| 1. |
|
|
| 2. |
|
|
| 3. |
- Adalsteinsson, Sigurbjörn Már, et al.
(författare)
-
Correlating chemical composition and optical properties of photochromic rare-earth oxyhydrides using ion beam analysis
- 2020
-
Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : ELSEVIER. - 0168-583X .- 1872-9584. ; 485, s. 36-40
-
Tidskriftsartikel (refereegranskat)abstract
- We relate the photochromic response of rare-earth oxyhydride thin films (YHO, NdHO, GdHO and DyHO) synthesized by reactive magnetron sputtering to chemical composition. Depth profiles of the sample composition are extracted by a multi-method ion beam analysis approach. The total areal density of the thin films is deduced from Rutherford Backscattering Spectrometry while coincidence Time-of-Flight/Energy Elastic Recoil Detection Analysis provides depth-profiles of the film constituents. High-resolution depth profiles of the concentration of light species, i.e. hydrogen and oxygen, are additionally extracted from Nuclear Reaction Analysis and Elastic Backscattering Spectrometry, respectively. The photochromic response of the films is measured by optical transmission spectroscopy before and after illumination. We report photochromic properties for YHO, NdHO, GdHO and DyHO for chemical compositions described by the formula REH2-delta O delta in the range of 0.45 < 6 < 1.5.
|
|
| 4. |
- Assar, Alireza, et al.
(författare)
-
Gettering in PolySi/SiOx Passivating Contacts Enables Si-Based Tandem Solar Cells with High Thermal and Contamination Resilience
- 2022
-
Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 14:12, s. 14342-14358
-
Tidskriftsartikel (refereegranskat)abstract
- Multijunction solar cells in a tandem configuration could further lower the costs of electricity if crystalline Si (c-Si) is used as the bottom cell. However, for direct monolithic integration on c-Si, only a restricted number of top and bottom cell architectures are compatible, due to either epitaxy or high-temperature constraints, where the interface between subcells is subject to a trade-off between transmittance, electrical interconnection, and bottom cell degradation. Using polySi/SiOx passivating contacts for Si, this degradation can be largely circumvented by tuning the polySi/SiOx stacks to promote gettering of contaminants admitted into the Si bottom cell during the top cell synthesis. Applying this concept to the low-cost top cell chalcogenides Cu2ZnSnS4 (CZTS), CuGaSe2 (CGSe), and AgInGaSe2 (AIGSe), fabricated under harsh S or Se atmospheres above 550 degrees C, we show that increasing the heavily doped polySi layer thickness from 40 to up to 400 nm prevents a reduction in Si carrier lifetime by 1 order of magnitude, with final lifetimes above 500 mu s uniformly across areas up to 20 cm(2). In all cases, the increased resilience was correlated with a 99.9% reduction in contaminant concentration in the c-Si bulk, provided by the thick polySi layer, which acts as a buried gettering layer in the tandem structure without compromising the Si passivation quality. The Si resilience decreased as AIGSe > CGSe > CZTS, in accordance with the measured Cu contamination profiles and higher annealing temperatures. An efficiency of up to 7% was achieved for a CZTS/Si tandem, where the Si bottom cell is no longer the limiting factor.
|
|
| 5. |
- Baba, Elbruz Murat, et al.
(författare)
-
Preferential Orientation of Photochromic Gadolinium Oxyhydride Films
- 2020
-
Ingår i: Molecules. - : MDPI. - 1431-5157 .- 1420-3049. ; 25:14
-
Tidskriftsartikel (refereegranskat)abstract
- We report preferential orientation control in photochromic gadolinium oxyhydride (GdHO) thin films deposited by a two-step process. Gadolinium hydride (GdH2-x) films were grown by reactive magnetron sputtering, followed by oxidation in air. The preferential orientation, grain size, anion concentrations and photochromic response of the films were strongly dependent on the deposition pressure. The GdHO films showed a preferential orientation along the [100] direction and exhibited photochromism when synthesized at deposition pressures of up to 5.8 Pa. The photochromic contrast was larger than 20% when the films were deposited below 2.8 Pa with a 0.22 H-2/Ar flow ratio. We argue that the relation of preferential orientation and the post deposition oxidation since oxygen concentration is known to be a key parameter for photochromism in rare-earth oxyhydride thin films. The experimental observations described above were explained by the decrease of the grain size as a result of the increase of the deposition pressure of the sputtering gas, followed by a higher oxygen incorporation.
|
|
| 6. |
- Biber, Herbert, et al.
(författare)
-
Solar wind Helium ion interaction with Mg and Fe rich pyroxene as Mercury surface analogue
- 2020
-
Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : ELSEVIER. - 0168-583X .- 1872-9584. ; 480, s. 10-15
-
Tidskriftsartikel (refereegranskat)abstract
- The surface of Mercury is continuously exposed to impinging solar wind ions. To improve the understanding of space weathering and exosphere formation, a detailed investigation of the ion-surface interaction is necessary. Magnesium and iron rich pyroxene (Ca,Mg,Fe)(2)[Si2O6] samples were used as analogues for Mercury's surface and irradiated with He+ ions at solar wind energies of 4 keV. Several regimes of implantation and sputtering were observed there. The total estimated mass of implanted He coincides with the mass decrease due to He outgassing during subsequent Thermal Desorption Spectroscopy measurements. Comparison to established modeling efforts and SDTrimSP simulations show that a He saturation concentration of 10 at.% has to be assumed. A complete removal of He is observed by heating to 530 K. On the surface of Mercury, temperatures between about 100 K and 700 K are expected. This temperature will therefore influence the implantation and release of He into Mercury's exosphere.
|
|
| 7. |
- Biber, H., et al.
(författare)
-
Sputtering Behavior of Rough, Polycrystalline Mercury Analogs
- 2022
-
Ingår i: The Planetary Science Journal. - : Institute of Physics (IOP). - 2632-3338. ; 3:12
-
Tidskriftsartikel (refereegranskat)abstract
- The solar wind continuously impacts on rocky bodies in space, eroding their surface, thereby contributing significantly to the exosphere formations. The BepiColombo mission to Mercury will investigate the Hermean exosphere, which makes an understanding of the precise formation processes crucial for evaluation of the acquired data. We therefore developed an experimental setup with two microbalances that allows us to compare the sputter behavior of deposited thin solid layers with that of real mineral samples in the form of pressed powder. In addition, this technique is used to study the angular distribution of the sputtered particles. Using 4 keV He+ and 2 keV Ar+ ions, the sputter behavior of pellets of the minerals enstatite (MgSiO3) and wollastonite (CaSiO3) is studied, because these minerals represent analogs for the surface of the planet Mercury or the Moon. Pellets of powdered enstatite show significantly lower sputter yields than thin amorphous enstatite films prepared by pulsed laser deposition. 3D simulations of sputtering based on surface topography data from atomic force microscopy show that the observed reduction can be explained by the much rougher pellet surface alone. We therefore conclude that sputter yields from amorphous thin films can be applied to surfaces of celestial bodies exposed to ion irradiation, provided the effects of surface roughness, as encountered in realistic materials in space, are adequately accounted for. This also implies that taking surface roughness into account is important for modeling of the interaction of the solar wind with the surface of Mercury.
|
|
| 8. |
- Ciuciulkaite, Agne, MSc, 1991-, et al.
(författare)
-
Magnetic and all-optical switching properties of amorphous TbxCo100-x alloys
- 2020
-
Ingår i: Physical Review Materials. - : American Physical Society (APS). - 2475-9953. ; 4:10
-
Tidskriftsartikel (refereegranskat)abstract
- Amorphous TbxCo100-x magnetic alloys exhibit a list of intriguing properties, such as perpendicular magnetic anisotropy, high magneto-optical activity, and magnetization switching using ultrashort optical pulses. Varying the Tb:Co ratio in these alloys allows for tuning properties such as the saturation magnetic moment, coercive field, and the performance of light-induced magnetization switching. In this paper, we investigate the magnetic, optical, and magneto-optical properties of various TbxCo100-x thin-film alloy compositions. We report on the effect the choice of different seeding layers has on the structural and magnetic properties of TbxCo100-x layers. We also demonstrate that for a range of alloys, deposited on fused silica substrates, with Tb content of 24-30 at. %, helicity-dependent all-optical switching of magnetization can be achieved, albeit in a multishot framework. We explain this property to arise from the helicity-dependent laser-induced magnetization on the Co sublattice due to the inverse Faraday effect. Our paper provides an insight into material aspects for future potential hybrid magnetoplasmonic TbCo-based architectures.
|
|
| 9. |
- Comparotto, Corrado, et al.
(författare)
-
Chalcogenide Perovskite BaZrS3 : Thin Film Growth by Sputtering and Rapid Thermal Processing
- 2020
-
Ingår i: ACS Applied Energy Materials. - : AMER CHEMICAL SOC. - 2574-0962. ; 3:3, s. 2762-2770
-
Tidskriftsartikel (refereegranskat)abstract
- Tandem solar cells based on hybrid organic-inorganic metal halide perovskites have reached efficiencies up to 28%, but major concerns for long-term stability and the presence of Pb have raised interest in searching for fully earth-abundant, intrinsic chemically stable, and nontoxic alternatives. With a direct band gap around 1.8 eV and stability in air up to at least 500 degrees C, BaZrS3 is a promising candidate. This work presents the first approach of synthesizing a thin film of such compound by sputtering at ambient temperature with a subsequent rapid thermal process. Despite the short fabrication time, the width of the XRD diffraction peaks and the energy and distribution of the photoluminescence response show comparable crystalline quality to that from bulk synthesis methods. Good crystallization required around 900 degrees C. Such a high temperature could be incompatible with fabrication of tandem solar cells.
|
|
| 10. |
- Cupak, C., et al.
(författare)
-
Absence of synergistic effects in quasi-simultaneous sputtering of tungsten by Ar and D ions
- 2023
-
Ingår i: Nuclear Materials and Energy. - : Elsevier. - 2352-1791. ; 35
-
Tidskriftsartikel (refereegranskat)abstract
- A quartz crystal microbalance was used to experimentally study the erosion of tungsten during rapidly alternating bombardment with 2 keV argon and deuterium projectiles. A key goal was to investigate whether the mean sputtering yield of the alternating irradiation can be predicted from data for sputtering yields of single ion species. In addition, influences by residual gas pressure in the UHV experiment and variable ion fluxes have been studied. Our results show that the mean sputtering yield of irradiations with alternating ion species can be well predicted for a range of different fluence ratios as a simple superposition of individual sputtering yields, weighted by the respective relative fluences. This finding supports that no synergistic sputtering effects were relevant in the investigated low-flux regime.
|
|
| 11. |
- Cupak, C., et al.
(författare)
-
Retention of deuterium in beryllium : A combined investigation using TDS, ERDA and EBS
- 2022
-
Ingår i: Nuclear Materials and Energy. - : Elsevier. - 2352-1791. ; 33
-
Tidskriftsartikel (refereegranskat)abstract
- We have studied the retention of deuterium in beryllium, implanted with an energy of 500 eV/D, using a combination of thermal desorption spectroscopy, elastic recoil detection analysis and elastic backscattering spectroscopy. The parallel use of these techniques allowed us to directly quantify the absolute deuterium content reduction of the sample for specific desorption peaks observed during thermal annealing. In addition, the presence of a beryllium oxide surface layer was observed, despite sputter-cleaning of the sample was initially conducted in-situ. A main result was that similar to 85 % of the retained deuterium got released during the primary desorption peak at 400 K. A smaller, secondary desorption peak was identified at 540 K. All deuterium could be removed from the Be sample by heating it to a temperature of 800 K.
|
|
| 12. |
- Cupak, C., et al.
(författare)
-
Sputter yields of rough surfaces : Importance of the mean surface inclination angle from nano- to microscopic rough regimes
- 2021
-
Ingår i: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; 570
-
Tidskriftsartikel (refereegranskat)abstract
- The roughness of a surface is known to have a strong influence on the sputtering process. Commonly used 1D Monte Carlo codes for calculating sputter yields show good agreement with experimental data only for comparably flat surfaces, whereas local ion incidence angles, shadowing and redeposition influence the sputter yields in both magnitude and angular dependence on rough surfaces. In the present work, we therefore investigated tungsten samples of largely different roughness, characterised by atomic force and confocal microscopy. A highly sensitive quartz crystal microbalance was used to determine sputter yields during ion irradiation. Low ion fluences were applied to ensure that the surface morphology did not change during irradiation. The results were used to benchmark our new ray-tracing simulation code SPRAY, which can take microscopy images without limitations in size as input. SPRAY was furthermore applied to perform systematic simulations for artificially roughened and computer-generated surfaces. A clear result was that the governing parameter for description of the sputtering behaviour is the mean value of the surface inclination angle distribution, rather than the commonly used root mean square roughness. Our simulations show that this parameter is universally applicable for a wide range of different surface structures.
|
|
| 13. |
- Englund, Sven, et al.
(författare)
-
Antimony-Doped Tin Oxide as Transparent Back Contact in Cu2ZnSnS4 Thin-Film Solar Cells
- 2019
-
Ingår i: Physica Status Solidi (a) applications and materials science. - : Wiley. - 1862-6300 .- 1862-6319. ; 216:22
-
Tidskriftsartikel (refereegranskat)abstract
- Antimony-doped tin oxide (Sn2O3:Sb, ATO) is investigated as a transparent back contact for Cu2ZnSnS4 (CZTS) thin-film solar cells. The stability of the ATO under different anneal conditions and the effect from ATO on CZTS absorber growth are studied. It is found that ATO directly exposed to sulfurizing anneal atmosphere reacts with S, but when covered by CZTS, it does not deteriorate when annealed at T < 550 degrees C. The electrical properties of ATO are even found to improve when CZTS is annealed at T = 534 degrees C. At T = 580 degrees C, it is found that ATO reacts with S and degrades. Analysis shows repeatedly that ATO affects the absorber growth as large amounts of Sn-S secondary compounds are found on the absorber surfaces. Time-resolved anneal series show that these compounds form early during anneal and evaporate with time to leave pinholes behind. Device performance can be improved by addition of Na prior to annealing. The best CZTS device on ATO back contact herein has an efficiency of 2.6%. As compared with a reference on a Mo back contact, a similar open-circuit voltage and short-circuit current density are achieved, but a lower fill factor is measured.
|
|
| 14. |
- Hans, Marcus, et al.
(författare)
-
Photochromic Mechanism and Dual-Phase Formation in Oxygen-Containing Rare-Earth Hydride Thin Films
- 2020
-
Ingår i: Advanced Optical Materials. - : WILEY-V C H VERLAG GMBH. - 2162-7568 .- 2195-1071. ; 8:19
-
Tidskriftsartikel (refereegranskat)abstract
- The phase formation of a photochromic Gd-0.31(H0.55O0.45)(0.69)thin film, grown by reactive magnetron sputtering, is critically evaluated. Oxygen is preferably incorporated into the underdense columnar grain boundaries, when the as-deposited gadolinium hydride film is exposed to ambient conditions. Two phases, Gd(2)O(3)and GdH2, are formed with significant compressive residual stress of 5.9 +/- 1.5 GPa. These findings, extracted from transmission electron microscopy, X-ray diffraction and atom probe tomography, provide a straightforward explanation for the photochromic effect. The mechanism can be understood as photon-induced hydrogen transfer between the two phases, identical in nature to the photochromic effect in bulk yttrium hydride at high pressure.
|
|
| 15. |
- Kantre, Karim-Alexandros, et al.
(författare)
-
Assessing electronic energy loss of heavy ions detected in reflection geometry
- 2021
-
Ingår i: Surface and Interface Analysis. - : John Wiley & Sons. - 0142-2421 .- 1096-9918. ; 53:7, s. 650-657
-
Tidskriftsartikel (refereegranskat)abstract
- We study energy loss spectra of bromine ions scattered from silver thin films in the range of 4 to 36 MeV in forward reflection geometry. The different contributions to the energy loss were analyzed by complementary Monte-Carlo simulations. We assess the dependence of the scattering yield as well as nuclear and electronic losses on the penetration depth of detected ions. To investigate the entanglement of energy loss and depth information, electronic stopping cross sections were deduced from the experimental spectra by two different approaches: a) assuming a single scattering model and b) making use of Monte-Carlo simulations. The data obtained from the two approaches are compared and we assess the relative contributions from nuclear stopping as well as from the effect of multiple scattering on trajectory length. Results of both methods are compared to data from literature, to SRIM predictions and discussed in the context of composition depth‑profiling.
|
|
| 16. |
- Kantre, Karim-Alexandros, et al.
(författare)
-
Combination of in-situ ion beam analysis and thermal desorption spectroscopy for studying deuterium implanted in tungsten
- 2021
-
Ingår i: Physica Scripta. - : Institute of Physics Publishing (IOPP). - 0031-8949 .- 1402-4896. ; 96:12
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a combinatorial approach integrating ion implantation followed by thermal annealing and simultaneous in situ ion beam analysis with thermal desorption spectroscopy in a single set-up. Atomic and molecular deuterium ions of 3 keV were implanted into bulk tungsten with doses exceeding 1 x 10(22) ions m(-2). Depth profiling of both, protium and deuterium was performed by elastic recoil detection analysis, while simultaneously the outgassing rates of molecular deuterium by thermal desorption spectroscopy were monitored during temperature ramps from room temperature to approximate to 1400 K. The combination of the two techniques in situ is shown capable to identify the distinct retention behavior of deuterium at different temperatures and in different reservoirs, e.g. located close to the surface and diffused deep into the material. Ex-situ scanning electron microscopy confirmed blister formation, and recovery of the initial surface morphology after high temperature annealing, in analogy to comprehensive ex-situ studies.
|
|
| 17. |
- Kantre, Karim-Alexandros, et al.
(författare)
-
SIGMA : A Set-up for In-situ Growth, Material modification and Analysis by ion beams
- 2020
-
Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : ELSEVIER. - 0168-583X .- 1872-9584. ; 463, s. 96-100
-
Tidskriftsartikel (refereegranskat)abstract
- We present a set-up for in-situ non-destructive high-resolution composition depth profiling by ion beams developed at the 5 MV 15 SDH-2 Tandem accelerator at the Angstrom laboratory at Uppsala University. The scattering chamber allows thin film deposition, modification and characterization which can be used to study the very initial stages of near-surface processes such as thin film growth, oxidation, annealing or ion implantation. We describe the available instrumentation with its specifications in detail and present experimental applications, i.e. the characterization of reactive in-situ thin film growth and controlled oxidation, as well as a study of ion implantation and the impact of thermal annealing and surface oxidation on the implantation profiles.
|
|
| 18. |
- Kantre, Karim-Alexandros, et al.
(författare)
-
Synthesis and in-situ characterization of photochromic yttrium oxyhydride grown by reactive e--beam evaporation
- 2020
-
Ingår i: Scripta Materialia. - : Elsevier BV. - 1359-6462 .- 1872-8456. ; 186, s. 352-356
-
Tidskriftsartikel (refereegranskat)abstract
- We report on controlled growth of photochromic yttrium oxyhydride thin films monitored by in-situ composition depth profiling. Films were grown by reactive e(-)-beam evaporation and subsequently oxidized, while simultaneously tracking the oxygen and hydrogen concentrations. Sample composition and photochromic response were characterized in-situ using non-destructive ion beam analysis and image analysis, respectively - as well as complementary ex-situ ion beam methods, X-ray diffraction and optical spectrophotometry. We show that photochromic yttrium oxyhydride can be grown as yttrium dihydride, which is then oxidized to O/H ratios triggering the photochromic response.
|
|
| 19. |
- Kazi, Suraya, et al.
(författare)
-
Correlating Photoconductivity and Optical Properties in Oxygen-Containing Yttrium Hydride Thin Films
- 2023
-
Ingår i: Physica Status Solidi. Rapid Research Letters. - : Wiley-VCH Verlagsgesellschaft. - 1862-6254 .- 1862-6270. ; 17:5
-
Tidskriftsartikel (refereegranskat)abstract
- Oxygen-containing yttrium hydride (YHO), primarily known for its photochromic properties, simultaneously shows a photoconductive response. Polycrystalline YHO thin films are deposited by reactive magnetron sputtering onto glass substrates and their optical and electrical properties are correlated under illumination with light. While photoconductivity is found in a broader range of compositions than photochromism, maximum photoconductive response is found for samples exhibiting photochromism. This photoconductive effect can be observed above a certain cutoff energy of light and a stronger response is triggered by shorter wavelengths. After the illumination is stopped, the slow recovery (few minutes) of the optical transmission and electrical transport suggests that the underlying process is not purely electronic. A memory effect is found depending on the previous exposure of samples to light which supports the hypothesis of local hydrogen diffusion during the photochromic reaction. An unprecedentedly fast bleaching speed is reported for samples stored in vacuum immediately after film deposition.
|
|
| 20. |
- Komander, Kristina, et al.
(författare)
-
Hydrogen induced lattice expansion and site occupation analyzed by ion beam methods
- 2021
-
Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier. - 0168-583X .- 1872-9584. ; 486, s. 63-67
-
Tidskriftsartikel (refereegranskat)abstract
- We study the absorption of H in ultrathin crystalline Fe/V stacks using elastic recoil detection (ERD) and resonant nuclear reaction analysis (NRA) combined with Rutherford backscattering spectrometry (RBS). Probing with the resonant H-1 (N-15,alpha gamma) C-12 nuclear reaction allows us to profile the hydrogen concentration with high depth resolution, while ERD permits us to quantify the integral hydrogen inventory while minimizing possible ionbeam induced hydrogen desorption. We perform angular scans in order to directly identify the interstitial site occupancy. A detailed analysis of channeling patterns permits us the deduction of crystal strain in as-deposited films as well as H-loaded targets. We observe tetragonal strain formation resulting in c/a = 1.06 and find qualitative indications for tetrahedral site occupation.
|
|
| 21. |
- Komander, Kristina, et al.
(författare)
-
Hydrogen site location in ultrathin vanadium layers by N-15 nuclear reaction analysis
- 2019
-
Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : ELSEVIER. - 0168-583X .- 1872-9584. ; 455, s. 57-60
-
Tidskriftsartikel (refereegranskat)abstract
- We present a method using resonant nuclear reaction analysis combined with optical transmission and heavy-ion Rutherford backscattering spectrometry to study the absorption of hydrogen in single crystalline thin vanadium films. Probing with the resonant H-1(N-15,alpha gamma)C-12 reaction allows for highly resolved hydrogen depth profiling, while measurements along the crystal axes render possible the direct identification of the interstitial site occupancy. First experiments were performed on thin vanadium hydrides in Fe(Cr)/V superlattices revealing differences in site occupancy.
|
|
| 22. |
- Komander, Kristina, et al.
(författare)
-
Interstitial Hydrogen in Fe/V Superstructures : Lattice Site Location and Thermal Vibration
- 2021
-
Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 127:13
-
Tidskriftsartikel (refereegranskat)abstract
- We report real space location of hydrogen in single crystalline Fe/V superstructures. Anisotropic strain is quantified versus hydrogen concentration by using the yield of backscattered primary 2 MeV He-4 ions for incidence in different crystallographic directions. From a comparison of ion channeling in combination with H-1(N-15, alpha gamma)C-12 nuclear reaction analysis and Monte Carlo simulations we show that hydrogen is located in octahedral z sites and quantify its vibrational amplitude of 0.2 angstrom.
|
|
| 23. |
- Lumetzberger, Julia, et al.
(författare)
-
Influence of structure and cation distribution on magnetic anisotropy and damping in Zn/Al doped nickel ferrites
- 2020
-
Ingår i: Physical Review B. - : American Physical Society (APS). - 2469-9950 .- 2469-9969. ; 102:5
-
Tidskriftsartikel (refereegranskat)abstract
- An in-depth analysis of Zn/Al-doped nickel ferrites grown by reactive magnetron sputtering is relevant due to their promising characteristics for applications in spintronics. The material is insulating and ferromagnetic at room temperature with an additional low magnetic damping. By studying the complex interplay between strain and cation distribution their impact on the magnetic properties, i.e., anisotropy, damping, and g-factor is unravelled. In particular, a strong influence of the lattice site occupation of Ni-Td(2+) and cation coordination of Fe-Oh(2+), on the intrinsic damping is found. Furthermore, the critical role of the incorporation of Zn2+ and Al3+ is evidenced by comparison to a sample of altered composition. Specifically, the dopant Zn2+ is evidenced as a tuning factor for Ni-Td(2+) and therefore unquenched orbital moment directly controlling the g-factor. A strain-independent reduction of the magnetic anisotropy and damping by adapting the cation distribution is demonstrated.
|
|
| 24. |
- Mathayan, Vairavel, et al.
(författare)
-
Assessing the potential of ion beam analytical techniques for depth profiling Li in thin film Li ion batteries
- 2021
-
Ingår i: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 130:12
-
Tidskriftsartikel (refereegranskat)abstract
- Depth resolution and probing depth for Li in lithium thin film batteries achievable using different ion beam analytical techniques were investigated. Experiments using protons for nuclear reaction analysis, He ions for time-of-flight (TOF) energy elastic recoil detection analysis (ERDA) in transmission geometry, as well as He and Li ions for coincidence ERDA in transmission geometry are performed. Experimental results are compared in terms of the obtained Li concentration in the separator layer. In coincidence ERDA experiments, significant loss of Li-Li and He-Li coincidence counts was observed due to multiple scattering of recoiled/scattered particles in the battery sample. The ideal achievable Li depth resolution was calculated for the ion beam techniques. A depth resolution of 750, 1030, 310, and 510 x 10(15) atoms/cm(2) could be achieved in the Nb2O5 cathode by nuclear reaction analysis (NRA) using 2 MeV H, TOF-ERDA using 8 MeV He, and coincidence ERDA using 8 MeV He and 8 MeV Li ions, respectively, upon optimization of the experimental setup. While a depth resolution of 120 x 10(15) ions/cm(2) could be achieved for Li by conventional TOF-ERDA using an solid-state detector energy detector and light primary ions such as O under gracing incidence, TOF-ERDA experiments are found to produce significantly higher beam damage in batteries than other techniques. The beam damage in NRA and coincidence ERDA as performed in this study is estimated to be of the order of 10(-4) dpa. (C)& nbsp;2021 Author(s).& nbsp; All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license(http://creativecommons.org/licenses/by/4.0/).
|
|
| 25. |
- Mathayan, Vairavel, et al.
(författare)
-
In-operando observation of Li depth distribution and Li transport in thin film Li ion batteries
- 2020
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 117:2
-
Tidskriftsartikel (refereegranskat)abstract
- A quantitative assessment of Li transport is decisive for Li ion battery research. Here, we demonstrate in situ and in-operando depth profiling of the Li-inventory in lithium thin film batteries. We employ non-destructive coincidence elastic recoil detection analysis using different projectile ions in the MeV range to simultaneously quantify the lithium depth distribution in the whole stack with resolution better than 50nm by simulations of experimental data. Experiments were performed while charging and discharging the stack. 5MeV Li-7 primary ions were employed to extract the Li depth distribution in an similar to 3.6 mu m thick Ti/LMO/LIPON/NbO/Ti thin film battery. To show the versatility of the approach, a coincidence experiment was also performed using 4MeV He ions for an similar to 3.4 mu m thick Ti/LMO/LIPON/NbO/Ti battery. Our results illustrate, for example, lithium accumulation in the 90nm thick NbO layer upon charging with +3V. We could also show the transport of large amounts of Li from the LMO/LIPON interface to the LIPON/NbO interface upon overcharging with +5V. Altogether, these experiments demonstrate the potential of the employed technique, enabling in-operando high resolution composition depth profiling of Li and other light elements (e.g., H, He, C, N, and O) in ultrathin all-solid state batteries.
|
|
| 26. |
- Moldarev, Dmitrii, et al.
(författare)
-
Environmental dependence of the photochromic effect of oxygen-containing rare-earth metal hydrides
- 2021
-
Ingår i: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 129:15
-
Tidskriftsartikel (refereegranskat)abstract
- We study the dependence of the photochromic effect on environment and triggering light. We demonstrate that the first darkening/bleaching cycle of freshly grown films is accompanied by a release of weakly bound hydrogen, most likely present at the grain boundaries. For consecutive photochromic cycles, we do not find further exchange of material with the environment. Moreover, we report bleaching kinetics dependent on the gas environment after darkening with light of energies below the optical bandgap of the film. For darkening with photon energies above the bandgap of the film, we report a linear relation between the degree of darkening and bleaching relaxation time irrespective of gas environment.
|
|
| 27. |
- Moldarev, Dmitrii, et al.
(författare)
-
Oxygen mobility in yttrium hydride films studied by isotopic labelling
- 2022
-
Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. ; 261, s. 01001-01001
-
Tidskriftsartikel (refereegranskat)abstract
- The photochromic properties of oxygen-containing yttrium hydride thin films are directly dependent on the oxygen concentration in the material. We use 16O/18O labelling to study oxidation of YH2 films. Oxygen penetrates the film through grain boundaries and intercolumnar voids oxidising the whole film thickness, without pronounced surface oxidation or self-passivation. Once oxidised, the mobility of oxygen in the films is low and no detectable changes in chemical composition of 18O-labeled YHO films is found under illumination.
|
|
| 28. |
- Moldarev, Dmitrii, et al.
(författare)
-
Yttrium oxyhydrides for photochromic applications : Correlating composition and optical response
- 2018
-
Ingår i: Physical Review Materials. - 2475-9953. ; 2:11
-
Tidskriftsartikel (refereegranskat)abstract
- It has been recently demonstrated that yttrium oxyhydride (YHO) films can exhibit reversible photochromic properties when exposed to illumination at ambient conditions. This switchable optical property enables their utilization in many technological applications, such as smart windows, sensors, goggles, and medical devices. However, how the composition of the films affects their optical properties is not fully clear and therefore demands an investigation. In this paper, the composition of YHO films manufactured by reactive magnetron sputtering under different conditions is deduced in a ternary diagram from time-of-flight elastic recoil detection analysis. The results suggest that stable compounds are formed with a specific chemical formula-YH2-delta O delta. In addition, optical and electrical properties of the films are investigated, and a correlation with their compositions is established. The corresponding photochromic response is found in a specific oxygen concentration range (0.45 < delta < 1.5) with maximum and minimum of magnitude on the lower and higher border, respectively.
|
|
| 29. |
- Moro, Marcos V., et al.
(författare)
-
Accurate high-resolution depth profiling of magnetron sputtered transition metal alloy films containing light species : A multi-method approach
- 2019
-
Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 686
-
Tidskriftsartikel (refereegranskat)abstract
- We present an assessment of a multi-method approach based on ion beam analysis to obtain high-resolution depth profiles of the total chemical composition of complex alloy systems. As a model system we employ an alloy based on several transition metals and containing light species. Samples have been investigated by a number of different ion-beam based techniques, i.e., Rutherford Backscattering Spectrometry, Particle-Induced X-ray Emission, Elastic Backscattering Spectrometry and Time-of-Flight/Energy Elastic Recoil Detection Analysis. Sets of spectra obtained from these different techniques were analyzed both independently and following an iterative and self-consistent approach yielding a more accurate depth profile of the sample, including both metallic heavy constituents (Cr, Fe and Ni) as well as the rather reactive light species (C, O) in the alloy. A quantitative comparison in terms of achievable precision and accuracy is made and the limitations of the single method approach are discussed for the different techniques. The multi-method approach is shown to yield significantly improved and accurate information on stoichiometry, depth distribution and thickness of the alloy with the improvements being decisive for a detailed correlation of composition to the material properties such as corrosion strength. The study also shows the increased relative importance of experimental statistics for the achievable accuracy in the multi-method approach.
|
|
| 30. |
- Moro, Marcos V., et al.
(författare)
-
Experimental electronic stopping cross section of transition metals for light ions : Systematics around the stopping maximum
- 2020
-
Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - : American Physical Society (APS). - 2469-9926 .- 2469-9934. ; 102:2
-
Tidskriftsartikel (refereegranskat)abstract
- Electronic stopping cross sections of different transition metals (Nb, Pd, Ta, and Pt) for light ions have been experimentally determined in a wide energy range. We performed relative measurements using different backscattering geometries for protons (from 50 to 5000 keV) and helium (from 80 to 10000 keV). Data are compared to values from the literature, as well as to the widely used semiempirical (SRIM) and modeling (DPASS) approaches. The magnitude and energy dependence of the deduced stopping power at energies around the Bragg peak, as well as the different trends observed within individual periods, are analyzed with respect to target atomic number and electronic structure. We also compare the observed magnitude of electronic stopping to several different theoretical approaches.
|
|
| 31. |
- Moro, Marcos V., et al.
(författare)
-
In-situ composition analysis of photochromic yttrium oxy-hydride thin films under light illumination
- 2019
-
Ingår i: Solar Energy Materials and Solar Cells. - : Elsevier BV. - 0927-0248 .- 1879-3398. ; 201
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, we investigate the chemical composition of a reactively sputtered photochromic YHxOy thin film by non-destructive ion beam-based techniques, i.e., Rutherford Backscattering Spectrometry, Particle-Induced X-Ray Emission, Time-of-Flight/Energy coincidence Elastic Recoil Detection Analysis and Elastic Backscattering Spectrometry. To enhance the accuracy of the analysis, the set of spectra was evaluated in an iterative self-consistent approach. This procedure resulted in high-resolution depth profiles of the chemical composition and revealed a thin oxygen-rich-layer on the surface, which apparently does not act as a self-passivation layer. In the film, the concentration of Y remains practically constant, whereas O replaces H during the oxidation process. In-situ light illumination was performed during the compositional analysis in a high vacuum setup. The results from these measurements demonstrate that, for these samples, the induced reversible photochromism is not linked to any detectable change in the bulk composition of the film and can thus take place even in a vacuum environment.
|
|
| 32. |
- Moro, Marcos V., et al.
(författare)
-
Photochromic Response of Encapsulated Oxygen-Containing Yttrium Hydride Thin Films
- 2021
-
Ingår i: Physica Status Solidi. Rapid Research Letters. - : John Wiley & Sons. - 1862-6254 .- 1862-6270. ; 15:6
-
Tidskriftsartikel (refereegranskat)abstract
- Photochromic oxygen-containing yttrium-hydride thin films are synthesized by argon magnetron sputtering on microscope slides. Some of them are encapsulated with a thin, transparent, and nonphotochromic diffusion-barrier layer of either Al2O3 or Si3N4. Ion-beam-based methods prove that these protective diffusion barriers are stable and free from pinholes, with thicknesses of only a few tens of nanometers. Optical spectrophotometry reveals that the photochromic response and relaxation time for both protected and unprotected samples are almost identical. Ageing effects in the unprotected films lead to degradation of the photochromic performance (self-delamination), whereas the photochromic response for the encapsulated films is stable. The results show that the environment does not play a decisive role for the photochromic process and the encapsulation of oxygen-containing rare-earth hydride films with transparent and nonorganic thin diffusion-barrier layers provides long-time stability of the films, mandatory for applications as photochromic coatings on, e.g., smart windows.
|
|
| 33. |
- Moro, Marcos V., et al.
(författare)
-
Photochromism in Isotopically Labeled Oxygen-Containing Yttrium-Hydride and Deuteride Thin-Film Systems
- 2022
-
Ingår i: Physica Status Solidi. Rapid Research Letters. - : John Wiley & Sons. - 1862-6254 .- 1862-6270. ; 16:4
-
Tidskriftsartikel (refereegranskat)abstract
- Photochromic mono- and bilayered thin films of oxygen-containing isotope-labeled yttrium-hydride (i.e., protium and deuterium) are synthesized via reactive Ar sputtering. Selected samples are encapsulated with transparent diffusion barriers. Combining depth-resolved nondestructive ion beam-based techniques for composition and optical spectrophotometry, material mobility in the samples during illumination and over time is investigated. The results reveal that deuteride thin films exhibit a strong photochromic response equivalent to hydrogenated systems. No evidence of long-distance light-induced hydrogen mobility or thermal diffusion is found. The findings thus show that photochromism is not connected to long-distance material transport. The observations for encapsulated samples also exclude direct material exchange with the environment and any environmental influence on material mobility.
|
|
| 34. |
- Moro, Marcos V., et al.
(författare)
-
Stopping cross section of vanadium for H+ and He+ ions in a large energy interval deduced from backscattering spectra
- 2018
-
Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 424, s. 43-51
-
Tidskriftsartikel (refereegranskat)abstract
- We have experimentally determined electronic stopping cross sections of vanadium for 50-2750 keV protons and for 250-6000 keV He ions by relative measurements in backscattering geometry. To check the consistency of the employed procedure we investigate how to define adequate reference stopping cross section data and chose different reference materials. To proof consistency of different reference data sets, an intercomparison is performed to test the reliability of the evaluation procedure for a wide range of energies. This process yielded consistent results. The resulting stopping cross section data for V are compared to values from the IAEA database, to the most commonly employed semi-empirical program SRIM, and to calculations according to CasP. For helium, our results show a significant deviation of up to 10% with respect to literature and to SRIM, but are in very good agreement with the CasP predictions, in particular when charge-exchange processes are included in the model.
|
|
| 35. |
- Shu, Rui, 1990-, et al.
(författare)
-
Effect of nitrogen content on microstructure and corrosion resistance of sputter-deposited multicomponent (TiNbZrTa)Nx films
- 2020
-
Ingår i: Surface & Coatings Technology. - LAUSANNE, SWITZERLAND : Elsevier BV. - 0257-8972 .- 1879-3347. ; 404
-
Tidskriftsartikel (refereegranskat)abstract
- Multicomponent (TiNbZrTa)Nx films were deposited on Si(100) substrates at room temperature using magnetron sputtering with a nitrogen flow ratio fN [fN = N2/(Ar + N2)], which was varied from 0 to 30.8%. The nitrogen content in the films varied between 0 and 45.2 at.%, i.e., x = 0 to 0.83. The microstructure was characterized by X-ray diffraction and electron microscopy. The metallic TiNbZrTa film comprised a dominant bcc solid-solution phase, whereas a single NaCl-type face-centred cubic structure was observed in all nitrogen-containing films (TiNbZrTa)Nx. The mechanical, electrical, and electrochemical properties of these films varied with nitrogen content. The maximum hardness was achieved at 22.1 ± 0.3 GPa when N = 43.0 at.%. The resistivities increased from 95 to 424 μΩcm with increasing nitrogen content. A detailed study of the variation of morphology and chemical bonding with nitrogen content was performed and the corrosion resistance of the TiNbZrTa nitride films was explored in 0.1 M H2SO4. While all the films had excellent corrosion resistances at potentials up to 2.0 V vs. Ag/AgCl, the metallic film and the films with low nitrogen contents (x < 0.60) exhibited an almost stable current plateau up to 4.0 V vs. Ag/AgCl. For the films with higher nitrogen contents (x ≥ 0.68), the current plateau was retained up to 2.0 V vs. Ag/AgCl, above which a higher nitrogen content resulted in a higher current. The decrease in the corrosion resistance at these high potentials indicate the presence of a potential-dependent activation effect resulting in an increased oxidation rate of the nitrides (present under the passive oxide film) yielding a release of nitrogen from the films. TEM results indicate that the oxide layer formed after this corrosion measurement was thick and porous for the film with x = 0.76, in very good agreement with the increased corrosion rate for this film. The results demonstrate that an increased nitrogen content in (TiNbZrTa)Nx system improves their mechanical properties with retained high corrosion resistance at potentials up to 2.0 V vs. Ag/AgCl in 0.1 M H2SO4. At even higher potentials, however, the corrosion resistance decreases with increasing nitrogen concentration for films with sufficiently high nitrogen contents (i.e. x ≥ 0.68).
|
|
