| 1. |
- Elhag, Sami, et al.
(författare)
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Low-temperature growth of polyethylene glycol-doped BiZn2VO6 nanocompounds with enhanced photoelectrochemical properties
- 2017
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Ingår i: Journal of Materials Chemistry A. - Cambridge : Royal Society of Chemistry. - 2050-7488. ; 5:3, s. 1112-1119
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate scalable, low-cost and low-temperature (<100 °C) aqueous chemical growth of bismuth–zinc vanadate (BiZn2VO6) nanocompounds by BiVO4 growth on ZnO nanobelts (NBs). The nanocompounds were further doped with polyethylene glycol (PEG) to tune the electronic structure of the materials, as a means to lower the charge carrier recombination rate. The chemical composition, morphology, and detailed nanostructure of the BiZn2VO6 nanocompounds were characterized. They exhibit rice-like morphology, are highly dense on the substrate and possess a good crystalline quality. Photoelectrochemical characterization in 0.1 M lithium perchlorate in carbonate propylene shows that BiZn2VO6 nanocompounds are highly suitable as anodes for solar-driven photoelectrochemical applications, providing significantly better performance than with only ZnO NBs. This performance could be attributed to the heterogeneous catalysis effect at nanocompound and ZnO NB interfaces, which have enhanced the electron transfer process on the electrode surface. Furthermore, the charge collection efficiency could be significantly improved through PEG doping of nanocompounds. The photocurrent density of PEG-doped BiZn2VO6 nanocompounds reached values of 2 mA cm−2 at 1.23 V (vs. Ag/AgCl), over 60% larger than that of undoped BiZn2VO6 nanocompounds. Photoluminescence emission experiments confirmed that PEG plays a crucial role in lowering the charge carrier recombination rate. The presented BiZn2VO6 nanocompounds are shown to provide highly competitive performance compared with other state-of-the art photoelectrodes.
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| 2. |
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| 3. |
- Abbasi, Mazhar Ali, et al.
(författare)
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Decoration of ZnO nanorods with coral reefs like NiO nanostructures by the hydrothermal growth method and their luminescence study
- 2014
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Ingår i: Materials. - : MDPI. - 1996-1944. ; 7:1, s. 430-440
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Tidskriftsartikel (refereegranskat)abstract
- Composite nanostructures of coral reefs like p-type NiO on n-type ZnO nanorods have been decorate on fluorine-doped tin oxide glass substrates by the hydrothermal growth. Structural characterization was performed by field emission scanning electron microscopy, high-resolution transmission electron microscopy and X-ray diffraction techniques. This investigation has shown that the adopted synthesis has led to high crystalline quality nanostructures. Morphological study shows that the coral reefs like nanostructures are densely packed on the ZnO nanorods. Cathodoluminescence (CL) spectra for the synthesized composite nanostructures were dominated by a near band gap emission at 380 nm and by a broad interstitial defect related luminescence centered at ~630 nm. Spatially resolved CL images reveal that the luminescence originates mainly from the ZnO nanorods.
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| 4. |
- Abrikosov, Igor, et al.
(författare)
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Phase Stability and Elasticity of TiAlN
- 2011
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Ingår i: Materials. - : MDPI. - 1996-1944. ; 4:9, s. 1599-1618
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Tidskriftsartikel (refereegranskat)abstract
- We review results of recent combined theoretical and experimental studies of Ti1−xAlxN, an archetypical alloy system material for hard-coating applications. Theoretical simulations of lattice parameters, mixing enthalpies, and elastic properties are presented. Calculated phase diagrams at ambient pressure, as well as at pressure of 10 GPa, show a wide miscibility gap and broad region of compositions and temperatures where the spinodal decomposition takes place. The strong dependence of the elastic properties and sound wave anisotropy on the Al-content offers detailed understanding of the spinodal decomposition and age hardening in Ti1−xAlxN alloy films and multilayers. TiAlN/TiN multilayers can further improve the hardness and thermal stability compared to TiAlN since they offer means to influence the kinetics of the favorable spinodal decomposition and suppress the detrimental transformation to w-AlN. Here, we show that a 100 degree improvement in terms of w-AlN suppression can be achieved, which is of importance when the coating is used as a protective coating on metal cutting inserts.
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| 5. |
- Alling, Björn, et al.
(författare)
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Pressure enhancement of the isostructural cubic decomposition in Ti1−xAlxN
- 2009
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 95:181906
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Tidskriftsartikel (refereegranskat)abstract
- The influence of pressure on the phase stabilities of Ti1−xAlxN solid solutions has been studied using first principles calculations. We find that the application of hydrostatic pressure enhances the tendency for isostructural decomposition, including spinodal decomposition. The effect originates in the gradual pressure stabilization of cubic AlN with respect to the wurtzite structure and an increased isostructural cubic mixing enthalpy with increased pressure. The influence is sufficiently strong in the composition-temperature interval corresponding to a shoulder of the spinodal line that it could impact the stability of the material at pressures achievable in the tool-work piece contact during cutting operations
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| 6. |
- Almer, Jonathan, et al.
(författare)
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Microstructural evolution during tempering of arc-evaporated Cr-N coatings
- 2000
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Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : American Vacuum Society. - 0734-2101 .- 1520-8559. ; 18:1, s. 121-130
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Tidskriftsartikel (refereegranskat)abstract
- Cr-N coatings were arc-deposited at 50 and 300 V. The changes in the coating microstructure and phase content during tempering were monitored. As a result, the phase stability and activation energies for defect diffusion were determined as a function of ion energy.
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| 7. |
- Amini, Shahram, et al.
(författare)
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On the Stability of Mg Nanograins to Coarsening after Repeated Melting
- 2009
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Ingår i: NANO LETTERS. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 9:8, s. 3082-3086
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Tidskriftsartikel (refereegranskat)abstract
- Herein we report on the extraordinary thermal stability of similar to 35 nm Mg-nanograins that constitute the matrix of a Ti2AlC-Mg composite that has previously been shown to have excellent mechanical properties. The microstructure is so stable that heating the composite three times to 700 degrees C, which is 50 degrees C over the melting point of Mg, not only resulted in the repeated melting of the Mg, but surprisingly and within the resolution of our differential scanning calorimeter, did not lead to any coarsening. The reduction in the Mg melting point due to the nanograins was similar to 50 degrees C. X-ray diffraction and neutron spectroscopy results suggest that thin, amorphous, and/or poorly crystallized rutile, anatase, and/or magnesia layers separate the Mg nanograins and prevent them from coarsening. Clearly that layer is thin enough, and thus mechanically robust enough, to survive the melting and solidification stresses encountered during cycling. Annealing in hydrogen at 250 degrees C for 20 h, also did not seem to alter the grain size significantly.
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| 8. |
- Asif, Muhammad H., et al.
(författare)
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Growth and Structure of ZnO Nanorods on a Sub-Micrometer Glass Pipette and Their Application as Intracellular Potentiometric Selective Ion Sensors
- 2010
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Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 3, s. 4657-4667
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the growth and structure of ZnO nanorods on a sub-micrometer glass pipette and their application as an intracellular selective ion sensor. Highly oriented, vertical and aligned ZnO nanorods were grown on the tip of a borosilicate glass capillary (0.7 μm in diameter) by the low temperature aqueous chemical growth (ACG) technique. The relatively large surface-to-volume ratio of ZnO nanorods makes them attractive for electrochemical sensing. Transmission electron microscopy studies show that ZnO nanorods are single crystals and grow along the crystal’s c-axis. The ZnO nanorods were functionalized with a polymeric membrane for selective intracellular measurements of Na +. The membrane-coated ZnO nanorods exhibited a Na+-dependent electrochemical potential difference versus an Ag/AgCl reference micro-electrode within a wide concentration range from 0.5 mM to 100 mM. The fabrication of functionalized ZnO nanorods paves the way to sense a wide range of biochemical species at the intracellular level.
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| 9. |
- Bakoglidis, Konstantinos D., et al.
(författare)
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Low-temperature growth of low friction wear-resistant amorphous carbon nitride thin films by mid-frequency, high power impulse, and direct current magnetron sputtering
- 2015
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Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : American Vacuum Society. - 0734-2101 .- 1520-8559. ; 33:5
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Tidskriftsartikel (refereegranskat)abstract
- Amorphous carbon nitride (a-CNx) thin films were deposited on steel AISI52100 and Si(001) substrates using mid-frequency magnetron sputtering (MFMS) with an MF bias voltage, high power impulse magnetron sputtering (HiPIMS) with a synchronized HiPIMS bias voltage, and direct current magnetron sputtering (DCMS) with a DC bias voltage. The films were deposited at a low substrate temperature of 150 °C and a N2/Ar flow ratio of 0.16 at the total pressure of 400 mPa. The negative bias voltage (Vs) was varied from 20 V to 120 V in each of the three deposition modes. The microstructure of the films was characterized by high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED), while the film morphology was investigated by scanning electron microscopy (SEM). All films possessed amorphous microstructure with clearly developed columns extending throughout the entire film thickness. Layers grown with the lowest substrate bias of 20 V exhibited pronounced intercolumnar porosity, independent of the technique used. Voids closed and dense films formed at Vs ≥ 60 V, Vs ≥ 100 V and Vs = 120 V for MFMS, DCMS and HiPIMS, respectively. X-ray photoelectron spectroscopy (XPS) revealed that the nitrogen-to-carbon ratio, N/C, of the films ranged between 0.2 and 0.24. Elastic recoil detection analysis (ERDA) showed that Ar content varied between 0 and 0.8 at% and increases as a function of Vs for all deposition techniques. All films exhibited compressive residual stress, σ, which depends on the growth method; HiPIMS produces the least stressed films with stress between – 0.4 and – 1.2 GPa for all Vs values, while for CNx films deposited by MFMS σ = – 4.2 GPa. Nanoindentation showed a significant increase in film hardness and reduced elastic modulus with increasing Vs for all techniques. The harder films were produced by MFMS with hardness as high as 25 GPa. Low friction coefficients, between 0.05 and 0.06, were recorded for all films. Furthermore, CNx films produced by MFMS and DCMS at Vs = 100 V and 120 V presented a high wear resistance with wear coefficients of k ≤ 2.3 x 10-5 mm3/Nm.
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| 10. |
- Beheshti, Hooshang, et al.
(författare)
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Electronic supply chain management applications by Swedish SMEs
- 2007
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Ingår i: Enterprise Information Systems. - : Informa UK Limited. - 1751-7575 .- 1751-7583. ; 1:2, s. 255-268
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Tidskriftsartikel (refereegranskat)abstract
- The Internet has become an integral part of business activities of most corporations today. Electronic supply chain management (SCM) can improve the operational efficiency of the firm by streamlining processes between the company and its suppliers, business partners, and customers. This research explores the extent and the degree of Internet application in Swedish small- and medium-sized enterprises (SMEs). The analyses of the data show that the Swedish SMEs use the Internet in their supply chain activities to a large degree. The study establishes some differences between smaller and larger organizations as well as between manufacturing and service companies.
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| 11. |
- Beheshti, Hooshang M., et al.
(författare)
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Supply chain integration and firm performance : an empirical study of Swedish manufacturing firms
- 2014
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Ingår i: Competitiveness Review. - 1059-5422 .- 2051-3143. ; 24:1, s. 20-31
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Tidskriftsartikel (refereegranskat)abstract
- Purpose – This article aims to explore the impact of supply chain integration on the financial performance of Swedish manufacturing firms.Design/methodology/approach – The literature review provided the foundation for the development of the survey instrument and hypotheses for the study. In addition, the survey instrument was tested by the experts in the field and modified before it was sent to the managers in the survey group.Findings – The findings show that supply chain integration at any level is beneficial to the financial well being of the firm. Companies with total supply chain integration reported the highest level of financial performance.Research limitations/implications – Data were collected from Swedish manufacturing firms without regard to the size of the firm. The results show that supply chain integration is beneficial at any level.Practical implications – The findings will assist managers with decisions regarding supply chain integration and its role as a critical factor in improving the financial performance of manufacturing companies.Originality/value – Limited empirical studies have been conducted in this area, especially in Sweden. This study provides insight for manufacturing managers with regard to the importance of supply chain management and the competitive nature of business in the global market.
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| 12. |
- Benjamin, DJ, et al.
(författare)
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The Promises and Pitfalls of Genoeconomics*
- 2012
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Ingår i: Annual review of economics. - : Annual Reviews. - 1941-1383 .- 1941-1391. ; 4, s. 627-
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Tidskriftsartikel (refereegranskat)abstract
- This article reviews existing research at the intersection of genetics and economics, presents some new findings that illustrate the state of genoeconomics research, and surveys the prospects of this emerging field. Twin studies suggest that economic outcomes and preferences, once corrected for measurement error, appear to be about as heritable as many medical conditions and personality traits. Consistent with this pattern, we present new evidence on the heritability of permanent income and wealth. Turning to genetic association studies, we survey the main ways that the direct measurement of genetic variation across individuals is likely to contribute to economics, and we outline the challenges that have slowed progress in making these contributions. The most urgent problem facing researchers in this field is that most existing efforts to find associations between genetic variation and economic behavior are based on samples that are too small to ensure adequate statistical power. This has led to many false positives in the literature. We suggest a number of possible strategies to improve and remedy this problem: (a) pooling data sets, (b) using statistical techniques that exploit the greater information content of many genes jointly, and (c) focusing on economically relevant traits that are most proximate to known biological mechanisms.
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| 13. |
- Boso, Nathaniel, et al.
(författare)
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International entrepreneurial orientation and regional expansion
- 2017
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Ingår i: Entrepreneurship and Regional Development. - : Routledge. - 0898-5626 .- 1464-5114. ; 29:1-2, s. 4-26
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Tidskriftsartikel (refereegranskat)abstract
- This study examines how behavioral elements of international entrepreneurial orientation (i.e. product innovativeness, risk-taking, proactiveness, competitive aggressiveness, and autonomy) increase variability in scope of regional market expansion, and the international marketing channel management conditions under which this occurs. Results from an empirical study in a developing market show that not all behavioral elements of international entrepreneurial orientation (IEO) increase scope of regional expansion. The study specifically finds that scope of regional expansion is fostered when high levels of product innovation intensity, risk-taking, competitive aggressiveness, and autonomous behaviors are aligned with a stronger channel management capability. Conversely, the regional expansion values of product innovation novelty and proactiveness are cancelled out when channel management capability levels are high.
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| 14. |
- Broitman, Esteban, et al.
(författare)
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Nanoscale piezoelectric response of ZnO nanowires measured using a nanoindentation technique
- 2013
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 15:26, s. 11113-11118
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Tidskriftsartikel (refereegranskat)abstract
- We report the piezoelectric properties of ZnO nanowires (NWs) obtained by using a nanoindenter with a conductive boron-doped diamond tip. The direct piezoelectric effect was measured by performing nanoindentations under load control, and the generated piezoelectric voltage was characterized as a function of the applied loads in the range 0.2-6 mN. The converse piezoelectric effect was measured by applying a DC voltage to the sample while there was a low applied force to allow the tip being always in physical contact with the NWs. Vertically aligned ZnO NWs were grown on inexpensive, flexible, and disposable paper substrates using a template-free low temperature aqueous chemical growth method. When using the nanoindenter to measure the direct piezoelectric effect, piezopotential values of up to 26 mV were generated. Corresponding measurement of the converse piezoelectric effect gave an effective piezoelectric coefficient d(33)(eff) of similar to 9.2 pm V-1. The ZnO NWs were also characterized using scanning electron microscopy, X-ray diffraction, and high-resolution transmission electron microscopy. The new nanoindentation approach provides a straightforward method to characterize piezoelectric material deposited on flexible and disposable substrates for the next generation of nanodevices.
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| 15. |
- Bui, Thong, et al.
(författare)
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Factors Influencing the Success of E-Marketplaces
- 2005
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Ingår i: Proceedings of ISBE.
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Konferensbidrag (refereegranskat)abstract
- Purpose: The purpose of this paper has been to study factors that influence the success of e-marketplaces. Due to the development of internet and information technology, a new business model called electronic marketplace emerged in recent years. Electronic marketplace (e-marketplace) is a website where buyers and sellers can trade and close deals. The popularity of e-marketplaces reached its peak in the year of 2000, when the number of start-up marketplaces was nearly 1,500. However, only seven hundred of them existed in July 2002. This fact made us interested in the question of what factors contribute to the success of e-marketplaces. Design/Methodology/Approach: We used case study method. The selected samplings are PT, an e-marketplace in mobile phone and PO, in print matters. Our data was collected from the companies' documents, websites, and in-depth telephone interviews with the owners and managers.Findings: Two types of industries that may be advantageous for e-marketplace have no connection to the literature; industries that have problems of unethical or unserious players and industries where products become out of date and prices fall very quickly. Some classic business rules of thumb are still applicable in this online context. E.g., PT still emphasized the importance of developing close relationship with members. One e-marketplace involved in sales activities, and it is surprised to learn that this makes up the biggest part of revenue of the company.Implications: First, e-marketplace can promote security and trust to its trading community as a value proposition, especially for those markets with low degree of trust and security. Second, in order to build liquidity, e-marketplaces can focus on customer relationship and implement many measures to develop a tight bond between members. Third, e-marketplaces can also involve selling activities and generate considerable revenues.Originality/Value: There is some previous research about success factors for e-marketplaces, but most of it is applicable for very large e-marketplaces. To our knowledge, there is no research on the issue with small business to business e-marketplaces. Another unique feature of our study is that two investigated e-marketplaces that are selected for our sample are start-ups and based in Sweden, and though very small in terms of employees, but are still able to operate their business on a global scale. The findings have practical contribution to the SME community, especially those involved in e-commerce.
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| 16. |
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| 17. |
- Danielsson, L, et al.
(författare)
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Human monoclonal antibodies with different fine-specificity for digoxin derivatives: Cloning of heavy and light chain variable region sequences
- 1991
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Ingår i: Immunology. - 0019-2805. ; 74:1, s. 50-54
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Tidskriftsartikel (refereegranskat)abstract
- Human-mouse hybridoma cell lines producing human monoclonal antibodies against the cardiac glycoside digoxin were established after in vitro immunization or direct immortalization of human peripheral blood lymphocytes with digoxin. Three antibodies, designated M06, LH92 and LH 1 14, displayed different patterns of fine specificity against digoxin and several digoxin analogues, as elucidated by inhibition ELISA. All three monoclonal antibodies had p heavy chains, two of them (M06 and LH 114) had K light chains and one (LH92) A light chains. DNA encoding the variable regions of both heavy and light chains of the three antibodies were amplified from cDNA using the polymerase chain reaction (PCR). The nucleotide sequences of the amplified DNA were determined after subcloning of PCR fragments in M13 vectors. The deduced amino acid sequences revealed considerable sequence differences in the complementarity determining regions between the three antibodies.
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| 18. |
- Donbesuur, Francis, et al.
(författare)
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Growth implications of creation and discovery behavior among family firms : the moderating role of venture age
- 2023
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Ingår i: International Journal of Entrepreneurial Behaviour & Research. - : Emerald Group Publishing Limited. - 1355-2554 .- 1758-6534. ; 29:1
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Tidskriftsartikel (refereegranskat)abstract
- Purpose The aim of the study is to examine the effects of opportunity creation and discovery on the performance of family firms. Specifically, from the tenets of dynamic capabilities and organizational contingency perspectives, this study proposes and tests a framework of how family firms' creation and discovery behavior impact venture growth and the conditions under which such impact can vary. Design/methodology/approach The study uses moderated-hierarchical regression to analyze survey data from 156 family-owned small and medium-sized enterprises (SMEs) operating within a sub-Saharan African economy. Findings The findings indicate that creation behavior has a curvilinear U-shaped relationship with venture growth, while discovery behavior has a direct positive relationship with venture growth. Further analysis reveals that the curvilinearity of the U-shaped relationship between creation and venture growth will be stronger for older family firms than for younger ones. Research limitations/implications The study findings may be limited by the cross-sectional nature of the data and the specific focus on family firms only. Practical implications The results highlight the significance of pursuing both opportunities among family firms. In fact, both creation and discovery opportunities are significant drivers of family firm growth, albeit in different capacities. Relatedly, managers of older family firms (compared to younger firms) can invest more in exploiting creative opportunities. Social implications From these findings, governments and other stakeholders should create enabling environment and institutional frameworks conducive to exploiting opportunities by entrepreneurial firms. Originality/value The study is novel - as it provides unique findings on the performance implications of creation and discovery behavior of entrepreneurial family firms within developing economies.
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| 19. |
- Engberg, David
(författare)
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Atom Probe Tomography of TiSiN Thin Films
- 2015
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis concerns the wear resistant coating TiSiN and the development of the analysis technique atom probe tomography (APT) applied to this materials system. The technique delivers compositional information through time-of-flight mass spectrometry, with sub-nanometer precision in 3D for a small volume of the sample. It is thus a powerful technique for imaging the local distribution of elements in micro and nanostructures. To gain the full benefits of the technique for the materials system in question, I have developed a method that combines APT with isotopic substitution, here demonstrated by substitution of natN with 15N. This alters the time-of-flight of ions with of one or more N and will thereby enable the differentiation of the otherwise inseparable isotopes 14N and 28Si. Signs of small-scale fluctuations in the data led the development of an algorithm needed to properly visualize these fluctuations. A method to identify the best sampling parameter for visualization of small-scale compositional fluctuations was added to an algorithm originally designed to find the best sampling parameters for measuring and visualizing strong compositional variations. With the identified sampling parameters, the nano-scale compositional fluctuations of Si in the metal/metalloid sub-lattice could be visualized. The existence and size of these fluctuations were corroborated by radial distribution functions, a technique independent of the previously determined sampling parameter. The radial distribution function algorithm was also developed further to ease in the interpretation. The number of curves could thereby be reduced by showing elements, rather than single and molecular ions (of which there were several different kinds). The improvement of the algorithm also allowed interpretation of signs regarding the stoichiometry of SiNy. With a combination of analytical transmission electron microscopy and APT we show Si segregation on the nanometer scale in arc-deposited Ti0.92Si0.0815N and Ti0.81Si0.1915N thin films. APT composition maps and proximity histograms generated from Ti-rich domains show that the TiN 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.
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| 20. |
- Engberg, David L. J., 1986-
(författare)
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Atom Probe Tomography of Hard Nitride and Boride Thin Films
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hard ceramic thin films, including TiSiN, ZrAlN, ZrB2, and ZrTaB2, with applications for wear-resistant coatings, have been studied using atom probe tomography and correlated with several other analytical techniques, including X-ray diffraction, electron microscopy, and elastic recoil detection analysis. Outstanding obstacles for quantitative atom probe tomography of ceramic thin films have been surmounted.Mass spectral overlaps in TiSiN, which make 28Si indistinguishable from 14N, was resolved by isotopic substitution with 15N, and the nanostructural distribution of elements was thus revealed in 3-D, which enabled the identification of additional structural elements within the nanostructured Ti0.81Si0.1915N film. Improvements to the growth model of TiSiN by cathodic arc deposition was suggested.A self-organized nanolabyrinthine structure of ZrAlN, consisting of standing lamellae of fcc-ZrN and hexagonal AlN, was investigated with focus on the onset and limits of the self-organization. The local crystallographic orientational relationships were (001)ZrN || (0001)AlN and <110>ZrN || <2-1-10>AlN. Close to the MgO substrates, a smooth transition region was formed, going from segregated and disordered to the self-organized nanolabyrinthine structure. With increased growth temperature, coarse (111)-oriented ZrN grains occasionally precipitated and locally replaced the nanolabyrinthine structure. Significant local magnification effects rendered the Zr and N signals unusable, thereby inhibiting quantitative compositional analysis of the constituent phases, but the nanostructure was resolved using the Al signal.Ceramic materials are often affected by correlated evaporation, which can result in losses due to the detector dead-time/space. A compositional correction procedure was suggested, tested against an established procedure, and applied to ZrB2. The correction was found to be less dependent on the isotope abundances and background correction compared to the established procedure. While losses due to dead-time/space occur in atom probe tomography of all materials, the correlative field evaporation behavior of ceramics significantly increases the compositional error. The evaporation behavior of ZrB2 was therefore thoroughly investigated and evidence of preferential retention, correlated evaporation, and inhomogeneous field distributions at a low-index pole was presented. The high mass resolution, relatively low multiple events percentage, and quality of the co-evaporation correlation data was partly attributed to the crystal structure and film orientation, which promoted a layer-by-layer field evaporation.The evaporation behavior of the related ZrTaB2 films was found to be similar to that of ZrB2. The distribution of Ta in relation to Zr was investigated, showing that the column boundaries were both metal- and Ta-rich, and that there was a significant amount of Ta in solid solution within the columns.In addition, an instrumental artefact previously not described in atom probe tomography was found in several of the materials investigated in this thesis. The artefact consists of high-density lines along the analysis direction, which cannot be related to pole artefacts. The detection system of the atom probe was identified as the cause, because the artefact patterns on detector histograms coincided with the structure of the microchannel plate. Inconsistencies in the internal boundaries of the microchannel plate multifibers from the manufacturing process can influence the signal to the detector and locally increase the detection efficiency in a pattern characteristic to the microchannel plate in question.Altogether, this thesis shows that atom probe tomography of nitride and boride thin films is burdened by several artefacts and distortions, but that relevant material outcomes can nevertheless be achieved by informed choices of film isotopic constituents and analytical parameters, exclusion of heavily distorted regions (such as pole artefacts), and the use of compositional correction procedures when applicable.
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| 21. |
- Engberg, David L. J., et al.
(författare)
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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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Annan publikation (övrigt vetenskapligt/konstnärligt)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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| 22. |
- Eriksson, Anders, et al.
(författare)
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Arc deposition of Ti–Si–C–N thin films from binary and ternary cathodes — Comparing sources of C
- 2012
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Ingår i: Surface & Coatings Technology. - : Elsevier. - 0257-8972 .- 1879-3347. ; 213, s. 145-154
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Tidskriftsartikel (refereegranskat)abstract
- Ti–Si–C–N thin films with composition of 1–11 at.% Si and 1–20 at.% C have been deposited onto cemented carbide substrates by arcing Ti–Si cathodes in a CH4 + N2 gas mixture and, alternatively, through arcing Ti–Si–C cathodes in N2. Films of comparable compositions from the two types of cathodes have similar structure and properties. Hence, C can be supplied as either plasma ions generated from the cathode or atoms from the gas phase with small influence on the structural evolution. Over the compositional range obtained, the films were dense and cubic-phase nanocrystalline, as characterized by X-ray diffraction, ion beam analysis, and scanning and transmission electron microscopy. The films have high hardness (30–40 GPa by nanoindentation) due to hardening from low-angle grain boundaries on the nanometer scale and lattice defects such as growth-induced vacancies and alloying element interstitials.
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| 23. |
- Eriksson, Anders, et al.
(författare)
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Layer Formation by Resputtering in Ti-Si-C Hard Coatings during Large Scale Cathodic Arc Deposition
- 2011
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Ingår i: Surface & Coatings Technology. - : Elsevier. - 0257-8972 .- 1879-3347. ; 205:15, s. 3923-3930
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the physical mechanism behind the phenomenon of self-layering in thin films made by industrial scale cathodic arc deposition systems using compound cathodes and rotating substrate fixture. For Ti-Si-C films, electron microscopy and energy dispersive x-ray spectrometry reveals a trapezoid modulation in Si content in the substrate normal direction, with a period of 4 to 23 nm dependent on cathode configuration. This is caused by preferential resputtering of Si by the energetic deposition flux incident at high incidence angles when the substrates are facing away from the cathodes. The Ti-rich sub-layers exhibit TiC grains with size up to 5 nm, while layers with high Si-content are less crystalline. The nanoindentation hardness of the films increases with decreasing layer thickness.
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| 24. |
- Eriksson, Anders, et al.
(författare)
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Ti-Si-C-N Thin Films Grown by Reactive Arc Evaporation from Ti3SiC2 Cathodes
- 2011
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Ingår i: Journal of Materials Research. - : Cambrdige University Press. - 0884-2914 .- 2044-5326. ; 26, s. 874-881
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Tidskriftsartikel (refereegranskat)abstract
- Ti-Si-C-N thin films were deposited onto WC-Co substrates by industrial scale arc evaporation from Ti3SiC2 compound cathodes in N2 gas. Microstructure and hardness were found to be highly dependent on the wide range of film compositions attained, comprising up to 12 at.% Si and 16 at.% C. Nonreactive deposition yielded films consisting of understoichiometric TiCx, Ti and silicide phases with high (27 GPa) hardness. At a nitrogen pressure of 0.25-0.5 Pa, below that required for N saturation, superhard, 45-50 GPa, (Ti,Si)(C,N) films with a nanocrystalline feathered structure were formed. Films grown above 2 Pa displayed crystalline phases of more pronounced nitride character, but with C and Si segregated to grain boundaries to form weak grain boundary phases. In abundance of N, the combined presence of Si and C disturb cubic phase growth severely and compromises the mechanical strength of the films.
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| 25. |
- Fager, Hanna
(författare)
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Growth and Characterization of Amorphous TiAlSiN and HfAlSiN Thin Films
- 2012
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This Thesis explores amorphous transition metal nitrides for cutting tool applications. The aim is to extend the knowledge on amorphous nitride thin lms, to describe the growth process, and to explore ways of characterizing these novel complex materials.Thin lms of Ti-Al-Si-N and Hf-Al-Si-N were fabricated using industrial cathodic arc evaporation and magnetically-unbalanced reactive magnetron sputtering, respectively. The microstructure of the lms was studied using x-ray diraction (XRD) and transmission electron microscopy (TEM), while compositional analysis of the lms was performed by spectroscopic techniques (EDS, SIMS, and RBS). The mechanical properties were investigated by nanoindentation.The Ti-Al-Si-N lms were grown on cemented carbide substrates using Ti-Al-Si compound cathodes in an N2 atmosphere. High Al and Si concentrations in the lms (i.e., 12 at% Si and 18 at% Al) promote renucleation and result in x-ray amorphous lms. High resolution TEM (HRTEM) reveals isolated grains, ~2 nm in size, embedded in an amorphous matrix. Annealing experiments show that the lms are thermally stable up to 900 oC. They exhibit age hardening, with an increase in hardness from 21.9 GPa for as-deposited lms to 31.6 GPa at 1000 oC. At 1100 oC severe out-diusion of Co and W from the substrate occurs, and the lms recrystallize into c-TiN and w-AlN.The single layer Hf-Al-Si-N and multilayer Hf-Al-Si-N/HfN lms were grown on Si(001) substrates from a single Hf0:60Al0:20Si0:20 alloy target in an N2/Ar atmosphere. The composition and nanostructure of the lms was controlled during growth by independently varying the ion energy (Ei) and the ion-to-metal flux ratio (Ji=JMe). With Ji/JMe=8, the nanostructure and composition of the lms changes from x-ray amorphous with a Hf content of 0.6, to an amorphous matrix with encapsulated nanocrystals with 0.66≤Hf≤0.84, to nanocrystalline with 0.96≤Hf≤1.00, when increasing Ei from 15 to 65 eV. Varying Ji=JMe with Ei=13 eV yields electron-diraction amorphous lms at substrate temperatures of 100 oC. Hf-Al-Si-N/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 from 20 GPa with Λ=20 nm to 27 GPa with Λ=2 nm.̴
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