James P. Best

James P. Best
Max Planck Institute for Iron Research GmbH | MPIE · Department of Structure and Nano-/ Micromechanics of Materials

PhD

About

69
Publications
18,798
Reads
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3,098
Citations
Citations since 2016
47 Research Items
2660 Citations
20162017201820192020202120220100200300400500
20162017201820192020202120220100200300400500
20162017201820192020202120220100200300400500
20162017201820192020202120220100200300400500
Introduction
With the continual downsizing of technologies, the link between advanced materials characterisation and industrial activity is becoming increasingly relevant. Dr. Best's group at the Max-Planck-Institute for Iron Research focuses on understanding small-scale mechanics of thin-film (and other advanced material technologies), and how the mechanical response of materials correlate to their chemical distribution at an atomic-scale.
Additional affiliations
August 2019 - March 2020
RWTH Aachen University
Position
  • Senior Researcher
December 2017 - March 2020
UNSW Sydney
Position
  • Research Associate
August 2013 - July 2017
Empa - Swiss Federal Laboratories for Materials Science and Technology
Position
  • PostDoc Position

Publications

Publications (69)
Article
Full-text available
For the implementation of thin ceramic hard coatings into intensive application environments, the fracture toughness is a particularly important material design parameter. Characterisation of the fracture toughness of small-scale specimens has been a topic of great debate, due to size effects, plasticity, residual stress effects and the influence o...
Article
Full-text available
Micro-pillar splitting at temperatures up to 500 °C was used to evaluate the toughness for a series of thin physical vapour deposited ceramic-nitride coatings. When compared to ion beam notched geometries, this testing ap- proach reduces the likelihood of ion impregnation within a material volume where fracture may initiate. A tough- ness increase...
Article
Full-text available
High strain rate micromechanical testing can assist researchers in elucidating complex deformation mechanisms in advanced material systems. In this work, the interactions of atomic-scale chemistry and strain rate in affecting the deformation response of a Zr-based metallic glass was studied by varying the concentration of oxygen dissolved into the...
Article
Full-text available
Bulk‐scale (2¯$\bar{2}$01)‐oriented monoclinic beta‐phase gallium oxide (β‐Ga2O3) single crystals are brittle and fracture at low compressive strains. Here, it is reported that submicron β‐Ga2O3 pillars exhibit an exceptional room temperature plastic strain of up to ≈22% under compression. Deformation is observed in transition from brittle to super...
Article
Laser powder bed fusion is an established and viable method to produce large and complex bulk metallic glass geometries. However, the thermal gradients and cooling rates during processing are affected by geometric features, in particular close to the part-powder bed interface, which may impair vitrification and mechanical properties. As such, the p...
Article
Recent experimental and computational studies at different scales reveal an apparent flow-induced anisotropy of the inelastic deformation behaviour in metallic glasses (MGs). However, the anisotropic damage behaviour accompanied by the formation of shear bands is not adequately described in the previous constitutive modelling work. In this study, w...
Article
The Mg-Al-Ca system has been shown to be a promising alloy system since it combines the low density of Mg with a high creep resistance at high alloying contents and a high ductility for dilute alloys, while simultaneously avoiding the requirement of alloying with costly rare earth elements. Nevertheless, the adequate preparation of the alloy system...
Article
Full-text available
Additive manufacturing of bulk metallic glasses (BMGs) has opened this material class to an exciting new range of potential applications, as bulk-scale, net-shaped amorphous components can be fabricated in a single step. However, there exists a critical need to understand the structural details of additive manufactured BMGs and how the glassy struc...
Article
Experimental differentiation of individual strengthening effects from the nanoscale precipitates in Alloy 718 remains challenging due to co-precipitation of γ′ and γ′′. Here, we examine a region adjacent to the δ-phase consisting of γ-matrix containing γ′-precipitates only. The width and compositional profile of this γ′′-free zone is uncovered via...
Article
Full-text available
Thin film metallic glasses (TFMGs) are a novel class of materials showing a mutual combination of large plastic deformation in tension (>10% strain) and superior yield strength up to ∼3.5 GPa, which make them ideal candidates for applications such as flexible electronics. Nevertheless, a clear relationship between the atomic structure and mechanica...
Article
Full-text available
Interstitials, e.g., C, N, and O, are attractive alloying elements as small atoms on interstitial sites create strong lattice distortions and hence substantially strengthen metals. However, brittle ceramics such as oxides and carbides usually form, instead of solid solutions, when the interstitial content exceeds a critical yet low value (e.g., 2 a...
Article
The impact of a coherent twin boundary (CTB) on the size scaling of the shear stress in micropillar compression tests has been investigated through microcompression of bi-crystalline pillars containing a vertical CTB, as well as single-crystalline pillars in three different nominal diameters of 1, 3 and 5 µm. While both, single- and bi-crystalline...
Article
Full-text available
Dislocation-enhanced electrical conductivity is an emerging topic for ceramic oxides. In contrast to the majority of present studies which focus on large-scale crystal deformation or thin film fabrication to introduce dislocations, we use a nanoindentation “pop-in stop” method to locally generate 〈011〉 edge-type dislocations at room temperature, wi...
Article
Science-driven design of future thermoelectric materials requires a deep understanding of the fundamental relationships between microstructure and transport properties. Grain boundaries in polycrystalline materials influence the thermoelectric performance through the scattering of phonons or the trapping of electrons due to space-charge effects. Ye...
Preprint
Full-text available
Science-driven design of future thermoelectric materials requires a deep understanding of the fundamental relationships between microstructure and transport properties. Grain boundaries in polycrystalline materials influence the thermoelectric performance through the scattering of phonons or the trapping of electrons due to space-charge effects. Ye...
Article
Full-text available
In this paper, a novel approach is presented to tailor the stress properties of diamond thin films via boron doping and micro-fabrication of bridges using focused ion beam milling. The experimental data, based on detailed confocal micro-Raman investigations, are supported and interpreted through finite element method calculations of the stress dist...
Article
The combination of refined microstructures (induced by rapid cooling) and melt pool-induced mesostructures in AlSi10Mg fabricated using laser powder bed fusion (LPBF) – a widely used additive manufacturing technique – impart high strength and fracture toughness. Further exploitation of such property combinations requires a detailed understanding of...
Article
Full-text available
Selective laser melting (SLM) is a promising powder bed based additive manufacturing technique for the near-net-shape production of large-scale bulk metallic glasses (i.e. 3D-printed BMGs). Initial defects such as pores inherent to the SLM process are regarded as key factors for the mechanical integrity of BMGs. Here the structural defects in the f...
Article
Laser additive manufacturing of bulk metallic glass (BMG) provides an effective bypassing of the critical casting thickness constraints that limit the size of components that can be produced; however, open questions remain regarding the resulting mechanical properties. In this work, a Zr-based glass with composition Zr59.3Cu28.8Nb1.5Al10.4 was prin...
Article
This work considers the resulting material structural effects of laser-processing chemical vapor deposited (CVD) diamond. The utilized 532 nm wavelength laser had a pulse duration of 40 ns together with a spot diameter of ca. 40 μm. The effect of cutting fluence on the CVD diamond microstructure was investigated using both Raman and transmission el...
Article
Full-text available
Recently, fabrication of bulk metallic glasses (BMGs) components with complex shapes has been realized using laser powder bed fusion (PBF). Initial defects such as porosity inherent to the PBF process can significantly degrade the mechanical integrity of the BMGs components. In spite of intensive studies on pore structures in 3D-printed crystalline...
Article
Full-text available
A Zr-based bulk metallic glass produced using selective laser melting (SLM) was compared to the same alloy fabricated using traditional suction-casting. Analysis of the fracture toughness and mechanism through single edge notched beam bending experiments show a significantly reduced damage tolerance for the laser-processed material (KQ ~ 138.0 ± 13...
Article
Microfabrication of synthetic single crystal diamond using accelerated helium ions beams has significant potential for functional applications such as high precision optical devices, through tailoring of the optical properties via diamond graphitization. The use of helium ion microscopes (HIM) with nano-scaled focused ion beam spot sizes also allow...
Article
Full-text available
Additive manufacturing of bulk metallic glasses (BMGs) allows for effective bypassing of critical casting thickness constraints for glassy alloys, opening this exciting materials class up to new applications. An open question is how the laser processing of such materials affects the short-range structural order; a critical mediating parameter for g...
Article
Titanium diboride (TiB 2 ) is a hard coating with a hexagonal crystal structure that maintains its high hardness and inertness at elevated temperatures, even in contact with aluminum and its alloys. Therefore, titanium diboride coatings are often used in cutting, forming, injection molding and tribological applications. While there are multiple dep...
Article
Effective strategies to improve the tarnishing resistance of the 18 K (karat) gold-based bulk glass-forming composition Au49Ag5.5Pd2.3Cu26.9Si16.3 were recently found, with the addition of Ga at the expense of Cu and a sufficient reduction of Si. However, the modification of the alloy is accompanied by a reduction of the glass-forming ability (GFA)...
Article
Optimally, hard protective coatings should effectively absorb impact energy to reduce the likelihood of failure events. In this work, an arc-PVD approach was utilised for the deposition of thick ceramic multilayer AlCrTiN/CrN-based coatings containing a distribution of metallic nickel inclusions throughout sequential CrN-based interlayers. The aim...
Article
The effect of extracellular polymeric substances (EPS) on the meso-scale physical structure and hydraulic resistance of membrane biofilms during gravity driven membrane (GDM) filtration was investigated. Biofilms were developed on the surface of ultrafiltration membranes during dead-end filtration at ultra-low pressure (70 mbar). Biofilm EPS compos...
Article
Experiments and theory are employed to investigate the thermal damage induced by infra-red nanosecond pulses in atmospheric air into a boron-doped diamond target. Micro-Raman spectroscopy, Transmission Electron Microscopy (TEM) analysis and surface topography measurement are used to investigate the carbon phase created during the rapid heating and...
Article
High-impact applications such as forging, punching or fine blanking often utilise hard-coating systems to improve wear and lifetime performance. For rational design of such systems, evaluation after repeated impacts at the application temperature is critical. However, such investigations are time-consuming and costly to perform in-line on an indust...
Conference Paper
Full-text available
Skeletal diseases such as osteoporosis constitute a seri-ous socio-economic burden in aging societies. Patient specific tissue strength estimation could be helpful for personalised treatment strategies. Reference point in-dentation (RPI) [1] that derives from instrumented in-dentation [2] has been proposed. With imprints of sev-eral 100 μm at inden...
Article
Full-text available
Direct writing utilizing a focused electron beam constitutes an interesting alternative to resist based techniques, as it allows for precise and flexible growth onto any conductive substrate in a single-step process. One important challenge, however, is the identification of appropriate precursors which allow for deposition of the material of choic...
Article
Melt spinning and drawing of amorphous cyclo-olefin and co-polyamide polymeric materials were performed to develop mono-component continuous filaments. Raman spectroscopy was employed to assess the effect of a static bending deformation on the microstructure of the filaments. Spectra stemming from the fiber regions under tensile and compressive loa...
Article
Full-text available
An effective post growth electrical tuning, via an oxygen releasing-method, to enhance the content of non-noble metals in deposits directly written with gas-assisted focused-electron-beam-induced deposition (FEBID) is presented. It represents a novel and reproducible method for improving the electrical transport properties of Co-C deposits. The met...
Article
The micro-mechanical fracture behavior of single crystalline silicon was investigated as a function of temperature in situ in the scanning electron microscope equipped with a nanoindenter. A gradual but continuous increase in KC was observed with increasing temperature above 300 °C, in contrast to the sharp transitions observed in earlier works. No...
Article
In a recent commentary to our manuscript "Mechanical properties of cortical bone and their relationships with age, gender, composition and microindentation properties in the elderly" Thurner [1] discusses several points that should be regarded in investigations of extra-cellular matrix properties with respect to age and gender. Thurner specifically...
Article
Highly ordered anodic aluminum oxide (AAO) films were fabricated using a two-step anodization process in oxalic acid, sulfuric acid, or ethylene glycol containing sulfuric acid, which are important in design of nanostructured optical devices. The morphology and UV-Vis reflectance spectroscopy of these films were analyzed. The morphological paramete...
Article
Hard coatings are used extensively to protect tools in forming, forging and milling operations. While modern deposition of hard coatings using plasma methodologies has opened industry up to a new range of potential coating systems, challenges remain regarding coating optimization under specific conditions and environments. In the presented work a p...
Article
The growing incidence of skeletal fractures poses a significant challenge to ageing societies. Since a major part of physiological loading in the lower limbs is carried by cortical bone, it would be desirable to better understand the structure-mechanical property relationships and scale effects in this tissue. This study aimed at assessing whether...
Article
Full-text available
Thin-film multilayer stacks of mechanically hard magnetron sputtered indium tin oxide (ITO) and mechanically soft highly porous surface anchored metal-organic framework (SURMOF) HKUST-1 were studied using nanoindentation. Crystalline, continuous, and monolithic surface anchored MOF thin films were fabricated using a liquid-phase epitaxial growth me...
Article
While small-scale fracture toughness measurements provide an extremely useful material parameter, notch preparation and ion-beam damage continue to be contentious issues. Herein we utilize a conventional gallium source for notching ceramic cantilevers, and compare against notches fabricated using xenon and helium ions from commercial focused ion mi...
Article
PEG (polyethylene glycol) hydrogel particles with tunable elasticity and with a similar size to human RBCs via a MS templating method, followed by investigation of particle deformability using atomic force microscopy (AFM) and a microfluidic blood capillary model was engineered. The elastic modulus of the PEG particles is quantified using liquid co...
Article
On page 7295, F. Caruso and co-workers report a mesoporous silica templating method for preparing super-soft PEG particles. The elasticity of the particles can be tuned to mimic the deformability behaviour of human red blood cells in a microfluidic blood-capillary model. These particles provide a new platform for investigating bio-nano interactions...
Article
Hybrid and multicompartment carriers are of significant interest for the development of next-generation therapeutic drug carriers. Herein, fundamental investigations on layer-by-layer (LbL) capsules consisting of two different polymers are presented. The hybrid systems were designed to have pH-responsive, charge-shifting poly(2-(diisopropylamino)et...
Article
We report the assembly of metal-polyphenol complex (MPC) films and capsules through the sequential deposition of iron(III) ions (Fe-(III)) and a natural polyphenol, tannic acid (TA), driven by metal-ligand coordination. Stable Fe-(III)/TA films and capsules were formed, indicating lateral and longitudinal cross-linking of TA by Fe-(III) in the film...
Thesis
Hydrogel materials have demonstrated unique potential for biomedical application in areas ranging from macroscopic tissue engineering scaffolds to targeted nanoparticles for in vivo therapeutic delivery. Such propensity for biological application is largely due to the inherently high degree of hydration and low rigidity of hydrogel networks, which,...
Article
The mechanical properties of the shell of lysozyme microbubbles, LSMBs, were evaluated by acoustic interrogation and nanoindentation techniques. The Young's modulus of LSMBs was found to be 1.0 ± 0.3 MPa and 0.6 ± 0.1 MPa when analyzed by flow cytometry and AFM, respectively. The shell elasticity and Young's modulus were not affected by the size of...
Article
Faceted polymer microcapsules are prepared from metal-organic framework (MOF) templates. The MOF templates are removable under mild aqueous conditions. The obtained microcapsules are stiffer than their spherical counterparts, reflecting the near-incompressibility of the facet edges, and indicating that the faceting might be a useful strategy for co...
Article
Soft hydrogel particles with tunable mechanical properties are promising for next-generation therapeutic applications. This is due to the increasingly proven role that physicochemical properties play in particulate-based delivery vectors, both in vitro and in vivo. The ability to understand and quantify the mechanical properties of such systems is...
Article
While soft hydrogel nano- and microstructures hold great potential for therapeutic treatments and in vivo applications, their nanomechanical characterization remains a challenge. In this paper, soft, single-component, supported hydrogel films were fabricated using pendant-thiol-modified poly(methacrylic acid) (PMASH). The influence of hydrogel arch...
Article
Full-text available
The development of facile and versatile strategies for thin-film and particle engineering is of immense scientific interest. However, few methods can conformally coat substrates of different composition, size, shape, and structure. We report the one-step coating of various interfaces using coordination complexes of natural polyphenols and Fe(III) i...
Article
DNA-loaded polypeptide particles are prepared via templated assembly of mesoporous silica for the delivery of adjuvants. The elasticity and cargo-loading capacity of the obtained particles can be tuned by the amount of cross-linker used to stabilize the polypeptide particles. The use of polypeptide particles as biocarriers provides a promising meth...
Article
Full-text available
We report engineered hydrogel thin-films with varying degrees of covalent crosslinking, which demonstrate enhanced HeLa cell adhesion with decreasing film stiffness. This trend is contrary to previous findings for tumour cell adhesion on hydrogel substrates, and is attributed to the extremely soft nature of the films studied, allowing for a greater...
Article
Nanoengineered particles that can facilitate drug formulation and passively target tumors have reached the clinic in recent years. These early successes have driven a new wave of significant innovation in the generation of advanced particles. Recent developments in enabling technologies and chemistries have led to control over key particle properti...
Article
Nanostructured particulate materials are expected to revolutionize diagnostics and the delivery of therapeutics for healthcare. To date, chemistry-derived solutions have been the major focus in the design of materials to control interactions with biological systems. Only recently has control over a new set of physical parameters, including size, sh...