[en] By stacking PbTe layers there is a non-monotonic topological phase transition as a function of the number of monolayers. Based on first principles calculations we find that the proper stacked crystal symmetry determines the topological nature of the slab. While a single PbTe monolayer has a nontrivial phase, external pressure can induce topological phase transition in bulk PbTe. Between these two limits, where finite size effects are inherent, we verified that, by applying an external pressure, odd stacking layers can be tuned easily to a topological phase, while even stacking keeps a larger band gap, avoiding band inversion. The quite distinct behavior for odd/even layer is due to the symmetry of the finite stacking. Odd layers preserve the bulk symmorphic symmetry with strong surface hybridization, while even layers belong to a nonsymmorphic group symmetry. Nonsymmorphism induces extra degeneracy reducing the hybridization, thus protecting band inversion, postponing topological phase transitions. (paper)

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[en] Quantitative information on the effect of temperature and thallium- and sodium impurity content in lead telluride on resonance-state band energy position is obtained from the data on the Hall effect presented in the previous paper

[en] The Cd impurity is studied for its influence on the free charge carrier concentation in PbTe crystals during their dopping in the process of growth depending on the amount of Te precepitates in them. It is determined that the excess of Te essentially decreases effectivity of the donor action of Cd in these materials. A variation of the free carrier concentration by this method of doping is in many cases considerably smaller than concentration of the introduced impurity. Possible reasons of the Cd donor action in PbTe are analysed

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[en] Confinement of radioactive and hazardous materials is one of the fundamental safety functions in a nuclear fusion facility, which has to limit the mobilisation and dispersion of sources and hazards during normal, abnormal and accidental situations. In a first step energy sources and radioactive source have been assessed for a conceptual DEMO configuration. The confinement study for the European DEMO has been investigated for the main systems at the plant breakdown structure (PBS) level 1 taking a bottom-up approach. Based on the identification of the systems possessing a confinement function, a confinement strategy has been proposed, in which DEMO confinement systems and barriers have been defined. In addition, confinement for the maintenance has been issued as well. The assignment of confinement barriers to the identified sources under abnormal and accidental conditions has been performed, and the DEMO main safety systems have been proposed as well. Finally, confinement related open issues have been pointed out, which need to be resolved in parallel with DEMO development. (paper)

[en] The growth of a oxide layer on lead was studied using the ESCA technique, where the 4f sub(5/2), sub(7/2 photoelectrons and M sub(4)N sub(67)N sub(67) and M sub(7)N sub(67)N sub(67) auger electrons were observed. Secondary electrons were analysed at 20 sup(0), 45 sup(0) and 75 sup(0) angles from the samples surface. Data at 20 sup(0) reveal more sensitivity to the chemical composition of the surface while at 75 sup(0) they have more sensitivity to the deep of the surface. As the auger electrons are most energetic than the photoelectrons, they are able to measure thicker layers. (author)

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