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Stabilization of cathode catalysts in hydrogen-fueled proton-exchange membrane fuel cells (PEMFCs) is paramount to their widespread commercialization. Targeting that aim, Pt-Au alloy catalysts with various compositions (Pt

We report on the growth of metal- and metal-oxide based nanoparticles (NPs) in heated polyol solutions. For this purpose, NPs are produced by the sputtering of a silver, gold, or a copper target to produce either silver, gold, or copper oxide NPs in pentaerythritol ethoxylate (PEEL) which has been annealed up to 200 °C. The objective of the annealing step is the fine modulation of their size. Thus, the evolution of the NP size and shape after thermal annealing is explained according to collision/coalescence kinetics and the affinity between the metal-/metal-oxide and PEEL molecule. Moreover, highlights of few phenomena arising from the annealing step are described such as (i) the reduction of copper oxide into copper by the polyol process and (ii) the effective formation of carbon dots after annealing at 200 °C.

Comprehensive understanding of the catalyst corrosion dynamics is a prerequisite for the development of an efficient cathode catalyst in proton-exchange membrane fuel cells. To reach this aim, the behavior of fuel cell catalysts must be investigated directly under reaction conditions. Herein, we applied a strategic combination of in situ/online techniques: in situ electrochemical atomic force microscopy, in situ grazing incidence small angle X-ray scattering, and electrochemical scanning flow cell with online detection by inductively coupled plasma mass spectrometry. This combination of techniques allows in-depth investigation of the potential-dependent surface restructuring of a PtNi model thin film catalyst during potentiodynamic cycling in an aqueous acidic electrolyte. The study reveals a clear correlation between the upper potential limit and structural behavior of the PtNi catalyst, namely, its dealloying and coarsening. The results show that at 0.6 and 1.0 VRHE upper potentials, the PtNi catalyst essentially preserves its structure during the entire cycling procedure. The crucial changes in the morphology of PtNi layers are found to occur at 1.3 and 1.5 VRHE cycling potentials. Strong dealloying at the early stage of cycling is substituted with strong coarsening of catalyst particles at the later stage. The coarsening at the later stage of cycling is assigned to the electrochemical Ostwald ripening process.

Formation of thin uranium hydrides films, UH2 and \b{eta}-UH3, synthesized by a reactive dc sputtering of uranium metal, was explored using variable deposition conditions. Obtained stable oxygen-free hydride films were studied by a variety of methods, both in situ (photoelectron spectroscopy - XPS), and ex-situ (x-ray diffraction - XRD, transmission electron microscopy - TEM), electrical resistivity, and magnetometry). Both types of hydrides are ferromagnetic, the Curie temperatures of UH2 and \b{eta}-UH3 are approx. 120 and 170 K, respectively. Ferromagnetism in the thin films is robust and does not depend on structure details while electrical resistivity data reflect disorder in both types of hydrides.

Platinum is the most widely used and best performing sole element for catalyzing the oxygen reduction reaction (ORR) in low-temperature fuel cells. Although recyclable, there is a need to reduce the amount used in current fuel cells for their extensive uptake in society. Alloying platinum with rare-earth elements such as yttrium can provide an increase in activity of more than seven times, reducing the amount of platinum and the total amount of catalyst material required for the ORR. As yttrium is easily oxidized, exposure of the Pt-Y catalyst layer to air causes the formation of an oxide layer that can be removed during acid treatment, leaving behind a highly active pure platinum overlayer. This paper presents an investigation of the overlayer composition and quality of Pt3Y films sputtered from an alloy target. The Pt3Y catalyst surface is investigated using synchrotron radiation X-ray photoelectron spectroscopy before and after acid treatment. A new substoichiometric oxide component is identified. The oxide layer extends into the alloy surface, and although it is not completely removed with acid treatment, the catalyst still achieves the expected high ORR activity. Other surface-sensitive techniques show that the sputtered films are smooth and bulk X-ray diffraction reveals many defects and high microstrain. Nevertheless, sputtered Pt3Y exhibits a very high activity regardless of the film's oxide content and imperfections, highlighting Pt3Y as a promising catalyst. The obtained results will help to support its integration into fuel cell systems.

Cerium dioxide is a scientifically and technologically important material with a wide range of potential applications, particularly in solid oxide fuel cells and catalysis. Herein, we report a study focusing on the synthesis of nanocrystalline cerium dioxide via thermal decomposition of the oxalate salt. Simply by changing reaction conditions (temperature, concentration, acidity, strike) during the precipitation of the cerium solution with oxalic acid, we were able to obtain different morphologies. The main reaction parameters were mapped and linked to the morphology of the final products. Additionally, it was proved that oxalate precipitation is a robust reaction proceeding at relatively extreme contitions. Moreover, the conversion of cerium oxalate to nanocrystalline oxide was followed to monitor the progress of the reaction, the texture evolution, and the grain growth. The results showed that, for unvaried heating cycle, the grain size of converted material is linked to morphology. The thinner was the original microcrystal the smaller were the CeO2 nanocrystals after calcination. In addition, the grains were found smaller near the edges of the ex-oxalate microcrystals. In both cases, this behavior results from asymmetrical limitations of diffusion during grain growth.

Biomedical Ti-6Al-7Nb alloy was prepared by a dedicated thermal treatment followed by equal-channel angular pressing (ECAP) and extrusion. Ultra-fine grained duplex microstructure consisting of deformed primary α-grains and fragmented α + β region was achieved. Microstructural changes during heating with the rate of 5 °C/min were studied by in-situ electrical resistance. Microstructure after deformation and also after subsequent heating was thoroughly characterized by scanning electron microscopy, X-ray diffraction, and positron annihilation spectroscopy (PAS). X-ray diffraction and positron annihilation spectroscopy proved a very high dislocation density and the presence of high concentration of vacancy clusters in deformed material. The ultra-fine grained microstructure of Ti-6Al-7Nb alloy is stable up to 440 °C, while upon heating to 550 °C and to 660 °C, the dislocation density decreases and vacancy clusters disappear. Enhanced microhardness can be achieved by ECAP followed by aging at 500 °C. Upon heating to 660 °C, the microhardness decreases due to ongoing recovery and recrystallization. Coincidence Doppler broadening (CDB), a special method of PAS, proved that dislocation cores are preferentially occupied by Al atoms that are known to cause substitutional solid solution strengthening.

Uranium Laves phase UTi2 does not exist in a pure form, but can be stabilised by the presence of hydrogen, which can be absorbed in concentration exceeding 5 H atoms/f.u. Low temperature specific heat, magnetic susceptibility, and resistivity indicate that UTi2H5 is a spin fluctuator close to the verge of magnetic ordering. Its susceptibility follows at high temperatures the Curie–Weiss law with U effective moment µeff[ = 3.1 µB/U and paramagnetic Curie temperature Θp = −200 K. The temperature dependence of specific heat exhibits a pronounced and weakly field dependent upturn in Cp/T versus T below 10 K reflecting the effect of spin fluctuations. It can be described by an additional T½ term. The Sommerfeld coefficient γ = 256 mJ/mol K2 classifies the compound as a mid-weight heavy fermion. Spin fluctuations are affecting also electrical and thermal transport and thermoelectric power, which all resemble UAl2. A lattice anomaly at ≈ 240 K, attributed to the melting of hydrogen sublattice, refl...

The 57Fe enriched almost single-phase perovskites Pb(Fe0.5Nb0.5)O3 (PFN) and Ba(Fe0.5Nb0.5)O3 (BFN), prepared by a ceramic method (solid-state synthesis), were studied by Mossbauer spectroscopy, nuclear magnetic resonance (NMR), conventional and synchrotron X-ray powder diffraction (XRD). The temperature dependences of hyperfine and structural parameters of PFN, BFN from 4.2 K to temperatures above ferroelectric ordering of PFN (TS ∼ 375 K), with attention to the values of magnetic and structural transitions, were obtained. The antiferromagnetic magnetic ordering transitions were found under the Neel temperatures TN ∼ 167(3) K and 32(2) K for PFN and BFN, respectively. The spin-glass transition was at TG ∼ 10(3) K and 20(5) K for PFN and BFN, respectively. In PFN sample a small change of structural parameters around TN and structural change from trigonal to cubic structure at T ∼ 400 K was observed by XRD. The temperature dependence of XRD shows stable cubic structure in the temperature range from 4.2 K to 530 K for BFN. From Mossbauer and NMR spectroscopies it is found that both structures have perturbed environments for Nb and Fe. However, in case of PFN the low values of transferred hyperfine fields disfavour random Fe/Nb arrangement and allow proposing a picture of Fe/Nb arrangement.

To obtain a material exhibiting magnetically induced reorientation (MIR), one of the magnetic shape memory effects, a well-developed method for single crystal growth is crucial. A [ 100 ] oriented Ni2MnGa single crystal exhibiting MIR was successfully prepared using the floating-zone technique with a high speed of 80 mm/h. The comparison with a sample grown by Bridgman method and a reference sample grown in AdaptaMat Ltd. by directional solidification is provided based on elemental homogeneity, crystallographic quality by x-ray diffraction, transformation behaviour and magnetic properties. All these methods indicated that the single crystal grown by floating zone with high speed is comparable or superior to the samples prepared by other methods. Importantly, the magnetization measurement revealed that the single crystal prepared this way exhibits MIR down to 10 K.

Crystalline materials with broken inversion symmetry can exhibit a spontaneous electric polarization, which originates from a microscopic electric dipole moment. Long-range polar or anti-polar order of such permanent dipoles gives rise to ferroelectricity or antiferroelectricity, respectively. However, the recently discovered antiferroelectrics of fluorite structure (HfO2 and ZrO2) are different: A non-polar phase transforms into a polar phase by spontaneous inversion symmetry breaking upon the application of an electric field. Here, we show that this structural transition in antiferroelectric ZrO2 gives rise to a negative capacitance, which is promising for overcoming the fundamental limits of energy efficiency in electronics. Our findings provide insight into the thermodynamically forbidden region of the antiferroelectric transition in ZrO2 and extend the concept of negative capacitance beyond ferroelectricity. This shows that negative capacitance is a more general phenomenon than previously thought and can be expected in a much broader range of materials exhibiting structural phase transitions.

Controlled synthesis of core@shell nanoparticles (NPs) for certain applications is a difficult challenge in many nanotechnology projects. In this report, a conventional arrangement composed of a gas aggregation source (GAS) is employed to generate the core NPs, which are subsequently coated by the shell materials in a secondary planar magnetron sputtering. The important difference to the usual system is the application of the two opposing planar magnetrons in a closed field configuration. The prepared core Ag NPs by a GAS are coated/treated by the two magnetrons with Ti targets. Our findings clearly show that the shell thickness can be controlled by tuning the power delivered to the secondary magnetron plasma. Characterizations of the prepared films, by x-ray diffraction technique, disclose multi-crystalline cores covered by amorphous shells. Based on x-ray photoelectron spectroscopy and energy dispersive x-ray spectroscopy measurements, different chemistry on the NPs surfaces and volume of the NPs can be achieved by tuning the operation conditions. Furthermore, the thermal annealing process leads to the growth of the crystallite size which results in emerging some microparticles caused by accelerating Ag surface mobility. The employed technique promises a reliable route to synthesize different heterogeneous NPs with stoichiometry tunable in a wide range for multi-functional devices.

Highly porous structures consisting of niobium nanoparticles (Nb NPs) are prepared using magnetron sputtering and inert gas aggregation method. Alongside the thermally-driven evolution of nanoparticle morphology, the microstructural genesis is probed in-situ by x-ray diffraction for the temperature range up to 800 °C. The as-deposited Nb NPs are formed by the Nb core and NbOx shell. The elevated temperature triggers the gradual oxidation that proceeds until 200 °C. Above this point the structure is fully amorphous. Further increase of the temperature to 450 °C leads to a transition to the crystalline TT-Nb2O5 phase, which hexagonal structure was solved in the current study. The subsequent rise of the temperature to 600 °C results in the conversion to the orthorhombic T-Nb2O5 phase. Up to this state, the size of nanoparticles corresponds to the size of crystallites. The annealing above 600 °C causes coalescence of NPs with the formation of hundreds-of-nanometers large structures.

Platinum is the most widely used and best performing sole element for catalyzing the oxygen reduction reaction (ORR) in low-temperature fuel cells. Although recyclable, there is a need to reduce the amount used in current fuel cells for their extensive uptake in society. Alloying platinum with rare-earth elements such as yttrium can provide an increase in activity of more than seven times, reducing the amount of platinum and the total amount of catalyst material required for the ORR. As yttrium is easily oxidized, exposure of the Pt-Y catalyst layer to air causes the formation of an oxide layer that can be removed during acid treatment, leaving behind a highly active pure platinum overlayer. This paper presents an investigation of the overlayer composition and quality of Pt

PtCu bimetallic alloys are known to provide better activity than pure platinum in proton exchange membrane fuel cells. However, such catalysts undergo complex degradation processes during fuel cell operation, resulting in deterioration of their activity. By using in situ electrochemical (EC) atomic force microscopy combined with in situ EC infrared reflection absorption spectroscopy, we provide a comprehensive investigation of morphological and structural transformations of PtCu model thin film catalysts during accelerated degradation tests (ADTs). The ADTs consist of potentiodynamic cycling to three different upper potentials relevant for different modes of fuel cell operation. The results show that, depending on the upper potential limit, PtCu alloy electrocatalysts are subject to drastic changes in the surface composition, morphology, and structure.

Ultra-nanocrystalline UH3-based ferromagnets with TC ≈ 200 K exhibit a flat temperature dependence of electrical resistivity with a negative slope both in the ferromagnetic and paramagnetic range. The ordered state with randomness on atomic scale, equivalent to a non-collinear ferromagnetism, can be affected by magnetic field, supressing the static magnetic disorder, which reduces the resistivity and removes the negative slope. It is deduced that the dynamic magnetic disorder in the paramagnetic state can be conceived as continuation of the static disorder in the ordered state. The experiments, performed for (UH3)0.78Mo0.12Ti0.10, demonstrate that the negative resistivity slope, observed for numerous U-based intermetallics in the paramagnetic state, can be due to the strong disorder effect on resistivity. The resulting weak localization, as a quantum interference effect which increases resistivity, is gradually suppressed by enhanced temperature, contributing by electron-phonon scattering, inelastic in nature and removing the quantum coherence.

We describe basic magnetic properties of uranium-based hydrides UTi2Hx, reported in literature as a cubic Laves phase, although the UTi2 binary phase does not exist. Using a high-temperature hydrogenation, we successfully synthesized two types of such hydrides, presumably with different H concentrations, one with a smaller lattice parameter a = 850.3 pm, which is a paramagnet close to the verge of magnetic ordering, the other with a = 858.8 pm, with a ferromagnetic ground state and ordering temperature TC = 54 K.

Colloidal solutions of metal nanoparticles (NPs) are typically produced by multi-step methods using a variety of chemicals. Resultant nanofluids require extra purification steps to remove the reactions by-products and modification steps to introduce anticoagulants for the solution stabilization. Here, we suggest a single-step method to produce nanofluid in which only two components are present: 22 nm-sized Cu NPs as a filler and polyethylene glycol (PEG, 400 g/mol) as a liquid base. The method employs magnetron sputtering to synthesize Cu NPs in a gas aggregation cluster source and their subsequent loading into vacuum-compatible PEG. The resultant nanofluid demonstrates strong plasmonic and photoluminescent activity, and shows enhanced stability over time, in contrast to conventional colloidal solutions. The approach offers an alternative for the production of nanofluids in which the processes of the NP formation are decoupled from the processes of their mixing with the liquid base.

A hardenable lightweight Mg-22 wt%Gd alloy with ultra fine grained (UFG) structure was prepared by high pressure torsion (HPT) at ambient temperature. The development of microstructure during HPT processing was investigated. A homogeneous UFG structure with grain size of 300 nm was achieved after 15 HPT revolutions. The UFG alloy exhibits enhanced strength due to work strengthening by tangled dislocations forming a dense forest throughout grains. Dislocation density in the sample was determined by positron annihilation spectroscopy (PAS) and X-ray line profile analysis (XLPA). It was found that there is an additional source of X-ray profile broadening in addition to small crystallites and micro-strains caused by dislocations. The additional micro-strain component was attributed to lattice modulation by Gd-rich nano-wires formed by agglomeration of Gd solutes and to strains arising from boundaries of crystallite domains and inter-domain interactions. Analysis of the influence of the crystallite size on the strength of UFG Mg-22 wt%Gd alloy revealed a breakdown in the Hall-Petch relationship when the crystallite size decreased below a critical value of ≈30 nm.

As-deposited Pt-Ni and annealed Pt-Ni alloy catalyst films prepared by magnetron co-sputtering were investigated in order to quantify their ageing during accelerated durability test. The parameters of the durability test were chosen to simulate severe potential conditions that may occur at start-up/shut-down cycles of a fuel cell. Using in situ electrochemical atomic force microscopy complemented with ex situ energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, synchrotron radiation photoelectron spectroscopy and X-ray diffraction provided step-by-step correlation of chemical and morphology changes induced by catalyst’s aging processes. We show that the as-deposited Pt-Ni films face severe chemical stability problem which leads to almost complete destruction of the alloy during the durability test. On the other hand Pt-Ni films annealed in vacuum are more resistive to morphological and chemical changes. It was confirmed that upon annealing due to redistribution of Pt and Ni atoms Pt-skin is formed on catalyst surface, which is responsible for a better stability during the aging test.

Corrosion of alumina-based metal melt filters functionalized by 3Al2O3·2SiO2 or fused SiO2 was investigated using local chemical and microstructure analyses and thermodynamic calculations. Molten aluminium alloy AlSi7Mg0.6 was employed as corrosion medium. The aluminium alloy was melted in a Spark Plasma Sintering apparatus in order to avoid the melt flow. During the reaction with the AlSi7Mg0.6 melt, 3Al2O3·2SiO2 partly decomposed, and Al2O3 reacted with magnesium from the melt and with oxygen from SiO2 to MgAl2O4. Silicon precipitated in the aluminium alloy. For corundum functionalized by fused SiO2, metastable γ-Al2O3 was detected additionally to the above phases for short reaction times.

A new type of uranium binary hydride, UH

Hydrogenation effects on the crystal structures and magnetic properties of Tb2Co2Ga, Tb2Ni2Ga, and Tb3Co3Ga were studied. Tb2Co2Ga, Tb2Ni2Ga (both structure type W2CoB2), and Tb3Co3Ga (structure type W3CoB3) are structurally related belonging to inhomogeneous linear structure series based on the TlI- (also referred to as CrB type) and YAlGe- (ordered derivative of the binary type UPt2) type structure motives. The hydrides Tb2Co2GaH6.2, Tb3Co3GaH9.7, and Tb2Ni2GaH5.1 were synthesized at room temperature with hydrogen pressures of 52–53 ​kPa. Hydrogenation results in strongly anisotropic lattice volume expansion ΔV/V ​= ​19.2–20.0%. It also leads to a decrease of the Curie temperature in ferromagnetic Tb2Co2Ga and Tb3Co3Ga and practically suppresses the antiferromagnetic ordering in Tb2Ni2Ga. A model of the crystal structure of the hydride Tb3Co3GaH10 with four hydrogen positions was suggested based on stronger effect of hydrogenation on the TlI-type slabs. The more complex character of the magnetic phase transitions for Tb2Co2Ga and Tb3Co3Ga presumes involvement of Co in the magnetism of these compounds, while Tb2Ni2Ga acts as a typical 4f-electron system with dominating RKKY exchange interactions.

U-V alloys with variable phase composition were prepared using ultrafast cooling. 15 at.% V is not sufficient to suppress entirely the orthorhombic α-U type of phase and higher alloying concentrations lead to a segregation of pure vanadium. The alloys are stable with respect to H2 exposure at pressures of 105 Pa. Nevertheless hydrogenation proceeds slowly at high H2 pressures. Resulting hydrides exhibit a common β-UH3 structure. This is unusual among the U-T systems, which yield either α-UH3 or nanocrystalline β-UH3 structures. The UH3-V system is ferromagnetic with the Curie temperatures monotonously increasing with the V concentration to TC = 190 K for 15 at.% V. Magnetic moments remain on the level of 1.0 μB/U. The results prove that the increase of TC in alloyed U hydrides of the UH3-T type does not depend on particular structure details or type of the T element, although the latter modifies somewhat the maximum TC values achieved. The situation can be understood assuming that the substitution of U by T provides an enhanced H/U ratio, while the U-H interaction is a prominent element of the 5f moments formation and ordering.

A series of single crystal Ni2MnGa1-xInx samples, varying in compositions between x = 0 to 0.15, were grown by Bridgman method. Critical temperatures were obtained from the magnetisation and electrical resistivity measurements. A Curie temperature and the temperatures of pre-martensitic and martensitic transformation decrease with increasing indium content. The decrease rate is faster than the rate published previously on polycrystalline samples, since no martensitic transformation was observed in our samples with the indium content x > 0.05. The results of X-ray diffraction measurements of low temperature martensitic phase show significant decrease of monoclinic lattice parameter a and increase of monoclinic lattice parameter c and γ angle with respect to increasing indium content. Composition dependence was observed also for the modulation vector in martensitic and pre-martensitic phase, where its x and y coordinates gain values around 3/7 and 1/3 respectively.

Crystal structure, magnetic and electrical properties of thin U–Mo films and their hydrides prepared by reactive sputter deposition from metallic targets were studied. The films are metallic but with high values of electrical resistivity. Both bcc U0.79Mo0.21 thin film and the hydride (UH3)0.74Mo0.26 (β-UH3 structure type) have a very strong texture. Superconductivity is identified below Tc = 0.55 K for U0.79Mo0.21. The critical field of 1.0 T is exceeding that of α-U (0.3 T). The hydride film (UH3)0.74Mo0.26 is a ferromagnet with the Curie temperature TC = 165 K, higher concentration of Mo somewhat reduces the TC value. Deposition on a cooled substrate reduces the grain size of the hydride, approaching the limit of amorphous state. The U–Mo films and hydrides exhibit the net negative temperature coefficient of resistivity, TCR = dρ/dT, attributed to the randomness on atomic scale, yielding very strong scattering of electrons and weak localization.

Thin films of SrAl 12 O 19 were prepared on α-Al 2 O 3 (0001) substrates through the chemical solution deposition method and thermal treatment. Two types of precursor systems were used: stoichiometric mixture of strontium methoxyethoxide with aluminium iso-butoxide, and strontium methoxyethoxide topotactically reacting with Al 2 O 3 substrate. Two distinctly different film-substrate orientation relationships were observed. In the latter case the orientation can described as perfect hexagon-on-hexagon epitaxy with 11 2 − 0 SrAl12O19 || 10 1 − 0 Al2O3 and (0001) Al2O3 || (0001) SrAl12O19 . This relationship has 1.17% lattice misfit in the substrate plane. In the former case SrAl 12 O 19 grains are rotated about the substrate normal and form more orientation variants that can be explained by the coincident-site lattice model for grain boundaries. We demonstrated that both types of SrAl 12 O 19 films can be used as a chemical buffer and structural template layer for the growth of oriented hexagonal ferrite thin films. In both types of films the (BaSr)Fe 12 O 19 phase cope the in-plane orientation of their respective templates.

Thin films of Ba2Zn2Fe12O22 (Y-type) ferrite were prepared through the chemical solution deposition method using SrTiO3(111) substrates covered with magnetoplumbite (M-Type) seed layer. Seven M phases with different chemical composition, magnetic character and lattice misfit values were investigated in their use as template and buffer layers. AFM, X-ray and electron back-scatter diffraction measurements of specimens with lattice mismatches ranging from −0.8% to −7.0% revealed increasing in-plane misalignment with increasing lattice misfits. X ray texture analysis together with magnetization measurements demonstrated c-oriented growth of Y films that copes the in-plane orientation of their respective M-type templates. The best in-plane alignment of Y film was obtained when M phases with lattice misfits of −4.9% and −1.5% relative to substrate and Y films, respectively, were used. The effect of surface microstructure of seed layer on oriented growth of Y films was discussed in terms of surface coverage and surface topography.

Successive crystallization of amorphous Cr-Zr-O thin films, formation of the (Cr,Zr)2O3/(Zr,Cr)O2 nanocomposites and the thermally induced changes in the hexagonal crystal structure of metastable (Cr,Zr)2O3 were investigated by means of in situ high-temperature synchrotron diffraction experiments up to 1100 °C. The thin films were deposited at room temperature by using reactive ion beam sputtering, and contained 3–15 at.% Zr. At low Zr concentrations, chromium-rich (Cr,Zr)2O3 crystallized first, while the crystallization of zirconium-rich (Zr,Cr)O2 was retarded. Increasing amount of zirconium shifted the onset of crystallization in both phases to higher temperatures. For 3 at.% of zirconium in amorphous Cr-Zr-O, (Cr,Zr)2O3 crystallized at 600 °C. At 8 at.% Zr in the films, the crystallization of (Cr,Zr)2O3 started at 700 °C. At 15 at.% Zr, the Cr-Zr-O films remained amorphous up to the annealing temperature of 1000 °C. Metastable hexagonal (Cr,Zr)2O3 accommodated up to ~ 3 at.% Zr. Excess of zirconium formed tetragonal zirconia, which was stabilized by chromium.

Several diverse types of UH3-based hydrides can be prepared by hydrogenation of bcc U-based alloys. Pair Distribution Function (PDF) analysis using high-energy X-rays identified that the (UH3)1-x Mo x hydrides are nanocrystalline, with the structure motif based mainly on the β-UH3 structure. α-UH3 represents a minority component. On the other hand, PDF of the (UH3)1-x Zr x hydrides corresponds well to the α-UH3 crystal structure. All the hydrides are ferromagnetic, with the Curie temperature T C reaching up to 203 K.

International audience; The corrosion behaviour of Mg-0.3Ce, Mg-0.41Dy, Mg-0.63Gd, Mg-1.44Nd and Mg-1.43La (wt.%) alloys in 3.5 wt% NaCl solution was investigated using electrochemical tests. The as-cast microstructures of the Mg-RE alloys were characterized by the presence of second phases (Mg x Ce, Mg 41 Dy 5 , Mg 12 Gd, Mg 12 Nd, Mg 41 Nd 5 , Mg 24 Nd and Mg 12 La) with different volume fraction and distribution. Results show that the corrosion mechanism was altered from uniform to localized corrosion mechanism depending on the specific RE alloying elements. The corrosion resistance of the Mg-RE alloys is increasing in the following order: Mg-1.43La, Mg-1.44Nd, Mg-0.3Ce, Mg-0.63Gd and Mg-0.41Dy. Accordingly, the corrosion morphology in the best resistant Mg-0.41Dy alloy and the worst Mg-1.43La alloy were observed and compared after 2h and 24 h of immersion using SEM-EDS, XPS and XRD analysis. The formation of the Dy 2 O 3 oxide prevents the Mg-0.41Dy alloy from pitting corrosion and lead to an excellent corrosion surface even after 24 h of immersion. Meanwhile, the presence of a high fraction of the Mg 12 La phase along the grains boundaries in the Mg-1.43La alloy causes severe pitting corrosion by acting as anodic phase.

Byly zkoumány interakce mezi polyolefiny a křemíkovými substráty při depozici z plynné fáze ve vakuu. Simulace pomocí molekulární dynamiky ukázaly, že polyolefiny se po adsorpci rozbalí, a že dvě makromolekuly stačí pro vytvoření stabilního zárodku. AFM měření se superostrým hrotem ukázala formování 3,5 nm velkých globulárních klastrů, které se dále transformovaly do 2D ostrůvků. Ostrůvky rostly horizontálně prostřednictvím přidávání nových molekul na jejich okraj při zachování tloušťky. Vývoj velikosti ostrůvků byl charakterizován prostřednictvím diagramu zóny záchytu s využitím generalizovaného Wignerova škálování. Zjištěná kritická velikost ostrůvků byla 1, v souladu se simulacemi pomocí molekulární dynamiky. Delší doby depozice vedly ke srůstání ostrůvků a vyhlazování jejich povrchu s růstovým exponentem γ = –0,33 a dynamickým exponentem 1/z = –0,21. Vyhlazování je doprovázeno krystalizací vedoucí k vytvoření ortorombických polyolefinových krystalů detekovaných pomocí XRD. Interactions between polyolefins and silicon substrates are investigated upon their physical vapor deposition under vacuum. Molecular dynamics simulations show that polyolefins unfold upon adsorption and that two macromolecules suffice to produce a stable nucleus. Supersharp probe AFM measurements reveal the formation of 3.5 nm globular clusters that further transform into two-dimensional islands. The islands grow via attachment-limited aggregation by accepting new molecules from the edge, keeping the thickness constant and expanding laterally. The evolution of the island growth is analyzed within the framework of capture zone distribution analysis using generalized Wigner scaling. The critical island size is found to be 1, confirming the results of molecular dynamics simulations. Upon longer deposition times, the islands coalesce, whereas their surface smoothens with a growth exponent of γ = –0.33 and a dynamic exponent of 1/z = –0.21. Smoothening is accompanied by crystallization phenomena that result in the formation of orthorhombic polyolefin crystals, as detected by XRD.