[en] A modification is described of the singluar value decomposition (SVD) method suitable for underdetermined linear least squares (LLS). When a set of data to be fitted is incomplete and does not allow an independent determination of all model parameters, the modified method automatically merges a previously available approximate solution into the LLS results. The solution so produced is more appropriate to the particular problem than the usual SVD solution, while still being a LLS estimate of the whole set of parameters. The method is discussed with reference to the LLS determination of unit-cell dimensions during the step-by-step assignment of h, k, l indices of a diffraction pattern. (orig.)

[en] Zinc oxide nanoarchitectures may be employed as binder-free, high specific capacity anodes for lithium batteries. By means of simple and low-impact wet chemistry approaches, we synthesized 1D (nanorods), 2D (single- and multi-layered nanosheets), and 3D (nanobrushes) ZnO arrays. These nanoarchitectures were compared as far as concerns their electrochemical properties and the structural modifications upon lithiation/delithiation. The best results were offered by 2D nanosheets, which showed reversible capacity of the order of 400 mAhg⁻¹ after 100 cycles at 1 Ag⁻¹. This was due to: i) small nanoparticles, with average diameter of about 10 nm, which maximize the array specific surface area and favor the formation of the LiZn alloy; ii) the presence of a mesoporous texture, which allows larger space for accommodating the volume changes upon lithiation/delithiation. However, also these 2D structures showed large irreversible capacity losses. Our work highlights the need for more efficient buffering solutions in ZnO binder-free nanostructured anodes. - Graphical abstract: ZnO nanosheets as anode materials for lithium batteries.

[en] SHS experiments have been performed starting from the elemental compositions corresponding to all the Zr-Si intermetallic compounds. Analysis of the products shows that the Si rich compositions give, as the major product components, ZrSi₂ and ZrSi, and the Zr rich composition the high temperature phase Zr₅Si₃. Melting of silicon has been identified as the triggering step for the combustion process. Once initiated the reaction involves solid (Zr)-liquid (Si) or liquid-liquid interactions. The phase formation is then controlled by kinetic parameters rather than thermodynamic ones. Solid-solid interaction can play an important role in the pre- and post-front regions; these have been studied through diffusion couples experiments. (orig.)

[en] This work deals with the synthesis and Rietveld structure refinement of a zirconium-praseodymium yellow pigment prepared either by a traditional ceramic process route and by an unconventional synthesis method based on SHS (self-propagating high-temperature synthesis). In order to confirm the effective formation of the solid solutions, SEM imaging and EDS analysis, and leaching tests have also been performed. The results proved the applicability of the unconventional processing route for obtaining yellow solid solutions. (orig.)

[en] The interest in ⁸⁹Zr radioisotopes is increasing in the last years due to its half-life that allows to label biomolecules, such as monoclonal antibodies, for pharmacokinetic studies and clinical trials to trace slow biological process. Due to the availability of the target material in natural form, the ⁸⁹Y(p,n)⁸⁹Zr is considered the best nuclear reaction for the production of ⁸⁹Zr in medical cyclotrons. Nowadays, the design and manufacturing of appropriate cyclotron solid targets for the production of large amounts of ⁸⁹Zr with high specific activity remain a technological challenge. The LNL-INFN group, in the framework of the LARAMED (laboratories for radioisotopes of medical interest) project, has developed two methods for ⁸⁹Y targets realization for the production of ⁸⁹Zr. The targets have been tested in collaboration with IRCCS Sacro Cuore-Don Calabria Hospital in Negrar (VR). The first proposed method is Magnetron Sputtering (MS) deposition of yttrium material directly onto niobium backing (chosen due to its chemical inertness). MS is a physical vapour deposition technique that takes place in a vacuum by means of inert gas plasma (Ar). The material of interest is attached to the cathode, and plasma is created when a difference of potential is applied between the cathode and the substrate (anode). The positive ions of the inert gas are accelerated towards the cathode. When the ions collide with the atoms of the sputtering target, the energy transfer causes the detachment of some atoms, which are then deposited on the substrate. Magnetron sputtering is characterized by elevated plasma utilization efficiency thanks to its magnetic confinement.

[en] The combustion syntheses of all the intermetallic compounds in the Zr-Al binary system have been investigated. Analyses of the reaction products show that for compositions of the reacting mixture richer than 60 at.% in Al the products always contain a mixture of ZrAl₃, ZrAl₂ and Zr₂Al₃ in different proportions. Zr-rich samples always produce a mixture of Zr₅Al₃, Zr₃Al₂, ZrAl₂ and Zr₂Al₃. DTA investigations have shown that the exothermic process responsible for the front propagation is represented, for all starting compositions, by the reaction of molten aluminum with solid zirconium to form ZrAl₃. When fine powdered reactants are used, solid-state interaction also contributes to the reaction ignition. (orig.)

[en] The dissolution kinetics of nickel in liquid aluminum at temperatures in the range 767-867 deg. C were investigated under the influence of a DC current. The current had a marked effect on the dissolution rate constant. Correspondingly, the application of the current significantly decreased the activation energy of dissolution. The direction of the DC current was shown to have an effect on dissolution. When the electronic flow was in the direction of dissolution, a further increase in dissolution was observed and attributed to electromigration. Calculations of the effective diffusion coefficient, D_eff, of Ni through one of the two intermetallic layers, Al₃Ni₂, were made for different current densities and temperatures. From measured electromigration enhanced flux, the effective charge, z*, on the diffusing Ni was calculated

[en] The homogeneity range of Bi-Sr-Ca-Cu oxides with two-layers (''2212'') structure has been investigated with X-ray powder diffraction and electron microprobe determination on materials with nominal Bi₂Sr_3-xCa_xCu₂O_8+y (x = 1/2 in 0.1 steps) composition and being prepared at two different oxygen partial pressures. The results show Bi over-stoichiometry and a wide range of Sr/Ca substitution. DC resistivity measurements indicate that the hole concentration is controlled by both oxygen non-stoichiometry and cation molecularity. It is shown that a single phenomenological relation between hole concentration and electrical properties can explain in a consistent way the complex behaviour of the whole set of materials with different oxygen non-stoichiometry and cation molecularity. (orig.)

[en] The paper describes the preparation of micropatterned zinc oxide films through a synthetic route based on the thermal degradation of metal-loaded poly(ethylene glycol)-based hydrogels. This approach requires very simple apparatuses and involves only simple, inexpensive and environmentally friendly chemicals. Highly transparent and crack free nanocrystalline films were obtained through this route. The evolution of the films during the thermal degradation and the influence of synthesis parameters on the film characteristics were investigated by thermal analysis, X-ray grazing incidence diffraction, scanning electron microscopy, atomic force microscopy and micro-Raman. The response toward reducing gasses was tested at different temperatures. Finally, the micropatterning of ZnO films through soft lithography has been characterized.

[en] Highlights: • A hybrid electrolyte membrane for LiB based on nanostructured YSZ was sintered HP-FAST. • The nano-porosity was retained and the membrane activated with a standard LiPF₆-EC-DMC solution. • The liquid is nano-confined in the ceramic membrane. • Excellent resistance to dendrite formation for more than 350 cycles in a Li/electrolyte/Li symmetrical cell. • The nano-porous ceramic hybrid electrolytes may be conveniently used in LMB. -- Abstract: The use of lithium metal as the anode for Lithium Metal Batteries (LMB) requires having solid or quasi-solid electrolytes able to block dendrites formation during cell cycling. Here we reported on a hybrid electrolyte membrane based on nanostructured yttria-stabilized-zirconia, sintered by means of High Pressure-Field Assisted Sintering Technique (HP-FAST) in order to retain proper nano-porosity, and activated with a standard LiPF₆-EC-DMC solution. By a thorough physico-chemical and functional characterization, we demonstrated that the liquid is effectively nano-confined in the ceramic membrane, and the resulting quasi-solid electrolyte is non-flammable. A remarkable conductivity value of 0.91 mS cm⁻¹ was observed at room temperature, with activation energy of 0.2 eV, and cation transference number, t⁺ = 0.55, substantially higher than that of the pure liquid electrolyte. The hybrid electrolyte showed electrochemical stability up to 5.5 V vs. Li⁺/Li, and excellent resistance to dendrite formation for more than 350 cycles in a Li/electrolyte/Li symmetrical cell. A full cell Li/electrolyte/LiMn₂O₄ showed more than 90 mAh g⁻¹ at 2C for more than 120 cycles. These very promising results indicated that nano-porous ceramic hybrid electrolytes may be conveniently used in LMB.