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Using N2O as an alternative background gas to O2 when growing oxide thin films by pulsed laser deposition (PLD) was previously expected to result in larger oxygen contents of as-grown thin films. In this work, we investigate the composition and kinetic energy of the pulsed laser induced plasmas that propagated in N2O and O2 by using mass spectrometry and plasma imaging. Two distinguished features were observed when using N2O instead of O2. (1) In N2O background gas as compared to O2, a larger proportion of negative oxygen ions was detected. (2) The alkaline-earth elements were fully oxidized in the N2O background, which is not achievable in O2. These observations are attributed to the smaller dissociation energy of the N2O molecules as compared to O2. The smaller dissociation energy of the background gas molecule is expected to reduce the interaction strength during their central collisions with the plasma species. As a result, the dissociable or electron detachable plasma species can be formed in larger amounts in N2O background, compared to O2. Comparing the composition of the deposited thin films indicates a larger oxygen content of the film grown in N2O background gas, as compared to O2, at pressures of ∼10−1 mbar, which is the most commonly used deposition pressure in PLD. Nevertheless, this was not achieved when performing PLD at ∼10−2 mbar, since the pressure was not high enough to trigger the formation of the shockwave front during the plasma expansion and thereby the lightest oxygen plasma species were preferentially scattered. [ABSTRACT FROM AUTHOR]

The Capillary Heavy Ion MeV-SIMS Probe (CHIMP) at ETH Zürich has been redesigned with a second mass spectrometer and symmetric extraction to enable simultaneous analysis of positive and negative secondary ions. Secondary electrons are deflected within the negative spectrometer and detected independently. The fast secondary electron signal is used as a start signal for both Time-of-Flight mass spectrometers. The new setup enables the simultaneous acquisition and analysis of both secondary ion polarities emitted under identical conditions from the same sample location. This allows to study correlations between secondary ions of different polarities emitted from a single primary ion impact. Measurements with small primary C n cluster ions show the influence of cluster size on the multiplicity of secondary ion emission. Furthermore, a cluster effect in the ratio between positive and negative ion yields of corresponding secondary ion species is identified, with the ratio approaching parity for larger cluster sizes n. [ABSTRACT FROM AUTHOR]

In this work, we have quantitatively elucidated the source of the hydrogen content in the atomic layer deposition of Al2O3 at different temperatures (80-220 °C), by replacing the H2O precursor with heavy water (D2O) to use as a tracer and discern between the H coming from the unreacted metal precursor ligands and that from the unreacted -OD (hydroxyl) groups coming from the (heavy) water. The main source of impurities arises from the unreacted hydroxyl groups (-OD), reaching ~18 atom % of deuterium at a deposition temperature of 80 °C. Reconsidering carefully our own and literature experimental data, we concluded that the generally accepted mechanism of steric hindering by monodentate Al(CH3)2 adsorbates (dimethylaluminum) cannot be solely responsible for the retention of hydroxyls during atomic layer deposition (ALD). On this regard, we propose two additional mechanisms that can lead to sterically hinder hydroxyl groups which will then remain unreacted in the film: surface rehydroxylation resulting in the reconfiguration of bidentate or tridentate adsorbates into monodentate adsorbates and hindered subsurface hydroxyl groups during the (heavy) water pulse and the hydroxylation of sterically hindered dissociated methyl chemisorbed species. Based on these three steric hindrance mechanisms, we constructed a growth model that consists of the initial chemisorption configurations of trimethyl-aluminum molecules with the alumina surface and the subsequent reconfiguration of the resulting adsorbates into a monodentate configuration that consequently leads to sterically hindered hydroxyl groups. The fraction of AlOx adsorbates arranged in monodentate and bidentate configurations entails a specific number of O/Al atoms and unreacted hydroxyl groups inside the film. This model was able to explain the deuterium content, the O/Al ratio, and the density obtained from Rutherford back-scattering and heavy ion elastic recoil detection analysis measurements. Furthermore, this model was able to predict more accurately the growth per cycle to what has been reported to be the ALD window of alumina. Our findings will spur further detailed investigations of the reaction and growth modes in ALD films. [ABSTRACT FROM AUTHOR]

The operation of the ETH gas ionization detector as a proportional chamber, where a secondary ionization avalanche is initiated between the Frisch grid and anode, was investigated for ions covering the mass range from H to 127 I. By amplifying the detector electron signal through secondary ionization, the limitations due to the sensitivity of the detector electronics are minimized. It could be demonstrated that in the energy range of a few hundreds of keV and below a proportional chamber clearly outperforms a conventionally used gas ionization detector. Protons below 10 keV were measured with a resolution better than 1.4 keV and a good linearity of the particle energy and detector signal was found in the energy range between 50 and 1000 keV. At higher energies almost no difference in resolution for the two operation modes could be found. [ABSTRACT FROM AUTHOR]

The pre-treatment of substrate surfaces prior to deposition is important for the adhesion of physical vapour deposition coatings. This work investigates Si surfaces after the bombardment by energetic Cr ions which are created in cathodic arc discharges. The effect of the pre-treatment is analysed by X-ray diffraction, Rutherford backscattering spectroscopy, scanning electron microscopy and in-depth X-ray photoemission spectroscopy and compared for Cr vapour produced from a filtered and non-filtered cathodic arc discharge. Cr coverage as a function of ion energy was also predicted by TRIDYN Monte Carlo calculations. Discrepancies between measured and simulated values in the transition regime between layer growth and surface removal can be explained by the chemical reactions between Cr ions and the Si substrate or between the substrate surface and the residual gases. Simulations help to find optimum and more stable parameters for specific film and substrate combinations faster than trial-and-error procedure. [ABSTRACT FROM AUTHOR]

A new Time-of-flight MeV Secondary Ion Mass Spectrometry (MeV-SIMS) setup was developed to be used with a capillary microprobe for molecular imaging with heavy primary ions at MeV energies. Due to the low output current of the ion collimating capillary a Time-of-flight (ToF) measurement method with high duty cycle is necessary. Secondary electrons from the sample surface and transmitted ions were studied as start signals. They enable measurements with a continuous primary beam and unpulsed ToF spectrometer. Tests with various primary ion beams and sample types have shown that a secondary electron signal is obtained from 30% to 40% of incident MeV particles. This provides a ToF start signal with considerably better time resolution than the one obtained from transmitted primary ions detected in a radiation hard gas ionization detector. Beam induced secondary electrons therefore allow for MeV-SIMS measurements with reasonable mass resolution at primary ion beam currents in the low fA range. [ABSTRACT FROM AUTHOR]

A new compact Bragg type gas ionization chamber (GIC) has been built for use as particle counter in AMS and IBA applications. The detector stands out due to its simple concept, which does not include a Frisch grid. Test experiments have been performed with ions in the mass range from He to Th and energies ranging from 30 keV to 2.5 MeV, in order to find optimal measurement conditions and to characterize the detector performance. For projectiles heavier than Al at energies below 2.5 MeV the obtained energy resolution is comparable with that of a state-of-the-art GIC with Frisch grid and clearly outperforms solid state detectors. Additionally the operation of this simplified Bragg GIC in the electron multiplication mode was investigated for the first time, which allows the detection of radiocarbon ions at energies below 50 keV with an energy resolution of the order of 10 keV. [ABSTRACT FROM AUTHOR]

Plasma chemistry and scattering strongly affect the congruent, elemental transfer during pulsed laser deposition of target metal species in an oxygen atmosphere. Studying the plasma properties of La0.6Sr0.4MnO3, we demonstrate for as grown La0.6Sr0.4MnO3-δ films that a congruent transfer of metallic species is achieved in two pressure windows: ~10−3 mbar and ~2 × 10−1 mbar. In the intermediate pressure range, La0.6Sr0.4MnO3-δ becomes cation deficient and simultaneously almost fully stoichiometric in oxygen. Important for thin film growth is the presence of negative atomic oxygen and under which conditions positive metal-oxygen ions are created in the plasma. This insight into the plasma chemistry shows why the pressure window to obtain films with a desired composition and crystalline structure is narrow and requires a careful adjustment of the process parameters. [ABSTRACT FROM AUTHOR]

Abstract: Cathodic arc evaporation was utilized to synthesize Cr–N, ta–C, Al–Mo–N, Mo–N, Mo–O–N and Mo–Cu–N coatings. The coatings were characterized with respect to their stoichiometry, morphology and mechanical properties. A reciprocating wear test was used to compare the wear behavior for the unpolished coatings under dry conditions and polished coatings under lubricated (Mo-DTC) conditions. The test allows a classification of the coatings with respect to material transfer similar to scuffing or fretting and with respect to wear of the counter-part and may be utilized for a pre-selection of coatings for engine tests. [Copyright &y& Elsevier]

Abstract: Al–Cr–O layers were synthesized by reactive cathodic arc evaporation utilizing DC as well as pulsed operation of the arc sources. The observed increase of the substrate ion current in the pulsed mode is attributed to the increased ionization of the oxygen reactive gas. The influence of the substrate ion current and the oxygen flow on the microstructure of the layers has been investigated. A strong influence of the oxygen gas flow on morphology and crystal structure has been observed. The increased substrate ion current in the pulsed mode has seemingly no influence on layer morphology at low bias voltages, but influences the nucleation behavior of the layer. The appearance of a multi-layer structure in the synthesized layers utilizing a single composite target has been ascribed to partial ion splitting of the target constituents in the curvilinear arc discharge. [Copyright &y& Elsevier]

[Display omitted] • The hydrophobicity of IBS Y 2 O 3 films was tested for different sputter parameters. • The residual Ar-content of the film plays a decisive role for the hydrophobicity. • Higher O to Y ratio improves the hydrophobicity. • Y 2 O 3 terminated Y 2 O 3 :SiO 2 nanolaminates are hydrophobic. The wettability and the control of the contact angle of surfaces are important for various applications. Materials with a water contact angle less than or greater than 90 deg are hydrophilic or hydrophobic, respectively. Most of the binary oxides are hydrophilic, but oxides of rare earth metals and metal atoms with low electronegativity have hydrophobic surfaces. Yttria is one of the materials predicted to have hydrophobic properties. In this work, we investigated the wettability of ion-beam-sputtered Yttria thin films. The measured water contact angles were between 67° and 96°. The concentration of the embedded argon atoms was found to influence the contact angle. [ABSTRACT FROM AUTHOR]

Abstract: Isotopic ratios of 10Be/9Be with a background sensitivity of 2×10−14 can now be measured with the 0.6MV Tandem accelerator of PSI/ETH Zurich using BeF2 instead of BeO as sample material and injecting BeF− to suppress the boron detector count rate. A new, high-resolution gas ionization detector with a thin silicon nitride entrance window and special preamplifier design are essential in order to achieve this sensitivity. A particle transmission of 50% is possible for charge state 1+. Due to the maximum count rate that can be accepted by the detector the BeF− currents are limited to a few hundred nA. Measurements of 10Be in rainwater samples performed under these conditions at the low terminal voltage of 0.6MV with the new compact AMS system show good agreement with results using the conventional 10Be measurement setup on the 6MV facility. Thus, this type of small scale equipment can now also be applied for 10Be AMS as long as 10Be/9Be ratios are sufficiently high and measurement time is not a limiting factor. Instead, using BeO and the degrader foil technique with a silicon nitride membrane the boron count rate can also be suppressed sufficiently but the 10Be/9Be background level is limited to 10−13 by scattered 9Be and the overall transmission is less than 5%. [Copyright &y& Elsevier]

Abstract: Special gas ionisation detectors have been developed for AMS at low energies (0.3–3MeV). By using very thin silicon nitride foils as entrance windows and low-noise preamplifiers, significant improvements in the performance has been obtained. In addition, electronic noise has been reduced by a compact design which minimises cable length and input capacitance. The resolution has been systematically studied as a function of energy for various projectiles ranging from protons to uranium. Energy straggling in the thin entrance foil is only a minor contribution to the total energy resolution. For heavier ions z p >6 the resolution is limited by the statistical nature of the ionisation process in the counter gas. For light elements, the electronic noise is the dominant contribution to the resolution. Particle identification with ΔE − E techniques has been studied as well. Good isobar separation for 10Be–10B can be obtained in the energy range of 0.3–0.8MeV. Also isobaric molecules such as BeH and CH can be identified in the energy range of 1MeV. These advances in detector performance represent an essential step forward in the development of multi-isotope AMS facilities at low energies. The detector development has also a potential for application in other fields of research where good energy resolution and particle identification is needed. [Copyright &y& Elsevier]

Abstract: The 600kV AMS facility at ETH/PSI has been upgraded to a universal platform for AMS at low energies allowing to perform studies of 10Be, 14C, 26Al, 41Ca, 129I, 236U and Pu. The most significant improvement in performance is due to a new gas ionisation chamber of much better energy resolution. Performance for 10Be, 14C, 26Al, 129I and Pu isotopes is now competitive with larger AMS facilities. The background in 41Ca measurements is sufficiently low to measure samples for biomedical applications. [Copyright &y& Elsevier]

A design for a novel tabletop AMS system is presented. The mini radiocarbon dating system (MICADAS) is based on an acceleration unit that uses vacuum to insulate the high-voltage terminal. The acceleration voltage (200 kV) is supplied by a commercially available power supply. A gas stripper is used to charge exchange the negative ions extracted from the ion source into charge state 1+ and to break up the interfering molecules of mass 14 amu in multiple collisions. Cross-sections of these molecular break up processes in the energy range 220–590 keV are presented. The primary component of the new instrument, the acceleration unit, is now operational. Test measurements of the unit in combination with the mass spectrometers of the compact PSI/ETH Pelletron based AMS system have been successfully made. First results demonstrate the capability of radiocarbon dating at 200 kV terminal voltage. [Copyright &y& Elsevier]

In the previous paper (Part I), the colorimetry and interferometric microscopy measurements on modern gold leaf models have revealed that the visual appearance of a gilded surface, both burnished and unburnished, depends strongly on the substrate type, surface roughness and texture, but not on the colour of the substrate. In this second part, we investigate the materials compositions and technical specifications of medieval gold leaf through combining literature sources and materials analysis such as scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM–EDX) on samples taken from gilded wooden sculptures. Our study shows that the late medieval gold leaf has a high purity of about 23.7 carat and has an average thickness of 160 nm (with a peak value of 138 nm), purer and thicker than the modern gold leaves studies in Part I. Supportive Rutherford backscattering spectrometry (RBS) measurements on gilded models confirms the accuracy and reliability of the SEM–EDX observations on the medieval gold leaf samples. We additionally present observations of a rarely recorded special variant of medieval gold leaf—"fine reinforced gold leaf". Combined with the findings from Part I, we conclude that light penetrating the medieval gold leaf and reflected from the gilding substrate could not be a significant, or even perceptible contribution to the visual appearance of the gilding. We argue that the misconception surrounding the correlation between the substrate colour and the gilded surface appearance can be attributed to the historical development of gilding and polychromy technologies. [ABSTRACT FROM AUTHOR]

The effects of the type of background gas and pressure on the spatial distributions of plume species have been investigated by time and space resolved imaging in vacuum, 1×10-2 mbar and 1×10-1 mbar O2 and Ar. The ablation of La0.4Ca0.6MnO3 in vacuum shows dissimilar arrival times for the different neutral species and a backscattering of the impinging species from the substrate. At 1×10-2 mbar, a species-dependent plume splitting appears and preferential scattering of the lighter elements is detected generating a cation off-stoichiometry along the plume axis. In addition at 1×10-1 mbar the plume expansion in this relatively high pressure traps a portion of the background gas against the substrate holder, thereby creating a transient high local pressure with remarkable effects once the plume reaches the substrate. In an Ar background, a rebound wave is seen, which travels backwards and recoats/contaminates the target with a different composition than the original target. In O2, in addition to the rebound, a long-lived volume of excited species is created, which consists mainly of LaO I. The rebound has important effects on the film composition and is background gas dependent. The same effects are also detected during Ag ablation and are probably valid for most target materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Focused study aiming at technological parameters of corroded Mediaeval Zwischgold. • Gold layer in a nanoscale thickness range of 20–50 nm, with the peak at 30 nm. • Full foil thickness (50–260 nm) obtained from EDX derived Ag/Au weight ratio. • Ultra-high-resolution SEM measurements, supported by STEM and RBS. • Scientific evidence for paleness of Zwischgold. A special gilding material called Zwischgold has been frequently observed in medieval gilded artefacts. As a bilayer metal leaf made from gold and silver, it exhibits similar but slightly paler golden colour tone compared to pure gold. Zwischgold surface can be darkened quickly due to the corrosion of its silver base. Despite its frequent mentions in medieval guild statutes, the production of Zwischgold and its important technological parameters have been under a veil of secrecy since the Middle Ages. Here, we examine the thicknesses and materials proportions of medieval Zwischgold, through high-resolution scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM-EDX) on a large number of samples taken from late medieval gilded sculptures. We observe that medieval Zwischgold contains ultra-thin gold layers in a thickness range of ca. 20–50 nm, indicating the employment of high-precision technologies in manufacturing of delicate art materials in the late medieval period. It further clarifies some ambiguity in gilding history, regarding the colour appearance of medieval Zwischgold. As supportive data, Rutherford backscattering spectrometry (RBS) and scanning transmission electron microscopy (STEM) were applied, in order to confirm the precision and accuracy of the sample preparation and the SEM analysis. [ABSTRACT FROM AUTHOR]

The development of non-noble nano-porous metal materials is hindered by surface oxidation reactions and from the difficulty to generate long range order pore arrays. Dealloying is a promising route to generate such materials by selective chemical etching of metal alloy materials. This process can generate nano-metal materials with superior plasmonic, catalytic and adsorptive surface properties. Here, the impact of properties of the etching solution on the dealloying process to generate nano-pores across thin film alloys was investigated by in-situ SAXS dealloying experiments. Single phase CuZn alloys were used as model materials to evaluate the influence of the solution temperature on the pore formation kinetics. This novel analysis allowed to visualize the change in surface properties of the materials over time, including their surface area as well as their pore and ligament sizes. The dealloying kinetics at the very early stage of the process were found to be critical to both stable pore formation and stabilization. SAXS in-situ data were correlated to the morphological properties of the materials obtained from ex-situ samples by Rutherford back scattering and scanning electron microscopy. [ABSTRACT FROM AUTHOR]

With high resistance against interdiffusion, electromigration, creep and fatigue, single-crystal films of refractory metals are highly desired for applications in opto- and micro-electronic devices. Their fabrication is nevertheless very challenging, primarily due to their high melting points. Requiring no external thermal input, ion-irradiation presents an alternative route for single-crystal films by converting from their polycrystalline counterparts through irradiation-induced selective grain growth. The incomplete poly- to single-crystal conversion is however a common problem which limits the application of this method. Here we use refractory W thin films, the element with the highest melting point, as a model system. We systematically investigate the influences of film microstructure (texture and grain size) and irradiation temperature (77 K and room temperature) on the evolution of selective grain growth under 4.5 MeV Au+ ion-irradiation. We find that the driving force for selective grain growth can be increased by narrowing the texture spread of the films, refining the grain size and decreasing the irradiation temperature. Following this guidance, a complete conversion of a polycrystalline W film into a single crystal is achieved. This study therefore provides insights into the mechanism of selective grain growth and proves that it is an effective technique for microstructure engineering in thin film materials. The concepts can be applied to all crystalline metal films. Image, graphical abstract [ABSTRACT FROM AUTHOR]

An MeV-SIMS microprobe has been constructed based on primary beam collimation by a conical glass capillary. Molecular surface mapping is obtained by raster scanning of the sample with a piezo-driven XY stage. The angular divergence of the collimated beam is smaller than 0.3 mrad, which allows a relatively large distance between capillary exit and sample without a significant loss in lateral resolution. With a capillary of 5 μm outlet diameter a lateral resolution of approximately 10 μm has been observed at a working distance of 50 mm. Capillary collimation can be obtained in a very simple and inexpensive fashion and is virtually independent of the used beam particle properties over a large range of ion mass and energy. [ABSTRACT FROM AUTHOR]

Typical low-temperature frustrated triangular antiferromagnet CuFeO2 is attracting extensive interest due to its narrow-band-gap semiconductor properties. High-quality and impurity-free CuFeO2 epitaxial thin films would be preferable for fundamental studies on the physical and chemical properties. However, the heteroepitaxial growth of impurity-free CuFeO2 thin films has been a significant challenge due to its narrow formation window in the Cu–Fe–O system as well as the metastable nature of the Cu1+ cations. This work reports for the first time the fabrication and characterization of high-quality and impurity-free (00.1)-oriented CuFeO2 epitaxial thin films grown with relaxed interfaces on (00.1) sapphire substrates by pulsed laser deposition. Below the critical thickness of around 16 nm, the films exhibit a rhombohedral structure with relatively good crystalline quality where all Cu ions appear to be in the 1+ oxidation state, while the rocking curves display a narrow full width at half maximum of about 0.11°. Increasing the thickness, the (111)-oriented γ-Fe2O3 nanograins grow embedded in the CuFeO2 films. Here, an excess Fe3+-assisted growth mechanism is proposed to explain the iron oxide grain formation. This study provides insight into the heteroepitaxial growth of relaxed CuFeO2 thin films with high purity and crystalline quality as an ideal sample design to characterize the fundamental properties of this material in view of potential device applications. [ABSTRACT FROM AUTHOR]

Angle-resolved thickness and compositional analyses of BaTiO 3 , CaTiO 3 , La 0.4 Ca 0.6 MnO 3 , EuAlO 3 , and LiMn 2 O 4 were performed to study the influence of the background gas pressure when depositing multi-elemental oxide materials . With increasing gas pressure the typical forward directed deposition changes to a constant thickness at all angles. Compositional changes with respect to the target show dependencies on (in order of influence): target material, deposition pressure, and angular location (substrate size). A linear relationship was found between target mass-ratios and compositional deviations. This can lead to compositional deviations of up to 70% for large mass-ratios in certain pressure regimes. [ABSTRACT FROM AUTHOR]

In pulsed laser deposition the use of a rectangular or elliptical beam spot with a non 1:1 aspect ratio leads to the so called flip-over effect. Here, the longest dimension of the laser spot results in the shortest direction of plasma plume expansion. This effect has been mainly reported for vacuum depositions of single element targets and is particularly noticeable when the aspect ratio of the beam spot is large. We investigate the flip-over effect in vacuum and at three relevant background-gas pressures for pulsed laser deposition using a La 0.4 Ca 0.6 MnO 3 target by measuring the thickness dependence of the deposited material as a function of angle. The film thicknesses and compositions are determined by Rutherford backscattering and argon is used to reduce the influence of additional chemical reactions in the plasma. The results show the prevalence of the flip-over effect for all pressures except for the highest, i.e. 1 × 10 −1 mbar, where the film thickness is constant for all angles. The composition profiles show noticeable compositional variations of up to 30% with respect to the target material depending on the background gas pressure, the angular location, and the laser spot dimensions. [ABSTRACT FROM AUTHOR]

Among cathode materials, LiNi0.8Mn0.1Co0.1O2 (NMC811) is the most discussed for high performance Li‐ion batteries, thanks to its capacity of ≈200 mAh g‐1 and low Co content. Here, it is demonstrated that NMC811 can reversibly accommodate more than one Li‐ion per formula unit when coupled with a solid‐state electrolyte, thus significantly increasing its capacity. Sputtered Li‐rich NMC811 cathodes are tested with lithium–phosphorus–oxynitride as a solid‐state electrolyte in a thin‐film architecture, which is a simplified 2D model with direct access to the cathode‐electrolyte interface. The solid‐state electrolyte helps to stabilize the interface and prevents capacity fading, voltage decay, and interface resistance growth, thus allowing cycling at extended voltage ranges of 1.5–4.7 V. While the liquid electrolyte cells suffer from rapid capacity decay, the Li‐rich NMC811 cells with the solid‐state electrolyte can cycle at a fast rate and an initial capacity of 149 mAh g‐1 from 1.5 to 4.3 V for 1000 cycles. The all‐solid‐state thin‐film cells with a lithium metal anode yield a discharge capacity of up to 350 mAh g‐1 at C/10 because of multi‐electron cycling with a coulombic efficiency of 90.1%. The results demonstrate how solid‐state electrolytes that are stable against NMC811 cathodes can unlock the full potential of this Li‐rich and Ni‐rich cathode class. [ABSTRACT FROM AUTHOR]

Different SrTiO3 thin films are investigated to unravel the nature of ultra‐low conductivities recently found in SrTiO3 films prepared by pulsed laser deposition. Impedance spectroscopy reveals electronically pseudo‐intrinsic conductivities for a broad range of different dopants (Fe, Al, Ni) and partly high dopant concentrations up to several percent. Using inductively‐coupled plasma optical emission spectroscopy and reciprocal space mapping, a severe Sr deficiency is found and positron annihilation lifetime spectroscopy revealed Sr vacancies as predominant point defects. From synchrotron‐based X‐ray standing wave and X‐ray absorption spectroscopy measurements, a change in site occupation is deduced for Fe‐doped SrTiO3 films, accompanied by a change in the dopant type. Based on these experiments, a model is deduced, which explains the almost ubiquitous pseudo‐intrinsic conductivity of these films. Sr deficiency is suggested as key driver by introducing Sr vacancies and causing site changes (FeSr and TiSr) to accommodate nonstoichiometry. Sr vacancies act as mid‐gap acceptor states, pinning the Fermi level, provided that additional donor states (most probably TiSr••\[{\rm{Ti}}_{{\rm{Sr}}}^{ \bullet \bullet }\]) are present. Defect chemical modeling revealed that such a Fermi level pinning also causes a self‐limitation of the Ti site change and leads to a very robust pseudo‐intrinsic situation, irrespective of Sr/Ti ratios and doping. [ABSTRACT FROM AUTHOR]

The angular distribution of species from a La 0.4 Ca 0.6 MnO 3 target irradiated with a 248 nm nanosecond pulsed laser was investigated by Rutherford backscattering spectrometry for four different Ar pressures. The film thickness angular distribution was also analyzed using profilometry. Depending on the background gas pressure, the target to substrate distance, and the angular location the film thickness and composition varies considerably. In particular the film composition could vary by up to 17% with respect to the composition of the target material. [ABSTRACT FROM AUTHOR]

With pulsed laser deposition, we have grown c axis oriented thin films of the nominal composition LaMnO3 (LMO) on LSAT(001) substrates. We find that, depending on the oxygen background pressure during growth, the LMO films contain sizeable amounts of La and/or Mn vacancies that strongly influence their electronic and magnetic properties. Specifically, we show that the Mn/La ratio can be systematically varied from 0.92 at 0.11 mbar to 1.09 at 0.30 mbar of oxygen. The cationic vacancies have markedly different effects that become most pronounced once the samples are fully oxygenated and thus strongly hole doped. All as-grown and thus slightly oxygen-deficient LMO films are ferromagnetic insulators with saturation moments in excess of 2.5 μB per Mn ion, their transport and optical properties can be understood in terms of trapped ferromagnetic polarons. Upon oxygen annealing, the most La-deficient films develop a metallic response with an even larger ferromagnetic saturation moment of 3.8 μB per Mn ion. In contrast, in the oxygenated Mn-deficient films, the ferromagnetic order is strongly suppressed to less than 0.5 μB per Mn ion, and the transport remains insulatorlike. We compare our results with the ones that were previously obtained on bulk samples and present an interpretation in terms of the much stronger disruption of the electronic and magnetic structure by the Mn vacancies as compared to the La vacancies. We also discuss the implications for the growth of LMO thin films with well-defined physical properties that are a prerequisite for the study of interface effects in multilayers. [ABSTRACT FROM AUTHOR]

Abstract: The radiation resistance of two promising ferritic ODS steels, PM2000 and 15CRA-3, is studied. More specifically, the effect of helium on these materials is studied by examining the swelling and hardening after He+ implantation to ∼1dpa at 4000appm/dpa. White light interferometry is used to measure the post-irradiation surface displacement whereas mirco-hardness measurements are carried out to determine the radiation hardening. These methods prove to be very efficient and fast working, thus making good statistics obtainable in a reasonable time. Low swelling is found in both alloys, although the PM2000 shows a lower resistance, with an increased swelling of ∼0.8%dpa−1 at 600°C, while the 15CRA-3 presents an almost constant swelling of around 0.4%dpa−1 throughout the complete temperature range. Radiation hardening follows a similar trend, whereby hinting towards an annealing mechanism taking place at the interfaces between the very fine distribution of Y2O3 nanoparticles and the matrix, interfaces which act as sites of enhanced point defect recombination as well as traps for the implanted helium. [Copyright &y& Elsevier]

The misfit-layered cobalt oxide [Ca2CoO3-δ][CoO2]1.62 is a promising material for high-temperature thermoelectric heat recovery. Here, we show that discrepancies in the numerously reported thermoelectric performances can result from Co3OM4 impurities or a change of the defects, i.e., the relative Co content in the [Ca2CoO3-δ][CoO2]1.62 phase. We observe that increasing the relative Co content in the [Ca2CoO3-δ][CoO2]1.62 phase leads to a larger figure of merit ZT. We attribute this increase of ZT to additional p-type charge carriers introduced by Ca vacancies and the resulting reduction of the electrical resistivity. For Co/Ca ratios above the miscibility limit, the increase in thermal conductivity due to the formation of Co3OM4 impurities leads to a reduction of ZT when the volume fraction of the Co3OM4 phase is increased from 1% to 3%. Hence, the best figure of merit is expected close to the upper phase boundary of the [Ca2CoO3-δ][CoO2]1.62 phase. [ABSTRACT FROM AUTHOR]

Abstract: Ion-bombardment-induced selective grain growth is a process that allows for full control of the orientation of vapor-deposited thin films, which can be converted from fiber-textured polycrystalline to single-crystal films. The main mechanisms behind this phenomenon are explained by a new thermal spike model, which takes into account and compares the different driving forces governing the film microstructure evolution upon irradiation and emphasizes the importance of the thermal spike shape and volume. The strong agreement between model and experimental data confirms that selective grain growth is driven by the minimization of the volume free energy. [Copyright &y& Elsevier]

Rubrene single crystals have been irradiated with 1-MeV protons and helium ions at various fluence levels (0.1 x 1012--5 x 1012 particles/cm2), and the resulting increase of the density of bulk trap states (DOS) has been studied by temperature-dependent space-charge-limited current measurements. Irradiation creates a peak in the trap DOS (about 1016 traps/cm3 for a radiation dose of ≈35 J/g), centered at ≈0.35 eV above the valence band edge. With incrementally increasing radiation dose, the induced trap density rises sublinearly and saturates at high dose. Three to five times more traps are created if the crystal surface is not covered during irradiation. We attribute this trap creation primarily to C-H bond breaking accompanied by hydrogen loss. [ABSTRACT FROM AUTHOR]

Abstract: Thin Al–Cr–O films are proposed as hydrogen permeation barriers. Layers of a few microns in thickness are able to suppress hydrogen permeability by a factor of 2000 to 3500 at temperatures of 700 °C, as has been found in our gas phase permeation experiments. We attribute this excellent efficiency to a dense layer morphology and the possible (pre)-formation of solid solutions in corundum-type structure. These films are deposited by pulsed arc evaporation in a batch-type production system at substrate temperatures of 550 °C. [Copyright &y& Elsevier]

Pulsed reactive crossed-beam laser ablation is an effective technique to govern the chemical activity of plasma species and background molecules during pulsed laser deposition. Instead of using a constant background pressure, a gas pulse with a reactive gas, synchronized with the laser beam, is injected into vacuum or a low background pressure near the ablated area of the target. It intercepts the initially generated plasma plume, thereby enhancing the physicochemical interactions between the gaseous environment and the plasma species. For this study, kinetic energy resolved mass-spectrometry and time-resolved plasma imaging were used to study the physicochemical processes occurring during the reactive crossed beam laser ablation of a partially 18O substituted La0.6Sr0.4MnO3 target using oxygen as gas pulse. The characteristics of the ablated plasma are compared with those observed during pulsed laser deposition in different oxygen background pressures. [ABSTRACT FROM AUTHOR]

High mobility hydrogenated indium oxide is investigated as a transparent contact for thin film Cu(In,Ga)Se2 (CIGS) solar cells. Hydrogen doping of In2O3 thin films is achieved by injection of H2O water vapor or H2 gas during the sputter process. As-deposited amorphous In2O3:H films exhibit a high electron mobility of ~50 cm²/Vs at room temperature. A bulk hydrogen concentration of ~4 at. % was measured for both optimized H2O and H2-processed films, although the H2O-derived film exhibits a doping gradient as detected by elastic recoil detection analysis. Amorphous IOH films are implemented as front contacts in CIGS based solar cells, and their performance is compared with the reference ZnO:Al electrodes. The most significant feature of IOH containing devices is an enhanced open circuit voltage (VOC) of ~20 mV regardless of the doping approach, whereas the short circuit current and fill factor remain the same for the H2O case or slightly decrease for H2. The overall power conversion efficiency is improved from 15.7% to 16.2% by substituting ZnO:Al with IOH (H2O) as front contacts. Finally, stability tests of non-encapsulated solar cells in dry air at 80 °C and constant illumination for 500 h demonstrate a higher stability for IOH-containing devices. [ABSTRACT FROM AUTHOR]

Polycrystalline tungsten-substituted CaMn1-xWxO3-δ (0.00 ≤ x ≤ 0.05) powders were synthesized from a polymeric precursor, pressed and sintered to high density. The impact of tungsten substitution on the crystal structure, thermal stability, phase transition, electronic and thermal transport properties is assessed. Tungsten acts as an electron donator and strongly affects high-temperature oxygen stoichiometry. Oxygen vacancies form in the high figure-of-merit (ZT)-region starting from about T = 1000 K and dominate the carrier concentration and electronic transport far more than the tungsten substitution. The analysis of the transport properties yields that in the investigated regime the band filling is sufficiently high to overcome barriers of polaron transport. Therefore, the Cutler-Mott approach describes the electrical transport more accurately than the Mott approach for small polaron transport. The lattice thermal conductivity near room temperature is strongly suppressed with increasing tungsten concentration due to mass-difference impurity scattering. A ZT of 0.25 was found for x = 0.04 at 1225 K. [ABSTRACT FROM AUTHOR]

Electron probe and ion probe are the two most used instruments for in situ analysis of halogens in geological materials. The comparison of these two methods on widely distributed glass standards (example: MPI-DING glasses, Jochum et al., G-cubed, 2006) provides a basis for establishing laboratory method, independent geochemical data sets for these elements. We report analyses of F, S, and Cl concentrations in three geological glass samples (EPMA) and 10 referenced standards (EPMA and SIMS). Furthermore, F and Cl absolute abundances have been determined independently for three of the standards (KL2-G, ATHO-G, and KE12), via heavy ion elastic recoil detection analysis (HIERDA), to certify the accuracy of the cross-calibration EPMA-SIMS. The detection limits for EPMA are a 150 mg·g-1 for F, 20 mg·g-1 for S and Cl, and for SIMS < 48 mg·g-1 for F, < 3 mg·g-1 for S, and <19 mg·g-1 for Cl. On SiO2-rich glass-standards, F and Cl measurements by HIERDA highlight a weak matrix effect during SIMS analysis of F and Cl. With the HIERDA independently measured value, we therefore propose an alternative calibration function to empirically correct this matrix effect on the SIMS measurements of F, S, and Cl. [ABSTRACT FROM AUTHOR]

TiO 2 and WO 3 are two of the most important earth-abundant electronic materials with applications in countless industries. Recently alloys of WO 3 and TiO 2 have been investigated leading to improvements of key performance indicators for a variety of applications ranging from photo-electrochemical water splitting to electrochromic smart windows. These positive reports and the complexity of the ternary W-Ti-O phase diagram motivate a comprehensive experimental screening of this phase space. Using combinatorial thermal oxidation of solid solution W 1- x Ti x precursors combined with bulk and surface analysis mapping we investigate the oxide phase formation and surface passivation of tungsten titanium oxide in the entire compositional range from pure WO 3 to TiO 2. The system shows a remarkable structural transition from monoclinic over cubic to tetragonal symmetry with increasing Ti concentration. In addition, a strong Ti surface enrichment is observed for precursor Ti-concentrations in excess of 55 at.%, resulting in the formation of a protective rutile-structured TiO 2 surface layer. Despite the structural transitions, the optical properties of the oxide alloys remain largely unaltered demonstrating an independent control of multiple functional properties in W 1- x Ti x O n. The results from this study provide valuable guidelines for future development of W 1- x Ti x O n for electronic and energy applications, but also novel engineering approaches for surface functionalization and additive manufacturing of Ti-based alloys. Using combinatorial thermal oxidation of solid solution W 1- x Ti x precursors combined with bulk and surface analysis mapping we investigate the oxide phase formation and surface passivation of tungsten titanium oxide in the entire compositional range from pure WO 3 to TiO 2. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Pulsed laser deposition (PLD) is commonly used to grow thin film materials with complex stoichiometry and crystal structures, since it achieves a congruent transfer of the target cation elements to the substrate. Although the incongruent PLDs were previously observed via regulating the plasma/background interaction regimes, the incongruent PLDs were seldom investigated and applied practically for the thin film depositions. Herein, we demonstrate the incongruent pulsed laser deposition of Ca 3 Co 4 O 9 thermoelectric thin films, via regulating the target compositions and the oxygen background pressures to preferential scattering the plasma cation compositions. To compare the deposition properties via incongruent and congruent thin film growth, we systematically investigate the crystal structures, surface morphologies, elemental distributions and thermoelectric transportation behaviors for Ca 3 Co 4 O 9 thin films grown at various target compositions and background pressure ranges. A stoichiometric Ca 3 Co 4 O 9 thin film composition is achievable via designing an incongruent PLD strategy, in which case the Ca/Co ratios in the targets are enlarged actively while the PLDs are performed at a pressure range of 100 Pa to further preferential scatter of the lighter Ca compared to Co. Nevertheless, the incongruently grown thin films exhibit lower thermoelectric performances, compared to the one at a similar composition grown via the congruent PLD strategy. This result may associate to the localized composition inhomogeneity in the Ca 3 Co4O 9 grown incongruently, and their electronical resistivities are largely elevated by the resultant impurities that are hardly detectable by X-ray diffractions. The present work reveals the complexity in deposition mechanism and kinetics when performing incongruent PLDs, in particular, for growing multiple elemental thin film materials. [ABSTRACT FROM AUTHOR]

Zwischgold is a two-sided metal foil made by adhering a gold leaf over a silver leaf to present a gold surface while using less gold than gold foils. Corroded Zwischgold surfaces appear dark, accompanied by gloss loss and possible mechanical stability issues. Zwischgold applied artefacts are commonly found in museums and churches across Europe and they currently face an uncertain future as conservators have little knowledge to base conservation treatments on. We present a comprehensive material analysis of Zwischgold models through advanced characterization techniques including focused ion beam coupled with scanning electron microscopy (FIB-SEM), transmission electron microscopy (TEM), scanning transmission X-ray microscopy (STXM), time-of-flight secondary ion mass spectrometry (TOF-SIMS) and Rutherford backscattering spectrometry (RBS). Complementary information on the foil thickness, sharpness of the gold-silver interface, gold purity, and the formation as well as distribution of corrosion products on Zwischgold models have been obtained, representing a starting point for understanding the morphology and the long-term chemistry of Zwischgold artefacts. [ABSTRACT FROM AUTHOR]

The size of the band gap and the energy position of the band edges make several oxynitride semiconductors promising candidates for efficient hydrogen and oxygen production under solar light illumination. Intense research efforts dedicated to oxynitride materials have unveiled the majority of their most important properties. However, two crucial aspects have received much less attention: One is the critical issue of compositional/structural surface modifications that occur during operation and how these affect photoelectrochemical performance. The second concerns the relation between electrochemical response and the crystallographic surface orientation of the oxynitride semiconductor. These are indeed topics of fundamental importance, since it is exactly at the surface where the visible-light-driven electrochemical reaction takes place. In contrast to conventional powder samples, thin films represent the best model system for these investigations. This study reviews current state-of-the-art oxynitride thin film fabrication and characterization, before focusing on LaTiO2N, selected as a representative photocatalyst. An investigation of the initial physicochemical evolution of the surface is reported. Then, it is shown that after stabilization the absorbed photon-to-current conversion efficiency of epitaxial thin films can differ by about 50% for different crystallographic surface orientations, and be up to 5 times larger than for polycrystalline samples. [ABSTRACT FROM AUTHOR]

The single-step reaction of benzene and boron tribromide in a closed reactor at elevated temperature (800 °C) results in the synthesis of bulk boron-doped graphitic carbon. Materials of continuously tunable composition BCx' are accessible (x ≥ 3), exhibiting the structure of a solid-solution of boron within turbostratic graphite (G'). Upon extended heat treatment or at higher temperatures, graphitic BCx' is leached of boron and undergoes a phase separation into boron carbide and graphite. Higher boron content is correlated with an increased maximum capacity for alkali metal ions, making graphitic BCx' a promising candidate anode material for emerging sodium-ion batteries. [ABSTRACT FROM AUTHOR]

Developing novel materials for the conversion of solar to chemical energy is becoming an increasingly important endeavour. Perovskite compounds based on bandgap tunable oxynitrides represent an exciting class of novel photoactive materials. To date, literature mostly focuses on the characterization of oxynitride powder samples which have undeniable technological interest but do not allow the investigation of fundamental properties such as the role of the crystalline quality and/or the surface crystallographic orientation toward photo-catalytic activity. The challenge of growing high quality oxynitride thin films arises from the availability of a suitable substrate, owing to strict material and processing requirements: effective lattice matching, sufficiently high conductivities, stability under high temperatures and in strongly reducing environments. Here, we have established the foundations of a model system incorporating a TiN-buffer layer which enables fundamental investigations into crystallographic surface orientation and crystalline quality of the photocatalyst against photo(electro)chemical performance to be effectively performed. Furthermore, we find that TiN as current collector enables control over the nitrogen content of oxynitride thin films produced by a modified pulsed laser deposition method and allows the growth of highly ordered LaTiO 3− x N x thin films. [ABSTRACT FROM AUTHOR]

We investigate how excitonic processes in rubrene single crystals are affected by a deliberately implanted defect gradient induced by proton irradiation. Spatially resolved measurements show a gradually reduced photoluminescence quantum yield and triplet exciton diffusion length along the defect gradient. Both effects are caused by a decrease in the average triplet lifetime due to interaction with the implanted defects. The triplet lifetime was reduced by almost two orders of magnitude at the highest implanted defect density of 1017cm-3. The strong sensitivity of the photoluminescence quantum yield to the defect density that is observed already at moderate excitation densities is caused by the combination of two effects: the dominant contribution of triplet-fusion to the observed photoluminescence and the long-range diffusion of triplet excitons. [ABSTRACT FROM AUTHOR]

The introduction of a KF postdeposition treatment (KF PDT) of Cu(In,Ga)Se2 (CIGS) thin films has led to the achievement of several consecutive new world record efficiencies up to 21.7% for the CIGS solar cell technology. The beneficial effect of the KF PDT on the photovoltaic parameters was observed by several groups in spite of differing growth methods of the CIGS layer. For CIGS evaporated at lower temperature on alkali-free, flexible plastic substrates, a postdeposition treatment to add Na was already successfully applied. However, with the introduction of additional KF under comparable conditions, distinctly different influences on the final absorber alkali content as well as surface properties are observed. In this work we discuss in more detail the intrinsically different role of both alkali-treatments by combining several microstructural and compositional analysis methods. The ion exchange of Na by K in the bulk of the absorber is carefully analyzed, and further evidence for the formation of a K-containing layer on the CIGS surface with increased surface reactivity is given. These results shall serve as a basis for the further understanding of the effects of alkali PDT on CIGS and help identify research needs to achieve even higher efficiencies. [ABSTRACT FROM AUTHOR]

The introduction of a KF postdeposition treatment (KF PDT) of Cu(In,Ga)Se2 (CIGS) thin films has led to the achievement of several consecutive new world record efficiencies up to 21.7% for the CIGS solar cell technology. The beneficial effect of the KF PDT on the photovoltaic parameters was observed by several groups in spite of differing growth methods of the CIGS layer. For CIGS evaporated at lower temperature on alkali-free, flexible plastic substrates, a postdeposition treatment to add Na was already successfully applied. However, with the introduction of additional KF under comparable conditions, distinctly different influences on the final absorber alkali content as well as surface properties are observed. In this work we discuss in more detail the intrinsically different role of both alkali-treatments by combining several microstructural and compositional analysis methods. The ion exchange of Na by K in the bulk of the absorber is carefully analyzed, and further evidence for the formation of a K-containing layer on the CIGS surface with increased surface reactivity is given. These results shall serve as a basis for the further understanding of the effects of alkali PDT on CIGS and help identify research needs to achieve even higher efficiencies. [ABSTRACT FROM AUTHOR]

Electron doping by hydrogenation can reversibly modify the electrical properties of complex oxides. We show that in order to realize large, fast, and reversible response to hydrogen, it is important to consider both the electron configuration on the transition metal 3d orbitals, as well as the thermodynamic stability in nickelates. Specifically, large doping-induced resistivity modulations ranging several orders of magnitude change are only observed for rare earth nickelates with small ionic radii on the A-site, in which case both electron correlation effects and the meta-stability of Ni3+ are important considerations. Charge doping via metastable incorporation of ionic dopants is of relevance to correlated oxide-based devices where advancing approaches to modify the ground state electronic properties is an important problem. [ABSTRACT FROM AUTHOR]

Electron doping by hydrogenation can reversibly modify the electrical properties of complex oxides. We show that in order to realize large, fast, and reversible response to hydrogen, it is important to consider both the electron configuration on the transition metal 3d orbitals, as well as the thermodynamic stability in nickelates. Specifically, large doping-induced resistivity modulations ranging several orders of magnitude change are only observed for rare earth nickelates with small ionic radii on the A-site, in which case both electron correlation effects and the meta-stability of Ni3+ are important considerations. Charge doping via metastable incorporation of ionic dopants is of relevance to correlated oxide-based devices where advancing approaches to modify the ground state electronic properties is an important problem. [ABSTRACT FROM AUTHOR]