Factors that drive unequal access to international grain markets
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Generating multi-scale Li-ion battery cathode particles with radial grain architectures using stereological generative adversarial networks
Understanding structure-property relationships of Li-ion battery cathodes is crucial for optimizing rate-performance and cycle-life resilience. However, correlating the morphology of cathode particles, such as in LiNi0.8Mn0.1Co0.1O2 (NMC811), and their inner grain architecture with electrode performance is challenging, particularly, due to the significant length-scale difference between grain and particle sizes. Experimentally, it is not feasible to image such a high number of particles with full granular detail. A second challenge is that sufficiently high-resolution 3D imaging techniques remain expensive and are sparsely available at research institutions. Here, we present a stereological generative adversarial network-based model fitting approach to tackle this, that generates representative 3D information from 2D data, enabling characterization of materials in 3D using cost-effective 2D data. Once calibrated, this multi-scale model can rapidly generate virtual cathode particles that are statistically similar to experimental data, and thus is suitable for virtual characterization and materials testing through numerical simulations. A large dataset of simulated particles with inner grain architecture has been made publicly available.
Study of the protrusion of through-silicon vias in dual annealing-CMP processes for 3D integration
The technology of through-silicon via (TSV) is extensively employed for achieving dense 3D integration. TSV facilitates the electrical interconnection of various layers of integrated circuits in a vertical orientation, thereby allowing for the creation of sophisticated and space-efficient systems that incorporate diverse functionalities. This work reports TSV fabrication with dual annealing-CMP processes to explore the influence of annealing and CMP processes on the evolution of TSV-Cu microstructures and protrusions. The results show that the dual CMP process can effectively reduce protrusion at high temperatures. The Cu protrusion height increased as both the annealing temperature and duration increased, which was consistent with the high-temperature annealing results, whereas a random phenomenon occurred under 250 °C annealing. A phase field model related to the TSV grain size was established to quantitatively explore the grain morphology distribution and thermal-mechanical behavior. The results show that the strain in copper is nonuniform and that the degree of plastic deformation for each grain is closely related to its distribution. The quantity of grains within the TSV is the most important factor for protrusion. As the average grain size increases, the prominence of copper grain protrusions within TSV intensifies, and the anisotropy of the Cu grains becomes more pronounced. The thermal-mechanical behavior strongly depends on the grain orientation near the top of the TSV, which can cause TSV protrusion irregularities. This work may provide more opportunities to design high-performance TSV preparation methods from the viewpoint of the dual CMP process.
Global self-organization of solute induced by ion irradiation in polycrystalline alloys
Most materials are brought into nonequilibrium states during processing and during their service life. Materials for nuclear and space applications, for instance, are continuously exposed to energetic particle irradiation, which is often detrimental to materials’ performance. Here we demonstrate, however, that sustained irradiation can induce self-organization of the microstructure of polycrystalline alloys into steady-state patterns and, in turn, improve their radiation resistance. Using an Al −1.5 at.% Sb alloy as a model system, we show using transmission electron microscopy and atom probe tomography that, for nanocrystalline thin films irradiated at 75 °C with 2 MeV Ti ions to large doses, the microstructure consists of finite-size, self-organized AlSb nanoprecipitates inside the grains and along the grain boundaries. Furthermore, this steady state is independent of the initial microstructure, thus self-healing. Phase field modeling is employed to construct a steady-state phase diagram and extend the experimental results to other alloy systems and microstructures.
The current state, opportunities and challenges for upscaling private investment in biodiversity in Europe
European countries have committed to ambitious upscaling of privately funded nature conservation. We review the status and drivers of biodiversity finance in Europe. By implementing semistructured interviews with 25 biodiversity finance key informants and three focus groups across Europe, we explore opportunities and challenges for upscaling private investment in nature. Opportunities arise from macroeconomic and regulatory changes, along with various technological and financial innovations and growing professional experience. However, persistent barriers to upscaling include the ongoing lack of highly profitable investment opportunities and the multitude of risks facing investors, including political, ecological and reputational risks influencing supply and demand of investment opportunities. Public policy plays the foundational role in creating and hindering these mechanisms. Public policy can create nature markets and investment opportunities, meanwhile agricultural subsidies and poor coordination between public funding sources undermine the supply of return-seeking investment opportunities. Investors demand derisking investments from uncertainties; in part caused by political uncertainty. These markets require profound state intervention to enable upscaling whilst achieving positive ecological outcomes; private investment will probably not upscale without major public policy change and public investment.
Power price stability and the insurance value of renewable technologies
To understand if renewables stabilize or destabilize electricity prices, we simulate European power markets as projected by the National Energy and Climate Plans for 2030 but replicating the historical variability in electricity demand, the prices of fossil fuels and weather. We propose a β-sensitivity metric, defined as the projected increase in the average annual price of electricity when the price of natural gas increases by 1 euro. We show that annual power prices spikes would be more moderate because the β-sensitivity would fall from 1.4 euros to 1 euro. Deployment of solar photovoltaic and wind technologies exceeding 30% of the 2030 target would lower it further, below 0.5 euros. Our framework shows that this stabilization of prices would produce social welfare gains, that is, we find an insurance value of renewables. Because market mechanisms do not internalize this value, we argue that it should be explicitly considered in energy policy decisions.
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