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The magnetic and structural properties of [Fe.sub.53] [Pt.sub.47] deposited by alternated-layer sputtering on MgO (100), heated at temperatures up to T = 550 [degrees]C, were investigated. The effect of a subsequent thermal annealing performed at the same temperature was found to be essential for obtaining 10-nm FePt thin films with a high degree of ordering and high squareness. Index Terms--FePt L[1.sub.0], perpendicular recording media, permanent magnets, thin films.

We report on the optical characterization of TeO[sub 2] amorphous films deposited by radio-frequency (rf) reactive sputtering. X-ray diffraction, electronic microscopy, and Rutherford backscattering analysis have been performed in order to assess the structural and compositional properties of the samples. The linear optical characterization has been performed by variable angle spectroscopic ellipsometry at wavelengths between 260 and 1700 nm, leading to determination of the dispersion of the complex refractive index for sputtered tellurium dioxide. In the spectral range of transparency, between 1700 and 500 nm, refractive index values ranging from 2.05 to 2.16 have been obtained. The dispersion of the complex third-order nonlinear optical coefficient of the sample has been evaluated in the near-infrared spectral range by third harmonic generation measurements. The out-of-resonance value of the Χ[sup (3)] coefficient for TeO[sub 2] is in the range between 1.2 × 10[sup -12] and 1.4 × 10[sup -12] esu. The conjugation of optical transparency, high nonlinear refractive index and the possibility of growing films of good optical quality, make rf sputtered TeO[sub 2] a promising material for the implementation of devices for the processing of optical communication signals. [ABSTRACT FROM AUTHOR]

A set of modular components is designed, prepared and combined to produce an innovative method for the self-assembly of large supramolecular structures on silicon wafers. The complete orthogonality of the two interactions has allowed the molecular level control of each step of the solid-state assembly and the response to precise external stimuli.

The production and optical characterization of samples of stoichiometric TeO2 glass thin films, grown by reactive sputtering from Te targets are discussed. The analysis has proved to suitable to realize films of good optical quality in the micrometer thickness range.

Ceria was deposited onto boron doped polycrystalline diamond (BDD) cathodes, through electrochemically induced precipitation from nitrate-based solutions. The deposits were characterized using SEM-EDS, HRTEM, XRD and XPS. The morphology, thickness and composition of ceria films, which besides CeO2 contained Ce(OH)3 when prepared at very negative potential, were controlled by tuning the deposition parameters. Thin Ce(OH)3-free ceria films allowed CO2 electrochemical reduction at overpotentials below 50 mV, yielding formic acid with faradaic yield higher than 40% and stable performance for many hours. Ceria seemed to act as a co-catalyst that activated CO2 for reduction at the H-terminated BDD surface, because comparable results were not obtained with ceria-coated glassy carbon electrodes. [ABSTRACT FROM AUTHOR]

Electrocatalytic oxygen reduction (ORR) is an emerging synthetic strategy to prepare H2O2 in a sustainable fashion. N‐doped graphitic carbon with embedded cobalt nanoparticles was selected as an advanced material able to selectively trigger the ORR to form H2O2 with a faradaic efficiency of almost 100 % at very positive applied potentials. The production of H2O2 proceeded with high rates as calculated by bulk electrolysis (49 mmol g−1 h−1) and excellent current densities (≈−0.8 mA cm−2 at 0.5 V vs. reversible hydrogen electrode). The totally selective behavior depended on the combination of concomitant material features, such as the textural properties, the nature of the metal, the distribution of N moieties, the acidic environment, and the applied potential. [ABSTRACT FROM AUTHOR]

Topological insulator (TI) properties of granular Sb2Te3 thin films, grown by MOCVD at room temperature on 4″ SiO2/Si substrates, are investigated. The negative magneto‐conductance (MC), analyzed in terms of the Hikami–Larkin–Nagaoka theory, reveals the presence of a clear weak antilocalization (WAL) effect, thus demonstrating the TI character of our system. The extracted WAL prefactor (α) values are explained in terms of the film conductance, in agreement with the existing models for WAL in transport disordered systems. The dephasing length ( l ϕ) dependence on temperature is affected by the grain size of the film and might in turn explain the observed temperature dependence of α and of the conductance. These results demonstrate the feasibility of technologically‐relevant processes to synthesize TIs films, at the same time providing a tool to investigate the effects of the film microstructure on the topological character of their transport properties. [ABSTRACT FROM AUTHOR]

We report the structural and magnetic properties of chemically synthesized dual-phase Co2NiGa shape memory Heusler nanoparticles (NPs). Rietveld analysis of the X-ray diffraction (XRD) data reveals a dual-phase structure for all studied Co2NiGa NPs: the B2 ordered cubic austenite (β) and the tetragonal (γ or martensite β′) phases. We find that the fraction of the tetragonal γ-phase and magnetic properties of NPs consisting of β + γ phases prepared using a heating rate of 0.5 K min−1 can be tuned by varying the Ni-content. Higher saturation magnetization and Curie temperature are observed for Co2NiGa NPs with a higher fraction of the γ-phase. Dual-phase β + γ Co2NiGa NPs exhibit the highest Curie temperature (1153 K) of all known Heusler NPs. Furthermore, the martensite β′-phase is found to coexist with the β-phase for NPs synthesized using a higher heating rate of 2 K min−1. Co2NiGa NPs of mixed β + β′ phase are paramagnetic at room temperature and exhibit low magnetization due to the presence of the martensite phase. High temperature XRD measurements of Co2NiGa NPs with β + β′ phases confirm their irreversible phase transition of the β-phase starting at a temperature of 837 K and the structural stability of the tetragonal β′-phase. The developed new synthetic method makes it possible to fabricate Co2NiGa NPs with structure and properties tailored for high temperature magnetic shape memory devices at the nanoscale. [ABSTRACT FROM AUTHOR]

Energy-loss magnetic chiral dichroism (EMCD) is a versatile method for measuring magnetism down to the atomic scale in transmission electron microscopy (TEM). As the magnetic signal is encoded in the phase of the electron wave, any process distorting this characteristic phase is detrimental for EMCD. For example, elastic scattering gives rise to a complex thickness dependence of the signal. Since the details of elastic scattering depend on the electron's energy, EMCD strongly depends on the acceleration voltage. Here, we quantitatively investigate this dependence in detail, using a combination of theory, numerical simulations, and experimental data. Our formulas enable scientists to optimize the acceleration voltage when performing EMCD experiments. [ABSTRACT FROM AUTHOR]

Organo-halide perovskite solar cells (PSCs) have emerged as next-generation photovoltaics, owing to their high power-conversion efficiency (PCE), lower production cost, and high flexibility. ABX3-structured methylammonium lead triiodide (CH3NH3PbI3 or MAPbI3) perovskite is a widely studied light-absorbing material in PSCs. Interestingly, a small amount of chlorine incorporation into MAPbI3 increases charge carrier diffusion lengths (from 129 nm to 1069 nm), which enables planar structured PSCs with high PCEs. However, existence of chloride ions in the final perovskite film is still under debate. Contrastingly, few studies reported a negligible amount or absence of chloride ions in the final film, while others reported detection of chloride ions in the final film. Herein, we observed the microstructure and chlorine content of MAPbI3−xClx thin films with increasing temperature via an in-situ nano-Auger spectroscopy and in-situ scanning electron microscopic analysis. The relative precipitation of MAPbI3−xClx films occur at lower temperature and MAPbI3−xClx grains grow faster than those of MAPbI3 grains. Local concentrations of chlorine at intragrain and the vicinity of grain boundary were analyzed to understand the behavior and role of the chloride ions during the microstructural evolution of the MAPbI3−xClx films. [ABSTRACT FROM AUTHOR]

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010. [ABSTRACT FROM PUBLISHER]

Antimony telluride (Sb 2 Te 3 ) thin films were prepared by a room temperature Metal-Organic Chemical Vapor Deposition (MOCVD) process using antimony chloride (SbCl 3 ) and bis(trimethylsilyl)telluride (Te(SiMe 3 ) 2 ) as precursors. Pre-growth and post-growth treatments were found to be pivotal in favoring out-of-plane and in-plane alignment of the crystallites composing the films. A comprehensive suite of characterization techniques were used to evaluate their composition, surface roughness, as well as to assess their morphology, crystallinity, and structural features, revealing that a quick post-growth annealing triggers the formation of epitaxial-quality Sb 2 Te 3 films on Si(111)., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Hybrid organo-lead halide perovskites are becoming the benchmark material for next generation photovoltaics and a very important player for other applications such as photodetectors and light emitting diodes. Nevertheless, the most important issue hindering the large-scale application of these materials remains their intrinsic instability due to the organic cation. Although the substitution with inorganic cesium (Cs) enhances stability, in most cases solution deposition methods of fully inorganic perovskites result in high surface roughness and poor surface coverage. This work reports on the evaporation of the CsPbBr 3 precursor by Single Source Thermal Ablation, showing that just after deposition films consist of a mixture of CsPbBr 3 , CsPb 2 Br 5 , and Cs 4 PbBr 6 due to a vertical composition gradient. We point out that mild post deposition treatments lead to the conversion of CsPb 2 Br 5 and Cs 4 PbBr 6 into CsPbBr 3 due to its higher thermodynamic stability. Conversion results into smooth and pinhole-free CsPbBr 3 films with good light absorption and emission properties. We demonstrate the suitability of obtained films for planar devices by preparing perovskite-based pure-green light emitting diodes, thus promoting Single Source Thermal Ablation as a promising alternative deposition technique for all-inorganic perovskite-based devices., (Copyright © 2020 Nasi, Calestani, Mezzadri, Mariano, Listorti, Ferro, Mazzeo and Mosca.)