Conditions for existence of the L3 phase have been determined for a system containing water, n-hexanol, and the zwitterionic surfactant n-tetradecyldimethylamineoxide. Electric birefringence, light-scattering, rheology, and electrical-conductivity experiments were performed on this phase. Results are consistent with the existence of platelike micelles, whose diameter changes with surfactant concentration in such a way that it remains comparable to mean plate spacing. This behavior can be understood in terms of a previous L3 phase theory containing randomly oriented plates.

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Rod‐like micelles of perfluorosurfactants in aqueous solution were examined by using the transient and dynamic electric birefringence method. Tetraethylammoniumperfluoroctanesulfonat shows in the overlap region of the rods between 5 mM and 15 mM up to three different relaxation times τ1, τ2 and τ3 between a few μs and several ms. A forth very long relaxation time τ4 (seconds) appears at higher concentrations. The relaxation processes with the time constants τ1, τ3 and τ4 have a negative birefringence, while τ2 has a positive sign. In the anomaly region the total birefringence can change sign as a function of the total surfactant concentration and of the field strength. The anomalous behaviour of the time and frequence dependence of the electric birefringence is explained on the basis of intermicellar interaction. It is assumed, that the external electric field induces an additional anisotropic Lorentz‐field, which changes dramatically the local Lorentz‐field around the micelles. As a result both the correlation of the center of masses and the correlation of the rodlike micelles changes. This gives rise to the processes τ1, τ2 and τ3. The largest relaxation time τ4 seems to be due to a deformation and relaxation of a temporary network, which is built by the rodlike micelles.

Gittergeometrische Betrachtung der plastischen Verformung von LavesphasenDie Sprodigkeit vieler intermetallischer Verbindungcn auch bci metallischem Bindungscharakter 1aBt einen Zusammenhang mit der Gittergeometrie vermuten. Der EinfluB der Atomanordnung auf dns Gleiten der Versetzungen wird fur die Lavesphasengitter des MgZn,-Typs (C 14) und des MgCu,-Typs (C 15) vergleichend mit den dicht gepackten met,allischen Elementgitt*ern untersucht. Betrachtet werden die Anderung der Koordinationsverhaltnisse beim Gleiten, die Verzahnung der Ebenen im Model1 starrer Kugeln, mogliche Stapelfehler und Teilversetzungen und daraus die giinstigsteri Gleitebenen fur Ganzversetzungen mit stabilem bzw. gegen Dissoziation indifferentem Burgersvektor und Teilversetzungen ormittelt. Beim Schnoiden von gleitenden Stufenversetzungen wird erwartet, daB Zwischcngitteratome entstehen. Der Vergloich mit den Elementgittern legt den SchluB nahe, da13 die Sprodigkeit der Verbindungsgitter eine Folge der kornplizierten Atomanordnung ist.The brittleness of many intermetallic compounds even of tjhose of metallic bond is supposed to be related to the lattice geometry. The influence of the arrangement of stom9 on slip of dislocations has been investigated in case of the Laves phase lattices of MgZn, (C 14)-and MgCu, (C 15)-type of structure and is compared with the close packed lattices of metallic elements. Changes of coordination during slip, interpenetration of lattice planes in a hard sphere model, possible stacking faults, and partial dislocations have been considered. Prom there tho most favourable slip planes are derived for dislocations of the following characters: perfect dislocations of stable Burgersvectors and Burgersvectors indifferent to dissociation and imperfect dislocations. The formation of interstitial atoms during intersection of moving edge dislocations is suggested. In cornpaxison wibh the elemental lattices the brittleness of compound lattices is concluded t o be a consequence of the complicated arrangement of atoms.

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