Potassium self-diffusion in a K-rich single-crystal alkali feldspar

The paper reports potassium diffusion measurements performed on gem-quality single-crystal alkali feldspar in the temperature range from $1169$ to 1021 \, \mbox{K}. Natural sanidine from Volkesfeld, Germany was implanted with \mbox{}^{43}\mbox{K} at the ISOLDE/CERN radioactive ion-beam facility normal to the (001) crystallographic plane. Diffusion coefficients are well described by the Arrhenius equation with an activation energy of 2.4 \, \mbox{eV} and a pre-exponential factor of 5\times10^{-6} \, \mbox{m}^{2}/\mbox{s}, which is more than three orders of magnitude lower than the \mbox{}^{22}\mbox{Na} diffusivity in the same feldspar and the same crystallographic direction. State-of-the-art considerations including ionic conductivity data on the same crystal and Monte Carlo simulations of diffusion in random binary alloy structures point to a correlated motion of K and Na through the interstitialcy mechanism

'Elbflorenz'. Zur Geschichte des Beinamens im Kontext toponymischer Konkurrenten

Very different opinions on the origin of Dresden's byname Elbflorenz, have been given. Based on much diverse evidence this paper explores the conditions and the genesis of this allonym in connection with comparative place-names. Local written records limit the time of origin of the byname and extensively document its widespread reception

Unsere geschützte Natur

Anliegen dieses Faltblattes ist es, bei der interessierten Öffentlichkeit Verständnis für die Ziele des Naturschutzes zu erreichen und die zum Schutz von Natur und Landschaft unverzichtbaren Schutzgebietskategorien und Kriterien vorzustellen