‐p relation during unloading.

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Spin–lattice relaxation time measurements of Na23 in the temperature range of 160 to 360 °C for different Ca++‐doped crystals (35, 79, 170, 200, 700 ppm) show after subtracting the part related to the lattice vibrations that both isolated cation vacancies and vacancies associated with Ca++‐ions make a contribution to the relaxation contrary to existing proposals taking into account only one kind of vacancies. For the motion enthalpy of a vacancy around the impurity ion one obtains 0·69 eV, for the motion enthalpy of a isolated vacancy 0·75 eV which are in good agreement with results from other methods.

The aggregation of point defects is investigated by means of nuclear magnetic resonance (NMR), dielectric losses, and ionic conductivity measurements. The isothermal dipole concentration curves may be described with the help of a dimer—trimer model including dissolution of both aggregates. For NaCl crystals doped with 250 ppm SrCl2 the association enthalpy of dimers H2 = 0.40 eV is calculated and the association enthalpy of trimers H3 = (0.60 to 0.65) eV by fitting the experimental values.

The formation and association energies for the different aggregates of divalent metal impurities and cation vacancies are derived by considerations of the sums over all lattice vectors. This gives a simple formula in the point charge approximation if an infinite lattice is assumed. Because of the neglection of the polarization of the ions this method yields a higher value for these energies, as a comparison with the literature for the case of dipoles shows. But nevertheless it is a first possibility for a correct estimation of these energies also for higher aggregates.Bildungs-und Assoziationsenergien fur die verschiedenen Aggregate aus 2-wertigen Verunreinigungen und Kationenleerstellen werden durch Betrachtungen der Summen iiber alle Gittervektoren abgeleitet. Dies fuhrt zu einer einfachen Formel in Punktladungsniiherung fur ein unendlich ausgedehntes Gitter. Das Verfahren liefert wegen der Vernachliissigung der Polarisation der Ionen zwar systematisch zu hohe Werte fur diese Energien, wie ein Vergleich mit den aus der Literatur bekannten Werten fur Dipole zeigt, ergibt jedoch erstmals die Moglichkeit fur eine korrekte Abschiitzung dieser Energien auch fur hohwe Aggregate.