Ferromagnetism in bare gold nanoagglomerates produced by nanocluster deposition

Abstract Recent research has shown unconventional magnetic properties in nanosized gold systems. These effects have mostly been detected in functionalized gold nanoparticles as well as in gold nanocrystalline films. We demonstrate ferro- and superparamagnetic behaviour in assemblies of bare gold nanoclusters. This is demonstrated by the characteristic ferromagnetic hysteresis with the temperature dependent saturation magnetization, remanence and coercivity in aggregates of small clusters. The detected magnetization is caused by the interaction between the separate clusters exhibiting an core-shell structure, and dependent on the total amount of gold confined in the samples. The behaviour is analogous to that of transition metal clusters.Peer reviewe

Conventional Nanoindentation in Self-Assembled Monolayers Deposited on Gold and Silver Substrates

Peer reviewe

Crystalline tungsten sulfide thin films by atomic layer deposition and mild annealing

Tungsten disulfide (WS2) is a semiconducting 2D material, which is gaining increasing attention in the wake of graphene and MoS2 owing to its exciting properties and promising performance in a multitude of applications. Herein, the authors deposited WSx thin films by atomic layer deposition using W-2(NMe2)(6) and H2S as precursors. The films deposited at 150 degrees C were amorphous and sulfur deficient. The amorphous films crystallized as WS2 by mild postdeposition annealing in H2S/N-2 atmosphere at 400 degrees C. Detailed structural characterization using Raman spectroscopy, x-ray diffraction, and transmission electron microscopy revealed that the annealed films consisted of small (Peer reviewe

Atomic Layer Deposition of CsI and CsPbI3

Cesium iodide (CsI) is a well-established scintillator material that also serves as a precursor for all-inorganic halide perovskite solar absorbers, such as CsPbI3. However, the lack of conformal and scalable methods to deposit halide perovskite thin films remains a major challenge on their way to commercialization. In this work, we employ atomic layer deposition (ALD) as the key method due to its inherent scalability to large areas and complex-shaped surfaces. We demonstrate two new ALD processes for the deposition of CsI and CsPbI3 thin films. The CsI process relies on cesium bis(trimethylsilyl) amide (Cs(btsa)) and tin(IV) iodide (SnI4) as precursors and yields high-purity, uniform, and phase-pure thin films. This process works in a wide temperature range (140-350 degrees C) and exhibits a large growth per cycle value (GPC) of 3.3 angstrom (85% of a CsI monolayer). Furthermore, we convert CsI into CsPbI3 perovskite by exposing a CsI film to our earlier PbI2 ALD process. We demonstrate the deposition of phase-pure gamma- or delta-CsPbI3 perovskite thin films, depending on the applied deposition temperature and number of PbI2 cycles. We believe that the ALD-based approach described in this work will offer a viable alternative for depositing perovskite thin films in applications that involve complex high aspect ratio structures or large substrate areas.Peer reviewe

Conversion of ALD CuO Thin Films into Transparent Conductive p-Type CuI Thin Films

Copper iodide (CuI) is a high-performance p-type transparent semiconductor that can be used in numerous applications, such as transistors, diodes, and solar cells. However, the lack of conformal and scalable methods to deposit CuI thin films limits its establishment in applications that involve complex-shaped and/or large substrate areas. In this work, atomic layer deposition (ALD) is employed to enable scalable and conformal thin film deposition. A two-step approach relying on ALD of CuO and its subsequent conversion to CuI via exposure to HI vapor at room temperature is demonstrated. The resulting CuI films are phase-pure, uniform, and of high purity. Furthermore, CuI films on several substrates such as Si, amorphous Al2O3, n-type TiO2, and gamma-CsPbI3 perovskite are prepared. With the resulting n-TiO2/p-CuI structure, the easy and straightforward fabrication of a diode structure as a proof-of-concept device is demonstrated. Moreover, the successful deposition of CuI on gamma-CsPbI3 proves the compatibility of the process for using CuI as the hole transport layer in perovskite solar cell applications in the nip-configuration. It is believed that the ALD-based approach described in this work will offer a viable alternative for depositing transparent conductive p-type CuI thin films in applications that involve complex high aspect ratio structures and large substrate areas.Peer reviewe

Critical temperature modification of low dimensional superconductors by spin doping

Ion implantation of Fe and Mn into Al thin films was used for effective modification of Al superconductive properties. Critical temperature of the transition to superconducting state was found to decrease gradually with implanted Fe concentration. it was found that suppression by Mn implantation much stronger compared to Fe. At low concentrations of implanted ions, suppression of the critical temperature can be described with reasonable accuracy by existing models, while at concentrations above 0.1 at.% a pronounced discrepancy between the models and experiments is observed.Comment: 7 figures, 18 page

Hydrogen isotope exchange experiments in high entropy alloy WMoTaNbV

Plasma–facing components in future fusion reactors must endure high temperatures as well as high fluxes and fluences of high energy particles. Currently tungsten has been chosen as the primary plasma-facing material due to its good thermal conductivity, low erosion rate and low fuel retention. Materials with even better properties are still being investigated to be used in reactor regions with demanding plasma conditions. High entropy alloys (HEA) are a new class of metallic alloys and their exploitation in fusion applications has not been widely studied. In this work, the hydrogen isotope exchange effect in an equiatomic HEA containing W, Mo, Ta, Nb, and V was studied. Deuterium was implanted into HEA samples with 30 keV/D energy and the HEA and reference samples were annealed in H2 atmosphere and in vacuum at various temperatures up to 400 °C, respectively. The near-surface D concentration profiles were measured with ERDA and the isotope exchange was observed to remove over 90 % of the trapped deuterium from the implantation region at temperatures above 200 °C. TDS was used to measure retention deeper in the bulk in which the reduction of trapped deuterium was significantly lower. High total retention of H was found in the bulk after H2 atmosphere annealing which indicates permeation and deep trapping of H in the material.Plasma-facing components in future fusion reactors must endure high temperatures as well as high fluxes and fluences of high energy particles. Currently tungsten has been chosen as the primary plasma-facing material due to its good thermal conductivity, low erosion rate and low fuel retention. Materials with even better properties are still being investigated to be used in reactor regions with demanding plasma conditions. High entropy alloys (HEA) are a new class of metallic alloys and their exploitation in fusion applications has not been widely studied. In this work, the hydrogen isotope exchange effect in an equiatomic HEA containing W, Mo, Ta, Nb, and V was studied. Deuterium was implanted into HEA samples with 30 keV/D energy and the HEA and reference samples were annealed in H2 atmosphere and in vacuum at various temperatures up to 400 °C, respectively. The near-surface D concentration profiles were measured with ERDA and the isotope exchange was observed to remove over 90 % of the trapped deuterium from the implantation region at temperatures above 200 °C. TDS was used to measure retention deeper in the bulk in which the reduction of trapped deuterium was significantly lower. High total retention of H was found in the bulk after H2 atmosphere annealing which indicates permeation and deep trapping of H in the material.Peer reviewe

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Corporate Responsibility in the Food Chain: The Criteria and Indicators

Corporate responsibility (CR) is becoming a key issue in the food chain. In order to make sense of this phenomenon, a seminal aper by Maloni and Brown (2006) called for further empirical investigation on the criteria of responsibility in the food supply chain. The purpose of this paper is to answer the call by identifying the criteria for defining CR and develop indicators for measuring the responsibility performance of the food chain.The study was based on interactive and participatory stakeholder dialogues with diverse experts, corporate representatives and other stakeholders, including non-governmental organizations (NGOs) and governmental bodies. Through an iterative research process we identified the criteria and developed the indicators. Our findings enable business leaders to evaluate and manage their operations towards more responsible business praxis

Fabrication and characterization of vacuum deposited fluorescein thin films

Simple vacuum evaporation technique for deposition of dyes on various solid surfaces has been developed. The method is compatible with conventional solvent-free nanofabrication processing enabling fabrication of nanoscale optoelectronic devices. Thin films of fluorescein were deposited on glass, fluorine-tin-oxide (FTO) coated glass with and without atomically layer deposited (ALD) nanocrystalline 20 nm thick anatase TiO2 coating. Surface topology, absorption and emission spectra of the films depends on their thickness and the material of supporting substrate. On a smooth glass surface the dye initially formes islands before merging into a uniform layer after 5 to 10 monolayers. On FTO covered glass the absorption spectra are similar to fluorescein solution in ethanol. Absorption spectra on ALD-TiO2 is red shifted compared to the film deposited on bare FTO. The corresponding emission spectra at {\lambda} = 458 nm excitation show various thickness and substrate dependent features, while the emission of films deposited on TiO2 is quenched due to the effective electron transfer to the semiconductor conduction band.Comment: 24 pages including 5 figure