Temperature distribution in a cylindrical lengthy workpiece under plasma electrolytic heating

The article focuses on developing a model of a stationary temperature field inside a semi-infinite cylindrical sample partly immersed in electrolyte. Temperature calculation is carried out by solving a heat transfer equation separately for the immersed and protruding parts of the sample. The heat flux is set on the outer area boundaries; meanwhile heat flux density for the immersed part is linearly dependent on the vertical coordinate. Within the framework of the model, vertical and radial temperature gradients are worked out both in protruding and immersed parts of the anode. It has been established that the vertical coordinate of the sign reversal point of the heat flux density in the immersed part depends on heat exchange conditions in the protruding part.

On the Origin of the Anomalous Sign Reversal in the Hall Effect in Nb Thin Films

We re-visit the anomalous sign reversal problem in the Hall effect of sputtered Nb thin films. We find that the anomalous sign reversal in the Hall effect is extremely sensitive to a small tilting of the magnetic field and to the magnitude of the applied current. Large anomalous variations are also observed in the symmetric part of the transverse resistance R xy . We suggest that the surface current loops on superconducting grains at the edges of the superconducting thin films may be responsible for the Hall sign reversal and the accompanying anomalous effects in the symmetric part of R xy .

The riddle of orange–red luminescence in Bismuth-doped silica glasses

For over the past two decades it has been believed that the intense orange-red photoluminescence in Bismuth-doped materials originates from Bi$$^{2+}$$ 2 + ions. Based on the results from magnetic circular polarization experiments, we demonstrate that this hypothesis fails for Bismuth-doped silica glasses. Our findings contradict the generally accepted statement that the orange-red luminescence arises from $$^{2}P_{3/2}(1)$$ 2 P 3 / 2 ( 1 ) $$\rightarrow$$ → $$^{2}P_{1/2}$$ 2 P 1 / 2 transition in a divalent Bismuth ion. The degree of magnetic circular polarization of this luminescence exhibits non-monotonic temperature and field dependencies, as well as sign reversal. This complex behaviour cannot be explained under the assumption of a single Bi$$^{2+}$$ 2 + ion. The detailed analysis enables us to construct a consistent diagram of energy levels involved in the magneto-optical experiments and propose a new interpretation of the nature of orange-red luminescence in Bismuth-doped silica glass. A centre responsible for this notorious photoluminescence must be an even-electron system with an integer total spin, presumably a dimer of Bismuth ions or a complex consisting of Bi$$^{2+}$$ 2 + and an oxygen vacancy.