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1. Stability theory for metal pad roll in cylindrical liquid metal batteries

   https://doi.org/10.1017/jfm.2023.238  

   Herreman, W.; Wierzchalek, L.; Horstmann, G.M.; Cappanera, L.; Nore, C. (May 2023, Journal of Fluid Mechanics)

   When liquid metal batteries are charged or discharged, strong electrical currents are passing through the three liquid layers that we find in their interior. This may result in the metal pad roll instability that drives gravity waves on the interfaces between the layers. In this paper, we investigate theoretically metal pad roll instability in idealised cylindrical liquid metal batteries that were simulated previously by Weber et al. ( Phys. Fluids , vol. 29, no. 5, 2017 b , 054101) and Horstmann et al. ( J. Fluid Mech. , vol. 845, 2018, pp. 1–35). Near the instability threshold, we expect weakly destabilised gravity waves, and in this parameter regime, we can use perturbation methods to find explicit formulas for the growth rate of all possible waves. This perturbative approach also allows us to include dissipative effects, hence we can locate the instability threshold with good precision. We show that our theoretical growth rates are in quantitative agreement with previous and new direct numerical simulations. We explain how our theory can be used to estimate a lower bound on cell size beneath which metal pad roll instability is unlikely. 

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2. Tunable metal contacts at layered black-arsenic/metal interface forming during metal deposition for device fabrication

   https://doi.org/10.1038/s43246-022-00233-7  

   Kundu, Subhajit; Golani, Prafful; Yun, Hwanhui; Guo, Silu; Youssef, Khaled M.; Koester, Steven J.; Mkhoyan, K. Andre (December 2022, Communications Materials)

   Abstract Understanding the kinetics of interfacial reaction in the deposition of metal contacts on 2D materials is important for determining the level of contact tenability and the nature of the contact itself. Here, we find that some metals, when deposited onto layered black-arsenic films using e-beam evaporation, form a-few-nm thick distinct intermetallic layer and significantly change the nature of the metal contact. In the case of nickel, the intermetallic layer is Ni 11 As 8 , whereas in the cases of chromium and titanium they are CrAs and a-Ti 3 As, respectively, with their unique structural and electronic properties. We also find that temperature, which affects interatomic diffusion and interfacial reaction kinetics, can be used to control the thickness and crystallinity of the interfacial layer. In the field effect transistors with black-arsenic channel, due to the specifics of its formation, this interfacial layer introduces a second and more efficient edge-type charge transfer pathway from the metal into the black-arsenic. Such tunable interfacial metal contacts could provide new pathways for engineering highly efficient devices and device architectures. 

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3. Liquid metal nanocomposites

   https://doi.org/10.1039/d0na00148a  

   Malakooti, Mohammad H.; Bockstaller, Michael R.; Matyjaszewski, Krzysztof; Majidi, Carmel (July 2020, Nanoscale Advances)

   Liquid metal (LM) has attracted tremendous interest over the past decade for its enabling combination of high electrical and thermal conductivity and low mechanical compliance and viscosity. Efforts to harness LM in electronics, robotics, and biomedical applications have largely involved methods to encapsulate the liquid so that it can support functionality without leaking or smearing. In recent years, there has been increasing interest in LM “nanocomposites” in which either liquid metal is mixed with metallic nanoparticles or nanoscale droplets of liquid metal are suspended within a soft polymer matrix. Both of these material systems represent an important step towards utilizing liquid metal for breakthrough applications. In this minireview, we present a brief overview of recent progress over the past few years in methods to synthesize LM nanomaterials and utilize them as transducers for sensing, actuation, and energy harvesting. In particular, we focus on techniques for stable synthesis of LM nanodroplets, suspension of nanodroplets within various matrix materials, and methods for incorporating metallic nanoparticles within an LM matrix. 

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4. Metal Matters—Towards the Omnipresence of Metal in Education

   https://doi.org/10.1557/adv.2018.37  

   Tajmel, Tanja; Salzmann, Ingo (January 2018, MRS Advances)

   ABSTRACT For many years, comprehensive data demonstrate a persistent lack of interest in the field of science, technology, engineering and mathematics (STEM) among students in European and North American countries. This lack of interest is regarded as one reason causing underrepresentation of diversity, especially that of female students within the field of STEM. Obviously, students—although possibly highly talented—refrain from choosing STEM careers only because their attention is not sufficiently attracted to STEM at the right time at the right place. In particular, this fact significantly affects the field of material research and, therefore, identifying opportunities for sparking students’ interest in materials is a crucial challenge in the framework of a modern STEM education. Here, we present the outline of the novel project “Metal Matters”, which aims at establishing an interdisciplinary approach to foster the field of materials in education. In essence, our research focusses on the omnipresence of metal as material. By exploring the K-16 continuum, we aim to identify windows of opportunities for raising awareness of the relevance of materials. Our approach is to stimulate interest in the relevance of materials by explicitly promoting metal as a topic across the curriculum. Our project is deliberately not restricted to STEM, but also covers history, society, economy, health, sports, literature, and language. Here, we present one part of the project contrasting the scientific relevance of metal with the students’ ideas about metal. For the present exploration and data collection, we employed a mixed-method design consisting of linguistic frequency analysis of scientific publications as well as the qualitative analysis of students’ written responses and drawings. 

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5. Mixed-Metal Alloying in Hybrid Bronzes

   https://doi.org/10.1021/jacs.4c08960  

   Walte, Anton F; Torres-Cadena, Raúl; Dayaratne, W_Lakna N; Jaffe, Adam (August 2024, Journal of the American Chemical Society)

   We show that substitutional alloying during the aqueous self-assembly of layered organic-templated metal oxides produces single-phase mixed-metal hybrids. Single-crystal X-ray diffraction, bulk elemental analyses, and vibrational and electronic spectroscopies corroborate a solid solution of Mo and W atoms at lattice sites within the two-dimensional metal oxide layers. Mild postsynthetic reduction then introduces relatively delocalized electrons to afford mixed-metal hybrid bronzes. To our knowledge, this represents the first demonstration of mixed-metal alloying in a hybrid metal oxide and a rare example of solid-solution formation at low temperature. We show this approach yields mixed-metal congeners with optical band gaps over 130 meV smaller than those of single-metal analogs, while achieving activation energies (Ea) of conduction as low as 78.4(2) meV. Further, metal substitution appears to tune collective electronic phenomena by suppressing the non-Arrhenius behavior observed for Mo-based hybrids. This work considerably expands the nascent hybrid bronze platform to help address energy-related challenges and fundamental solid-state physical questions. 

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