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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Dirac node engineering and flat bands in doped Dirac materials
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Invertible optical nonlinearity in epsilon-near-zero materials
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Superconductivity of anomalous pseudospin in nonsymmorphic materials
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Structural spillage: An efficient method to identify noncrystalline topological materials
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General Principles for the Nonequilibrium Relaxation of Populations in Quantum Materials
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Superconductivity near a Ferroelectric Quantum Critical Point in Ultralow-Density Dirac Materials
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Performance Evaluation of Image Super-Resolution for Cavity Detection in Irradiated Materials
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A Static-Sample Magnetometer for Characterizing Weak Magnetic Materials
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Preventing mussel adhesion using lubricant-infused materials
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Machine learning approaches for elastic localization linkages in high-contrast composite materials
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Advances in Multimodal Characterization of Structural Materials
The myriad detectors and instruments now available for materials characterization provide researchers with an ever-growing suite of tools to probe material behavior. Progress in the development of instrumentation and workflows that enable the collection, and leverage the potential, of various data modalities have provided novel insights into material behavior. Using data across multiple length scales, or performing complementary analyses of in situ and ex situ data, can help reveal a more complete picture of dynamic processes or material structure. However, the accurate combination, or fusion, of these disparate data modalities presents new challenges. Differences in resolution, as well as the varying length scales at which physical phenomena are exploited to generate these data, necessitate novel approaches to accurately interpret and combine these data. Furthermore, the papers within this special topic focus on the collection and fusion of multimodal data to better understand structural materials. From new frameworks and workflows for data segmentation and analysis, process monitoring, enhancing simulations, or interrogating mechanical response, these papers reveal the potential benefits of utilizing multimodal data.
Analysis of the Frequency and Diversity of 1,3-Dialkylimidazolium Ionic Liquids Appearing in the Literature
The hypothetical assertion that there are potentially millions of ionic liquids (ILs) can be validated using basic knowledge of IL precursors and simple calculations. While it is an interesting thought exercise to ponder the possibilities of ILs, it is important to investigate how many discrete ILs (i.e., unique cation and anion pairings) have actually been synthesized and reported in the literature. A complete analysis of all ILs is a daunting task, especially if the definition of what constitutes an IL is broad. Nonetheless, insight can be gained into the use of ILs over the past ~20 years from a focused analysis of systematically varied 1,3-dialkylimidazolium-based ILs (i.e., [R 1 R 2 im][X], where R 1 and R 2 are n-alkyl chains and X is either a halide or molecular anion). This family of ILs includes many of the most widely used and most thoroughly studied IL substances, including 1-butyl-3-methylimidazolium hexafluorophosphate ([C 4 mim][PF 6 ]) and 1-ethyl-3-methylimidazolium bistriflimide ([C 2 mim][Tf 2 N]). Using data retrieved from SciFinder searches, we analyzed the variety and frequency of 1,3-dialkylimidazolium-based ILs appearing in the literature. Our analysis reveals that there is a relatively large number of simple 1,3-dialkylimidazolium cations which have not yet been synthesized. Our findings indicate that despite the broad possibilities of IL structures available, there are but a handful of ILs that are commonly used and studied. Within the 1248 [R 1 R 2 im][X] ILs studied, there were only 12 cations extensively used, which included [R 1 R 2 im] + (R 1 = C 1 and R 2 = C 1 –C 12 ). Of the 16 anions studied, only 5, including [BF 4 ] – , [Cl] – , [PF 6 ] – , [Tf 2 N] – , and [Br] – , were used significantly. Thus, it appears that although ILs can be used as designer solvents with task-specific properties, there is a small default subset of ILs, which are “go-to” or “one-size-fits-all.” Here, we rationalize the current state of the IL landscape in terms of the historical perceptions (and misconceptions) around ILs, familiarity, availability and cost of starting materials, commercial availability of ILs, and the motivations from which researchers choose to synthesize and characterize new ILs.
Zero thermal expansion and semiconducting properties in PbTiO 3 –Bi(Co, Ti)O 3 ferroelectric solid solutions
Zero thermal expansion (ZTE) behavior is rare but important for both fundamental studies and practical applications of functional materials. Up to now, most available ZTE materials are either electrical insulating oxides or conductive metallic compounds. Very few ZTE materials exhibit the semiconductor feature. Here we report a ZTE in semiconducting ferroelectric of 0.6PbTiO 3 -0.4Bi(Co 0.55 Ti 0.45 )O 3-δ . Its unit cell volume exhibits a negligible change over a broad temperature range from room temperature to 500 °C. The ZTE is supposed to be correlated with the spontaneous volume ferroelectronstriction. Intriguingly, the present ZTE material also exhibits the semiconducting characteristic accompanied by negative temperature coefficient of resistance. The mechanism of electric conduction is attributed to the electronic hopping from one ionic (Ti 3+ ) to another (Ti 4+ ). The semiconductor nature has also been confirmed by the noticeable visible-light absorption with the relative lower band-gap (E g ) value of 1.5 eV, while ferroelectric property can be well maintained with large polarization. The first-principles calculations reveal that the drastically narrowed E g is related to the Co-Ti substitution. Finally, the present multifunctional material containing ZTE, semiconducting and ferroelectric properties is suggested to enable new applications such as the substrate for solar conversion devices.