| 1. |
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| 2. |
- Alling, Björn, et al.
(author)
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Theoretical investigation of cubic B1-like and corundum (Cr1−xAlx)2O3 solid solutions
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Other publication (other academic/artistic)abstract
- First-principles calculations are employed to investigate the stability and properties of cubic rock-salt like (Cr1−xAlx)2O3 solid solutions, stabilized by metal site vacancies as recently reported experimentally. It is demonstrated that the metal site vacancies can indeed be ordered in a way that gives rise to a favorable coordination of all O atoms in the lattice. B1-like structures with ordered and disordered metal site vacancies are studied for (Cr0.5Al0.5)2O3 and found to a have cubic lattice spacing close to the values reported experimentally, in contrast to fluorite-like and perovskite structures. The obtained B1-like structures are higher in energy than corundum solid solutions for all compositions, but with an energy offset per atom similar to other metastable systems possible to synthesize with physical vapor deposition techniques. The obtained electronic structures show that the B1-like systems are semiconducting although with smaller band gaps than the corundum structure.
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| 3. |
- Bakoglidis, Konstantinos D., et al.
(author)
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Nanotribological properties of wear resistant a-CNx thin films deposited by mid-frequency magnetron sputtering
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Other publication (other academic/artistic)abstract
- The nanotribological properties of amorphous carbon nitride (a-CNx) thin films deposited with mid-frequency magnetron sputtering (MFMS) were investigated at the nanoscale using an in-situ technique in a Hysitron Triboindenter TI 950. The friction coefficient, wear rate, track roughness, and the track profiles were recorded as a function of the number of linear reciprocal cycles, revealing the manner that the nanotribological and surface properties change during the wear test. The surface composition of the films was evaluated by x-ray photoelectron spectroscopy (XPS). The friction coefficient ranges between 0.05 – 0.07, while the wear coefficient ranges from 9.4 x 10-8 up to 1.5 x 10-4 mm3/Nm. Debris particles and surface modifications characterize the friction and lubrication behavior in the track. The friction and main lubrication mechanism on the modified surface changes after the removal of debris particles, while this change appears at different cycle for each CNx film depending on the substrate bias voltage. Films grown at higher bias are modified earlier than films grown at lower bias. The wear behavior can be divided into two, track roughnessdependent, regimes; (1) films with track roughness > 1 nm showed wear with obvious tracks and (2) the films with roughness < 1 nm showed negative wear at the nanometer scale with a volume of material projected in the area of the wear track. This material volume is believed to be result of a surface modification, where the molar volume of the modified surface is larger than the molar volume of the surface before the wear test.
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| 4. |
- Broitman, E., et al.
(author)
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Structural, electrical, and optical properties of diamondlike carbon films deposited by dc magnetron sputtering
- 2003
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In: Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films. - : American Vacuum Society. - 0734-2101 .- 1520-8559.
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Other publication (other academic/artistic)abstract
- The electrical and optical properties of diamondlike carbon films deposited by direct current magnetron sputtering on Si substrates at room temperature have been measured as a function of the ion energy (Eion) and ion-to-carbon flux (Jion/JC). The results show that, in the ranges of 5 eV⩽Eion⩽85 eV and 1.1⩽Jion/JC⩽6.8, the presence of defective graphite formed by subplanted C and Ar atoms, voids, and the surface roughness, are the dominant influences on the resistivity and optical absorption
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| 5. |
- Engberg, David L. J., et al.
(author)
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Solid Solution and Segregation Effects in Arc-Deposited Ti1-xSixN Thin Films Resolved on the nanometer scale by 15N Isotopic Substitution in AtomP robe Tomography
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Other publication (other academic/artistic)abstract
- Nanostructured TiSiN is an important material in wear--‐resistant coatings for extending the lifetime of cutting tools. Yet, the understanding regarding the structure, phase composition, and bonding on the detailed nanometer scale, which determines the properties of TiSiN, is lacking. This limits our understanding of the growth phenomena and eventually a larger exploitation of the material. By substituting natN2 with 15N2 during reactive arc deposition of TiSiN thin films, atom probe tomography (APT) gives elemental sensitivity and sub-nanometer resolution, a finer scale than what can be obtained by commonly employed energy dispersive electron spectroscopy in scanning transmission electron microscopy. Using a combination of analytical transmission electron microscopy and APT we show that arc-deposited Ti0.92Si0.0815N and Ti0.81Si0.1915N exhibit Si segregation on the nanometer scale in the alloy films. APT composition maps and proximity histograms from domains with higher than average Ti content show that the TiN domains contain at least ~2 at. % Si for Ti0.92Si0.08N and ~5 at. % Si for Ti0.81Si0.19N, thus confirming the formation of solid solutions. The formation of relatively pure SiNy domains in the Ti0.81Si0.19N films is tied to pockets between microstructured, columnar features in the film. Finer SiNy enrichments seen in APT possibly correspond to tissue layers around TiN crystallites, thus effectively hindering growth of TiN crystallites, causing TiN renucleation and thus explaining the featherlike nanostructure within the columns of these films. For the stoichiometry of the TiN phase, we establish a global under stoichiometry, in accordance with the tendency for SiNy films to have tetrahedral bonding coordination towards a nominal Si3N4 composition.
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| 6. |
- Eriksson, Anders, et al.
(author)
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Nanocolumnar Epitaxial Ti1-xSixN (0 ≤ x ≤ 0.18) Thin Films Grown by Dual Reactive Magnetron Sputtering on MgO (001), (011), and (111) Substrates
- 2012
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Other publication (other academic/artistic)abstract
- Ti1-xSixNy thin films and multilayers have been grown on single-crystal TiN-templated MgO (001), (011), and (111) substrates kept at 550 °C. Elemental Ti and Si targets were used in UVH reactive dual magnetron sputtering in a mixed Ar/N2 discharge. Composition analysis by time-of-flight energy elastic recoil detection analysis show that the films are close to stoichiometric (0.95 ≤ y ≤ 1.00) with respect to TiN over the wide range of Si concentrations 0 ≤ x ≤ 0.22. High-resolution transmission electron microscopy (TEM) combined with scanning TEM and energy dispersive Xray analysis show that all films grow epitaxially for x ≤ 0.18 and that as much as every fifth Ti atom can be replaced by Si (~10 at.%) in Ti1-xSixN(001). For the (011) and (111)-oriented films, however, only 1-2 at.% Si substitutes for Ti. Instead, Si segregates to form crystalline-to-amorphous SiNz (z ≈ 1) tissue phases, which promote the formation of epitaxial TiN nanocolumns. The nanocolumns have preferred {110} interfaces and {200} top facets and grow several hundreds of nm in length.
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| 7. |
- Fager, Hanna, et al.
(author)
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Growth and Properties of Amorphous Hf1−x−yAlxSiyN (0≤x≤0.2; 0≤y≤0.2) and a-Hf0.6Al0.2Si0.2N/nc-HfN Multilayers by DC Reactive Magnetron Sputtering from a Single Hf0.60Al0.20Si0.20 Target
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Other publication (other academic/artistic)abstract
- Amorphous (a) and nanocrystalline (nc) Hf1−x−yAlxSiyN and multilayer a-Hf0.6Al0.2Si0.2N/nc-HfN films are grown on Si(001) at temperatures Ts = 100-450 ◦C using ultrahigh vacuum magnetically-unbalanced reactive magnetron sputtering from a single Hf0.60Al0.20Si0.20 target in a 5%-N2/Ar atmosphere at a total pressure of 20 mTorr (2.67 Pa). The composition and nanostructure of Hf1−x−yAlxSiyN is controlled during growth by independently varying the ion energy (Ei) and the ion-to-metal flux ratio (Ji/JMe) incident at the film surface. With Ji/JMe = 8, the composition and nanostructure of the films ranges from x-ray amorphous with 1-x-y = 0.60 at Ei = 15 eV, to an amorphous matrix with encapsulated nanocrystals with 1-x-y = 0.66-0.84 at Ei = 25-35 eV, to nanocrystalline with 1-x-y = 0.96-1.00 at Ei = 45-65 eV. Varying Ji/JMe with Ei = 13 eV yields amorphous alloy films at Ts = 100 ◦C. a-Hf0.6Al0.6Si0.6N/nc-HfN multilayers with periods Λ = 2-20 nm exhibit enhanced fracture toughness compared to polycrystalline VN, TiN, and Ti0.5Al0.5N reference samples; multilayer hardness values increase monotonically from 20 GPa with Λ = 20 nm to 27 GPa with Λ = 2 nm.
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| 8. |
- Fager, Hanna, et al.
(author)
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Hf-Al-Si-N multilayers deposited by reactive magnetron sputtering from a single Hf0.6Al0.2Si0.2 target using high-flux, low-energy modulated substrate bias : film growth and properties
- 2014
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Other publication (other academic/artistic)abstract
- Hf1−x−yAlxSiyN (0≤x≤0.14, 0≤y≤0.13) single layers and multilayer films are grown on Si(001) at a substrate temperature Ts=250 °C using ultrahigh vacuum magnetically-unbalanced reactive magnetron sputtering from a single Hf0.6Al0.2Si0.2 target in a 5%-N2/Ar atmosphere at a total pressure of 20 mTorr (2.67 Pa). The composition and nanostructure of Hf1−x−yAlxSiyN is controlled during growth by varying the ion energy (Ei) of the ions incident at the film surface, keeping the ion-to-metal flux ratio (Ji/JMe) constant at 8. By sequentially switching Ei between 10 and 40 eV, Hf0.77Al0.10Si0.13N/Hf0.78Al0.14Si0.08N multilayers with bilayer periods Λ = 2-20 nm are grown, in which the Si2p bonding state changes from predominantly Si-Si bonds for films grown at Ei = 10 eV, to mainly Si-N bonds at Ei = 40 eV. Multilayer hardness values increase monotonically from 20 GPa with Λ = 20 nm to 27 GPa with Λ = 2 nm, while multilayer fracture toughness increases with increasing Λ. Multilayers with Λ = 10 nm have the optimized property combination of being bothrelatively hard, H∼24 GPa, and fracture tough.
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| 9. |
- Fager, Hanna, et al.
(author)
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Reactive DC magnetron sputtering of amorphous (Ti0.25B0.75)1−xSixNy thin films from TiB2 and Si targets
- 2014
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Other publication (other academic/artistic)abstract
- (Ti0.25B0.75)1−xSixNy, 0≤x≤0.89, 0.9≤y≤1.25, thin films were reactively grown on Si(001) substrates by dc magnetron sputtering from compound TiB2 and elemental Si targets. The films can be grown in a fully electron-diffraction amorphous state with x>0.46, as evidenced by XRD and HR-TEM investigations. With x=0, BN form onion-like sheets surrounding TiNnanograins. Substrate temperatures, Ts=100-600 ◦C, has a minor effect of the film structure and properties, due to limited surface diffusion.Ion-assisted growth with substrate bias voltages, Vb, between -50 V and -200 V, favors densification of amorphous structures over nanocrystalline formation, and improves mechanical properties. A maximum hardness value of 26.8±0.7 GPa is found for an amorphous (Ti0.25B0.75)0.39Si0.61N1.15 film grown with substrate temperature Ts=400 °C and substrate bias voltage Vb=-100 V.
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| 10. |
- Fallqvist, Amie, et al.
(author)
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Evidence for B1-cubic SiNx by Aberration-Corrected Analytical STEM
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Other publication (other academic/artistic)abstract
- The crystal structure of epitaxially stabilized SiNx layers on TiN(001) was investigated by analytical aberration corrected electron microscopy. Atomically resolved images of the structure, which were acquired by scanning transmission electron microscopy using high angle annular dark field and annular bright field detectors, are used to identify the B1-cubic structure of SiNx. To corroborate the acquired images, image simulations were performed using candidate structures. Complementary to imaging, spatially resolved electron energy loss spectroscopy of the epitaxial SiNx layers was performed to acquire the symmetry specific nitrogen near edge fine-structure. Finally, full potential calculations performed to determine the near edge structure from candidate crystal structures confirms the existence of B1-cubic SiNx.
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