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- Broitman, E., et al.
(författare)
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Carbon nitride films on orthopedic substrates
- 2000
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Ingår i: Diamond and related materials. - 0925-9635 .- 1879-0062. ; 9:12, s. 1984-1991
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Tidskriftsartikel (refereegranskat)abstract
- The mechanical and tribological properties of carbon nitride (CN(X)) films deposited on orthopedic substrates are presented. CN(X) films were prepared by d.c. reactive magnetron sputtering from a graphite target in N2/Ar plasma. Films were grown on Ni and ZrO2 substrates to a thickness of ~1 µm at a total pressure of 3 mtorr and a substrate temperature of 250°C. High-resolution transmission electron microscopy (HRTEM) shows dense and homogeneous films, with 'fullerene-like' micro-structures consisting of curved, frequently intersecting, and highly in-plane oriented basal lattice planes. Nanoindentation measurements revealed a change in the mechanical properties of films treated with three different biological solutions. Spectroscopic analysis confirmed a change in the chemical structure of the treated films. The friction coefficients of CN(X) films against high speed steel (HSS), ZrO2 and Ultra-High Molecular Weight Polyethylene (UHMWPE) balls were evaluated by ball-on-disk tests in dry and lubricated conditions. In the case of dry sliding against a HSS ball, the steady state friction coefficient values are 0.22 for the film on the Ti substrate and 0.26 for the film on the ZrO2 substrate. The friction coefficients under human serum lubrication conditions were below 0.18 for the ZrO2 and UHMWPE balls. An increase in wettability of human plasma on CN(X) films was observed compared to the orthopedic surfaces, which could enhance the retention of synovial fluid on those surfaces, improving the lubrication of the bearings of total joint arthroplasty components during function. (C) 2000 Elsevier Science B.V. All rights reserved.The mechanical and tribological properties of carbon nitride (CNX) films deposited on orthopedic substrates are presented. CNX films were prepared by d.c. reactive magnetron sputtering from a graphite target in N2/Ar plasma. Films were grown on Ni and ZrO2 substrates to a thickness of approximately 1 µm at a total pressure of 3 mtorr and a substrate temperature of 250 °C. High-resolution transmission electron microscopy (HRTEM) shows dense and homogeneous films, with `fullerene-like' microstructures consisting of curved, frequently intersecting, and highly in-plane oriented basal lattice planes. Nanoindentation measurements revealed a change in the mechanical properties of films treated with three different biological solutions. Spectroscopic analysis confirmed a change in the chemical structure of the treated films. The friction coefficients of CNX films against high speed steel (HSS), ZrO2 and Ultra-High Molecular Weight Polyethylene (UHMWPE) balls were evaluated by ball-on-disk tests in dry and lubricated conditions. In the case of dry sliding against a HSS ball, the steady state friction coefficient values are 0.22 for the film on the Ti substrate and 0.26 for the film on the ZrO2 substrate. The friction coefficients under human serum lubrication conditions were below 0.18 for the ZrO2 and UHMWPE balls. An increase in wettability of human plasma on CNX films was observed compared to the orthopedic surfaces, which could enhance the retention of synovial fluid on those surfaces, improving the lubrication of the bearings of total joint arthroplasty components during function.
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- Gago, R, et al.
(författare)
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Transition from amorphous boron carbide to hexagonal boron carbon nitride thin films induced by nitrogen ion assistance
- 2002
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 92:9, s. 5177-5182
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Tidskriftsartikel (refereegranskat)abstract
- Boron carbon nitride films (BCN) were grown by B4C evaporation under concurrent N-2 ion beam assistance. The films were characterized by x-ray absorption near-edge spectroscopy, infrared and Raman spectroscopies, and high-resolution transmission electron microscopy. The bonding structure and film composition correlate with the momentum transfer per incoming atom during deposition. As the momentum transfer is increased, the film structure evolves from an amorphous boron carbide network towards a hexagonal ternary compound (h-BCN) with standing basal planes. The growth of h-BCN takes place for momentum transfer in the window between 80 and 250 (eVxamu)(1/2). The characteristic vibrational features of the h-BCN compounds have also been studied. Finally, the solubility limit of carbon in the hexagonal BN structure, under the working conditions of this article, is found to be similar to15 at. %. (C) 2002 American Institute of Physics.
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- Horvath, ZJ, et al.
(författare)
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Electrical peculiarities in Al/Si/Ge/... /Ge/Si and Al/SiGe/Si structures
- 2002
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Ingår i: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 190:1-4, s. 403-407
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Tidskriftsartikel (refereegranskat)abstract
- The current-voltage (I-V) and capacitance-voltage (C-V) behaviour of different Si/Ge multilayers and SiGe single layers prepared on p-type Si substrates by magnetron sputtering and annealing, has been studied in the temperature rang, of 80-320 K by using Al Schottky contacts as test structures. Although a significant influence of the microstructure of the Si/Ge multilayers and SiGe layers was obtained on the electrical behaviour of the structures, the structures exhibited similar specific features. (C) 2002 Elsevier Science B.V. All rights reserved.
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- Hultman, Lars, et al.
(författare)
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Cross-linked nano-onions of carbon nitride in the solid phase : Existence of a novel C48N12 aza-fullerene
- 2001
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 87:22, s. art. no.-225503
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Tidskriftsartikel (refereegranskat)abstract
- We report a new fullerenelike material consisting of cross-linked nano-onions of C and N. Growth of the onion shells takes place atom by atom on a substrate surface and yields thin solid films during magnetron sputter deposition. Electron microscopy and energy loss spectroscopy show that the core shell contains up to 20 at. % N corresponding to C48N12 aza-fullerene composition. Nanoindentation of this nanostructured material gives high resilience with hardness 7 GPa, Young's modulus 37 GPa, and complete elastic recovery after loading with 0.5 mN to a depth of 75 nm. Total energy calculations show the stability Of C60-2nN2n aza-fullerenes and suggest the existence of a novel C48N12 molecule.
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- Music, Denis, et al.
(författare)
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Quantum design and synthesis of a boron-oxygen-yttrium phase
- 2003
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 82:24, s. 4286-4288
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Tidskriftsartikel (refereegranskat)abstract
- A study was performed on quantum design and synthesis of a boron-oxygen-yttrium (BOY) phase. The calculations predicted that the BOY phase was 0.36 eV/atom more stable than crystalline BO0.17. The results showed that films with Y/B ratios ranging from 0.10 to 0.32, as determined via elastic recoil detection analysis, were grown over wide range of temperatures (300-600°C) and found to withstand 1000°C.
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- Neidhardt, Jörg, et al.
(författare)
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Correlated high resolution transmission electron microscopy and X-ray photoelectron spectroscopy studies of structured CNx (0 < x < 0.25) thin solid films
- 2004
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Ingår i: Carbon. - : Elsevier BV. - 0008-6223 .- 1873-3891. ; 42:Dec-13, s. 2729-2734
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Tidskriftsartikel (refereegranskat)abstract
- Structured carbon nitride (CNx), thin solid films, also known as fullerene-like, consist of, upon nitrogen substitution, bent and cross-linked graphene planes. They were synthesized by unbalanced reactive magnetron sputtering and analyzed by high-resolution transmission electron microscopy (HRTEM) in combination with X-ray photoelectron spectroscopy (XPS). The microstructure evolution in terms of plane alignment, extension and cross-linking can be controlled by adjusting the synthesis conditions, such as growth temperature, N-2 fraction in the discharge gas and ion energy. HRTEM on plan-view samples was used to examine the structural changes depending on growth temperature and N-2 fraction. The problem of projection artifacts for imaging the structural features was partially overcome by selected area electron diffraction analysis, where it is shown that diffraction corresponding to 3.5 Angstrom is associated with the formation of structured CNx. The incorporation of N is crucial for the evolution of heavily bent and frequently cross-linked basal planes, since it triggers pentagon formation and cross-linking at much lower energies compared to pure carbon films. Therefore, the two spectral features in the nitrogen Is core electron spectra as examined by XPS were correlated to the microstructure evolution. (C) 2004 Elsevier Ltd. All rights reserved.
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