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A synthesis route for the preparation of optically transparent magnesium fluoride sols using magnesium acetate tetrahydrate as precursor is described. The obtained magnesium fluoride sols are stable for several months and can be applied for antireflective coatings on glass substrates. Reaction parameters in the course of sol synthesis are described in detail. Thus, properties of the precursor materials play a crucial role in the formation of the desired magnesium fluoride nanoparticles, this is drying the precursor has to be performed under defined mild conditions, re-solvation of the dried precursor has to be avoided and addition of water to the final sol-system has to be controlled strictly. Important properties of the magnesium fluoride sols like viscosity, particle size distribution, and structural information are presented as well.

Porous MgF 2 is a highly promising film material for the preparation of durable antireflective coatings. Synthesis routes based on Mg(OMe) 2 and Mg(OAc) 2 precursors are described, and the resulting sol-gel films and their thermal consolidation are compared using thermal analysis (TGA/DTA), scanning electron microscopy, ellipsometric porosimetry and X-ray diffraction. Due to their constant viscosity, Mg(OAc) 2 -based coating solutions are superior from the practical point of view. The porous films are stable against degradation under the steady-state temperature humidity life test (85/85), and they can successfully be integrated into TiO 2 -MgF 2 -TiO 2 interference filters. Graphical Abstract Porous MgF 2 antireflective k/4 coatings were prepared by sol-gel processing. Synthesis routes based on Mg(OMe) 2 and Mg(OAc) 2 precursors are established, and the properties of the resulting film materials are compared, respectively.

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Magnetic, bathymetric and seismic reflection profiler data are described from the accessible central and eastern parts of the Weddell Sea. The shape consistency of the magnetic anomalies is not good, but the profiles show magnetic lineations trending slightly north of east over almost all of the area surveyed. The lineations are undulating, and a small reflection profiler survey has revealed the presence, in the northern Weddell Sea, of several closely spaced, small-offset fracture zones trending north-west to west-northwest. The amplitude of the fracture zone topography increases northward as the fracture zone orientation becomes more oblique to the gross orientation of the magnetic anomalies. Two synthetic magnetic anomaly profiles, each providing a reasonable fit to the observed anomalies, are used to argue that neither the quality of the data set nor the existing level of understanding of the regional tectonic environment is adequate as yet to support either an unambiguous age for the Weddell Sea or a model for its evolution.