| 1. |
- Bakhit, Babak, et al.
(författare)
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Strategy for simultaneously increasing both hardness and toughness in ZrB2-rich Zr1-xTaxBy thin films
- 2019
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Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : A V S AMER INST PHYSICS. - 0734-2101 .- 1520-8559. ; 37:3
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Tidskriftsartikel (refereegranskat)abstract
- Refractory transition-metal diborides exhibit inherent hardness. However, this is not always sufficient to prevent failure in applications involving high mechanical and thermal stress, since hardness is typically accompanied by brittleness leading to crack formation and propagation. Toughness, the combination of hardness and ductility, is required to avoid brittle fracture. Here, the authors demonstrate a strategy for simultaneously enhancing both hardness and ductility of ZrB2-rich thin films grown in pure Ar on Al2O3(0001) and Si(001) substrates at 475 degrees C. ZrB2.4 layers are deposited by dc magnetron sputtering (DCMS) from a ZrB2 target, while Zr1-xTaxBy alloy films are grown, thus varying the B/metal ratio as a function of x, by adding pulsed high-power impulse magnetron sputtering (HiPIMS) from a Ta target to deposit Zr1-xTaxBy alloy films using hybrid Ta-HiPIMS/ZrB2-DCMS sputtering with a substrate bias synchronized to the metal-rich portion of each HiPIMS pulse. The average power P-Ta (and pulse frequency) applied to the HiPIMS Ta target is varied from 0 to 1800W (0 to 300 Hz) in increments of 600W (100 Hz). The resulting boron-to-metal ratio, y = B/(Zr+Ta), in as-deposited Zr1-xTaxBy films decreases from 2.4 to 1.5 as P-Ta is increased from 0 to 1800W, while x increases from 0 to 0.3. A combination of x-ray diffraction (XRD), glancing-angle XRD, transmission electron microscopy (TEM), analytical Z-contrast scanning TEM, electron energy-loss spectroscopy, energy-dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy, and atom-probe tomography reveals that all films have the hexagonal AlB2 crystal structure with a columnar nanostructure, in which the column boundaries of layers with 0 amp;lt;= x amp;lt; 0.2 are B-rich, whereas those with x amp;gt;= 0.2 are Ta-rich. The nanostructural transition, combined with changes in average column widths, results in an similar to 20% increase in hardness, from 35 to 42 GPa, with a simultaneous increase of similar to 30% in nanoindentation toughness, from 4.0 to 5.2MPa root m. Published by the AVS.
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| 2. |
- Bolter, Jay David, et al.
(författare)
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Media studies, mobile augmented reality, and interaction design
- 2013
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Ingår i: interactions. - : ACM. - 1072-5520 .- 1558-3449. ; 20:1, s. 36-45
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- You are walking in the Sweetwater Creek State Park near Atlanta and using the Augmented Reality (AR) Trail Guide, a mobile application designed by Isaac Kulka for the Argon Browser (Figure 1). The application offers two views: a now familiar Google-style map, with points of interest marked on its surface, and an AR view, which shows these points located in space. You see the map view when you hold the screen parallel to the ground; when you turn the phone up to look at the world, you get the AR view with the points of interest floating in space in front of you. This simple gesture of raising the phone changes your relationship to the information. You pass from a fully symbolic form of representation to a form of perceiving symbolic information as part of your visual environment. The AR Trail Guide, developed in the Augmented Environments Lab at Georgia Tech [1], illustrates a new realm in AR design that goes beyond current commercial applications. In this article, we discuss some of these new areas, such as designing for experiences in cultural heritage, personal expression, and entertainment. At the same time, we want to address a larger issue. ACM interactions has often been a place for exploring new paradigms and the relevance for interaction design of unusual approaches from other disciplines. In that spirit, we pose the question: Can the humanistic discipline of media studies play a useful role in interaction design? Media studies looks at the history of media and their relationship to culture, and we will focus here on digital media and their relationship to other media, both present and past. Looking at digital media in a historical context is relevant because of the dynamic relationship between "traditional" media (film, television, radio, print) and their digital remediations. How can media studies be made to contribute to the productive work of interaction design? We believe one answer lies in using the historical understanding gained through media studies to develop a kind of media aesthetics that can guide designers as they explore new forms of digital media such as the mobile augmented reality application described above.
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| 3. |
- Bolter, Jay David, 1951-, et al.
(författare)
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Reality Media : Augmented and Virtual Reality
- 2021. - 1
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Bok (refereegranskat)abstract
- How augmented reality and virtual reality are taking their places in contemporary media culture alongside film and television.This book positions augmented reality (AR) and virtual reality (VR) firmly in contemporary media culture. The authors view AR and VR not as the latest hyped technologies but as media—the latest in a series of what they term “reality media,” taking their place alongside film and television. Reality media inserts a layer of media between us and our perception of the world; AR and VR do not replace reality but refashion a reality for us. Each reality medium mediates and remediates; each offers a new representation that we implicitly compare to our experience of the world in itself but also through other media.The authors show that as forms of reality media emerge, they not only chart a future path for media culture, but also redefine media past. With AR and VR in mind, then, we can recognize their precursors in eighteenth-century panoramas and the Broadway lights of the 1930s. A digital version of Reality Media, available through the book's website, invites readers to visit a series of virtual rooms featuring interactivity, 3-D models, videos, images, and texts that explore the themes of the book.
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| 4. |
- Czarniawska, Barbara, 1948, et al.
(författare)
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Organisering kring hot och risk
- 2007
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- Hur hanteras blödarfeberviruset Marburg, hur förbereder man sig för ett eventuellt utbrott av fågelinfluensan, hur kalkylerar man hälsorisker i Europa och Sverige och hur hanterar man risk i samband med äventyrsturism? Vad har stormen Gudrun lärt oss om att hantera akuta situationer och hur skapar katastrofer som Tjörnbron handlingsföreträde i form av särskilda förutsättningar för organisering? Detta är några exempel på studier inkluderade i Organisering kring hot och risk. Boken tittar även närmare på hur man hanterar effekter av datorkriser, hur konst och vad betraktaren bedömer som hot kan bidra till skapande av handlingsnät samt hur tv-serien Kommissionen belyser det svenska beredningsarbetet. Författarna visar att karaktären av organisering kring hot och risk är beroende av tidpunkten: innan, under eller efter en katastrof eller en hotfull händelse. Beredningsarbetet består av resursmobilisering, att skissa planer, att bygga upp strukturer samt bygga eller mobilisera nätverk. När katastrofen väl inträffar visar det sig dock att även de bästa planer inte alltid fungerar som man vill och responsen på de faktiska händelserna består av improvisation samt av att bygga handlingskedjor och handlingsnät. Det finns inget recept på hur man skall organisera kring hot och risk men boken har identifierat ett återkommande problem: varje misslyckande verkar leda till slutsatsen att det behövs mer av planer och strukturer. Författarna hävdar motsatsen. Bokens budskap är att istället för att skapa oändliga planer och strukturer skall man öva lämpliga skickligheter och improvisationsförmåga. Boken vänder sig till studerande inom organisationsteori respektive riskhantering på universitet och högskola samt yrkesverksamma inom krisberedskap och riskhantering.
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| 5. |
- 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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| 6. |
- Engberg, David L. J., 1986-, et al.
(författare)
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Atom probe tomography field evaporation characteristics and compositional corrections of ZrB2
- 2019
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Ingår i: Materials Characterization. - : Elsevier BV. - 1044-5803 .- 1873-4189. ; 156
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Tidskriftsartikel (refereegranskat)abstract
- The microstructure of stoichiometric ZrB2.0 and B over-stoichiometric ZrB2.5 thin films has been studied using atom probe tomography (APT), X-ray diffraction, and transmission electron microscopy. Both films consist of columnar ZrB2 grains with AlB2-type crystal structure. The narrow stoichiometry range of ZrB2 results in the presence of separate disordered B-rich boundaries even in ZrB2.0. At higher average B content, specifically ZrB2.5, the formation of a continuous network around the sides of the ZrB2 columns is promoted. In addition, the APT field evaporation characteristics of ZrB2 and its influence on the measured local composition has been studied and compared to the average composition from elastic recoil detection analysis (ERDA). Differences in the measured average compositions of the two techniques are explained by the APT detector dead-time/space. A new pile-up pairs correction procedure based on co-evaporation correlation data was thus employed here for the APT data and compared with the 10B-method (the B equivalence of the 13C-method), as well as the combination of both methods. In ZrB2.0, all of the applied compositional correction methods were found to reduce the compositional difference when appropriate isotopic abundances were used. In ZrB2.5, the inhomogeneity of the film likely increased the local APT composition to such an extent that even conservative correction procedures overestimated the B content compared to the ERDA reference. The strengths of the pile-up pairs correction compared the 10B and the combined methods are higher precision, due to it being less dependent on the accuracy of estimated isotopic abundances, and that the correction itself is not dependent on careful background correction of the mass spectrum.
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| 7. |
- 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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| 8. |
- Engberg, David L. J., et al.
(författare)
-
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
-
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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| 9. |
- Engberg, David, et al.
(författare)
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Resolving mass spectral overlaps in atom probe tomography by isotopic substitutions – case of TiSi15N
- 2018
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Ingår i: Ultramicroscopy. - : Elsevier BV. - 1879-2723 .- 0304-3991. ; 184, s. 51-60
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Tidskriftsartikel (refereegranskat)abstract
- Mass spectral overlaps in atom probe tomography (APT) analyses of complex compounds typically limit the identification of elements and microstructural analysis of a material. This study concerns the TiSiN system, chosen because of severe mass-to-charge-state ratio overlaps of the 14 N + and 28 Si 2+ peaks as well as the 14N 2 + and 28 Si + peaks. By substituting 14 N with 15 N, mass spectrum peaks generated by ions composed of one or more N atoms will be shifted toward higher mass-to-charge-state ratios, thereby enabling the separation of N from the predominant Si isotope. We thus resolve thermodynamically driven Si segregation on the nanometer scale in cubic phase Ti 1- x Si x 15 N thin films for Si contents 0.08 ≤ x ≤ 0.19 by APT, as corroborated by transmission electron microscopy. The APT analysis yields a composition determination that is in good agreement with energy dispersive X-ray spectroscopy and elastic recoil detection analyses. Additionally, a method for determining good voxel sizes for visualizing small-scale fluctuations is presented and demonstrated for the TiSiN system.
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| 10. |
- Engberg, Maria, et al.
(författare)
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Cultural expression in augmented and mixed reality
- 2014
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Ingår i: Convergence. The International Journal of Research into New Media Technologies. - : Sage Publications. - 1354-8565 .- 1748-7382. ; 20:1, s. 3-9
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Most readers of Convergence will have some familiarity with the developing digital media forms that go under the name of augmented reality and mixed reality (MAR or separately, AR and MR). The widespread availability of smart phones in the last 10 years has redefined AR and MR that had previously been confined to the laboratory. Smart phones and tablets have become the platform for a variety of applications in which digital text, images, video, and audio are overlaid on the screen and appear to be present in the space around the user. In addition, the smart phone or tablet can typically determine the user’s location in the world and orientation in his/her immediate environment. Along with the commercial uses for location-sensitive advertising, new forms of cultural expression (e.g. for art, design, and social media) are beginning to appear. Appropriately for this journal, these new forms can best be studied by a convergence of disciplines, including media studies, art history, literary theory, philosophy (particularly phenomenology), interaction design, sociology, anthropology, communication studies, human–computer interaction, and computer science. Many of these disciplines are represented in the contributions in this special issue that focuses on the ways in which AR and MR participate in cultural expression in today’s heterogeneous media economy. Do AR and MR constitute a new medium? What are the specific qualities of the new medium that give rise to new forms of cultural expression? Are AR and MR two different media with different characteristic qualities and affordances? Over the past two decades, computer scientists have analyzed AR and MR as media forms from their own technical and operational perspectives (e.g. Milgram and Kashino, 1994). These questions are addressed from artistic and theoretical perspectives by the contributions to this special issue.
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