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- Bakhit, Babak, 1983-, et al.
(författare)
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Systematic compositional analysis of sputter-deposited boron-containing thin films
- 2021
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Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : American Vacuum Society. - 0734-2101 .- 1520-8559. ; 39:6
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Tidskriftsartikel (refereegranskat)abstract
- Boron-containing materials exhibit a unique combination of ceramic and metallic properties that are sensitively dependent on their given chemical bonding and elemental compositions. However, determining the composition, let alone bonding, with sufficient accuracy is cumbersome with respect to boron, being a light element that bonds in various coordinations. Here, we report on the comprehensive compositional analysis of transition-metal diboride (TMBx) thin films (TM = Ti, Zr, and Hf) by energy-dispersive x-ray spectroscopy (EDX), x-ray photoelectron spectroscopy (XPS), time-of-flight elastic recoil detection analysis (ToF-ERDA), Rutherford backscattering spectrometry (RBS), and nuclear reaction analysis (NRA). The films are grown on Si and C substrates by dc magnetron sputtering from stoichiometric TMB2 targets and have hexagonal AlB2-type columnar structures. EDX considerably overestimates B/TM ratios, x, compared to the other techniques, particularly for ZrBx. The B concentrations obtained by XPS strongly depend on the energy of Ar+ ions used for removing surface oxides and contaminants prior to analyses and are more reliable for 0.5 keV Ar+. ToF-ERDA, RBS, and NRA yield consistent compositions in TiBx. They also prove TiBx and ZrBx films to be homogeneous with comparable B/TM ratios for each film. However, ToF-ERDA, employing a 36-MeV 127I8+ beam, exhibits challenges in depth resolution and quantification of HfBx due to plural and multiple scattering and associated energy loss straggling effects. Compared to ToF-ERDA, RBS (for the film grown on C substrates) and NRA provide more reliable B/Hf ratios. Overall, a combination of methods is recommended for accurately pinpointing the compositions of borides that contain heavy transition metals.
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| 2. |
- Glechner, T., et al.
(författare)
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Influence of the non-metal species on the oxidation kinetics of Hf, HfN, HfC, and HfB2 coatings
- 2021
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Ingår i: Materials & design. - : Elsevier. - 0264-1275 .- 1873-4197. ; 211
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Tidskriftsartikel (refereegranskat)abstract
- The influence of the non-metal species on the oxidation resistance of transition metal ceramic based thin films is still unclear. For this purpose, we thoroughly investigated the oxide scale formation of a metal (Hf), carbide (HFC0.96), nitride (HfB1.5), and boride (HfB2.3) coating grown by physical vapor deposition. The non-metal species decisively affect the onset temperature of oxidation, ranging between 550 degrees C for HfC0.96 to 840 degrees C for HfN1.5. HfB2.3 and HfN1.5 obtain the slowest oxide scale kinetic following a parabolic law with k(p) values of 4.97.10(-10) and 5.66.10(-11) kg(2) m(-4) s(-1) at 840 degrees C, respectively. A characteristic feature for the oxide scale on Hf coatings, is a columnar morphology and a substantial oxygen inward diffusion. HfC0.96 reveals an ineffective oxycarbide based scale, whereas HfN(1.5 )features a scale with globular HfO2 grains. HfB(2.3 )exhibits a layered scale with a porous boron rich region on top, followed by a highly dense and crystalline HfO2 beneath. Furthermore, HfB(2.3 )presents a hardness of 47.7 +/- 2.7 GPa next to an exceptional low inward diffusion of oxygen during oxidation. This study showcases the strong influence of the non-metallic bonding partner despite the same metallic basis, as well as the huge potential for HfB2 based coatings also for oxidative environments.
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| 3. |
- Pitthan, Eduardo, et al.
(författare)
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Assessing boron quantification and depth profiling of different boride materials using ion beams
- 2021
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Ingår i: Surface & Coatings Technology. - : Elsevier. - 0257-8972 .- 1879-3347. ; 417
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Tidskriftsartikel (refereegranskat)abstract
- We assessed the capability to quantify and depth profile boron in different materials by a number of ion beam-based techniques. Specifically, the depth resolution, probing depth, film homogeneity, and detection limit for boron using particle-particle nuclear reaction analysis (resonant and non-resonant mode), elastic backscattering spectrometry, and time-of-flight elastic recoil detection analysis using heavy primary ions were evaluated. Samples consisted of high and low-Z materials implanted by B-11(+) at different energies and fluences, Au/BN structures as well as bulk boride targets. Advantages and limitations for the individual techniques for the different sample types are discussed. As an example, while ToF-ERDA allows to efficiently depth profile B-10 and B-11 individually, limitations in probing depth and depth resolution, as well as quantification are apparent in particular for target materials containing high-Z species. While EBS presents large probing depth (similar to 14 mu m), the best detection limit (similar to 0.1 x 10(15)/cm(2)) is obtained from resonant-NRA.
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