No abstract available

[en] The present work was aimed at determining the potential of the transition Fm²⁺ = Fm³⁺ + e, assuming that it was close to the potential of ytterbium reduction from trivalent to divalent state. For this purpose use was made of a cocrystallization technique of divalent fermium with strontium chloride from ethanol solutions in the presence of divalent ytterbium as a reducer. The ionic radii of divalent fermium and strontium being very close, cocrystallization of fermium with strontium chloride will proceed by the isomorphism or isodimorphism similar with cocrystallization of divalent fermium with samarium dichloride precipitate. The theory and experimental details are presented and results are discussed. (U.K.)

No abstract available

[en] The report of a stable, monovalent, cesium-like ion of mendelevium is in conflict with recent estimates of the relative stability of Md⁺, based on electrochemical systematics of the actinide series. To clarify this situation, experiments using controlled-potential electrolysis were undertaken to study the over-all reduction mechanism of Md³⁺ to the amalgam. Half-wave amalgamation potentials were measured by radiocoulometry in the presence of weak (acetate) and strong (citrate) complexing agents. The half-wave potentials with respect to the normal hydrogen electrode were found to be -1.49 +- 0.01 V in acetate and -1.60 +- 0.01 V in citrate solutions. The results showed that Md behaved analogously to Fm, which has been shown to undergo electrode reduction in two steps, 3+ → 2+ and 2+ → 0. The half-wave potentials observed for Md are believed to be characteristic of the reduction 2+ → 0. Further, the shift in the half-wave potential of mendelevium caused by a strong complexing agent is too large to be explained by reduction of a cesium-like, monovalent ion. (author)

[en] Cocrystallization of Fmsup(2+) and Md⁺ with NaCl and KCl in aqueous-ethanol solutions in the presence of bivalent lanthanides is investigated. On the basis of thermodynamic study of the cocrystallization results it has been ascertained, that at the redox potential of Eusup(2+) mendelevium is reduced to oxidation state 1+ and it is cocrystallized with KCl and NaCl due to isomorphous cocrystallization. Fermium in the same medium is reduced by Smsup(2+) only to the oxidation state 2+ and forms anomalously mixed crystals (AMC) withKCl,at that, its cocrystallization coefficient increases linearly with Cl^- concentration increase inagreement with calculation. The dependences established show, that Md*H+ and Fmsup(2+) do not form stable chloride complexes and in this respect they are analogs of alkali and alkaline earth ions. The study of Md⁺ withSmF₂ and YbF₂ cocrystallization has shown, that in the systems AMC are formed in a similar way toAg⁺ cocrystallization with SrF₂

[en] The experimental data obtained from radiopolarographic and radiocoulometric measurements on transplutonium elements Am, Cm, Bk, Cf, Es and Fm permitted to explore the oxidation-reduction behavior of these elements in aqueous media. Mechanisms and kinetics of the electrochemical reduction to the metallic state at a mercury cathode have been stated. Am, Cm, Bk, Cf and Es are amalgamated according to M³⁺ + 3e + Hg reversible M(Hg) mechanism whereas M²⁺ + 2e + Hg reversible M(Hg) mechanism is observed for Fm. The reduction processes are reversible for Cf, Es and Fm. The determination of reversible half-wave potential for Cf, Es and Fm permitted to estimate the formal E⁰M³⁺/M⁰ potentials which are unmeasurable by classical methods

[en] Coupling of spins and phonons in ferromagnets (FM) may persist up to mm length scale, thus generating macroscopic spatially distributed spin accumulation along the direction of an applied thermal gradient to an FM slab. This typical feature of transverse spin Seebeck effect (TSSE) has been demonstrated so far using electrical detection methods in FM films, in particular in a patterned structure, in which FM stripes grown onto a substrate perpendicular to the applied thermal gradient direction are electrically and magnetically isolated. Here we report optically detected TSSE response in isolated FM stripes based on permalloy deposited on SiN substrate, upon the application of a thermal gradient. For these measurements we used the magneto-optic Kerr effect measured by an ultrasensitive Sagnac interferometer microscope that is immune to thermo-electrics artefacts. We found that the optical TSSE coefficient in the NiFe stripes geometry is about one order of magnitude smaller than that in the continuous NiFe film, which is due to the limited phonons path in the FM stripes along the thermal gradient direction. Our results further confirm the existence of TSSE response in conducting FM compounds. (paper)

[en] Cocrystallization experiments reported previously indicated a monovalent state existed for Md. Some of these experiments were repeated recently and a series of new ones was performed in which an attempt was made to prepare Md(I) by reduction with Sm²⁺ in an ethanolic or fused KCl medium. The oxidation state of Md was determined by the amount of ²⁵⁶Md tracer (>= 10⁵ atoms) carried on precipitates of SmF₂/SmF₃, SmCl₂, RbCl and Rb₂PtCl₆. Comparisons of the coprecipitation behavior of Md with the behavior of tracer amounts of the elements Es, Fm, Eu, Sr, Y and Cs showed that Md consistently follows the behavior of Fm²⁺, Eu²⁺ and Sr²⁺, rather than the behavior of Cs⁺. Therefore, it is concluded that Md cannot be reduced to a monovalent oxidation state with Sm²⁺ and that the earlier claim for Md(I) is unsubstantiated. (author)

[en] Tm²⁺, Es²⁺, Cf²⁺, Am²⁺, Eu²⁺, Sr²⁺, Cs⁺ cocrystallization with KBr in hexamethylphosphorus-triamide (HMPA) with different concentration of ion bromide has been studied. Divalent lanthanoids (Ln²⁺) and actinides (An²⁺) in this solvent are shown not to cocrystallize with halides of alkaline metals unlike aqueous-ethanol solutions, where An²⁺ capture by a solid phase is observed, whereas Ln²⁺ cocrystallization doesn't occur. Difference in behaviour of these elements in HNPA and C₂H₅OH is explained by different solvating capability of these solvents

[en] Cocrystallization of Cf²⁺, Es²⁺, Tm²⁺ and divalent lanthanides (Yb, Eu, Sm) with SrI₂x18 crown-6 in THF medium with Tm²⁺ oxidation potential has been studied. All investigated elements are shown to cocrystalize with a solid phase due to formation of actual solid solutions. Values of their cocrystallization coefficients are close to 1 and don't depend on concentration of ion iodide. The conclusion is made that in THF solutions actinide diiodides as well as lanthanide diiodides and SrI₂ are dissociated completely