Fe 67 Co 18 B 15 amorphous thin films were sputter deposited on glass substrates under a uniform applied magnetic field. The films exhibit excellent soft-magnetic properties of 4πMs∼17.5 kG, Hc∼0.3 Oe, and Hk (anisotropy field) ∼22 Oe. The ultra-high-frequency performance on these films was studied and the relative permeability μ′ is shown to be as high as ∼740 and almost constant to at least 1 GHz. The combination of high 4πMs and relatively high Hk in these films is believed to be partly responsible for the excellent ultra-high-frequency behavior. The soft-magnetic properties of these films show a strong dependence on the film deposition bias voltage, which presumably changes the microstructure of the films and the related magnetic anisotropy.
Sputter codeposition of platinum and tantalum is used to generate catalyst libraries of Pt1−xTax with 0.05< x <0.9. Extensive characterization of the libraries by high-energy X-ray diffraction reveals the presence of several ordered intermetallic phases as a function of composition and deposition conditions. Assessment of the activity toward the oxidation of methanol and formic acid is achieved through a fluorescence-based parallel screening, followed by detailed testing of the most promising catalysts. Correlations among the electrochemical results, the inferred phase fields and X-ray photoelectron spectroscopy characterization provide an understanding of the catalytically active surface and highlight the utility of composition spread thin films in catalyst research. The observations suggest that the interaction between Pt and Ta suboxides is important and enhances the catalytic activity of Pt.
Microcalorimeters have been used to measure the temperature dependence of the specific heat ${C}_{p}(T)$ of amorphous ${R}_{x}{\mathrm{Fe}}_{100\ensuremath{-}x}$ $(R=\mathrm{Gd},\phantom{\rule{0ex}{0ex}}\mathrm{Tb})$ thin films prepared by both sputtering and e-beam coevaporation. $a\ensuremath{-}{\mathrm{Tb}}_{x}{\mathrm{Fe}}_{100\ensuremath{-}x}$ films possess large randomly oriented local magnetic anisotropy and large exchange coupling; they are considered random-anisotropy magnets. By varying growth temperature and by annealing, films of the same composition but with very different macroscopic anisotropy constant ${K}_{u}$ were prepared and studied. ${K}_{u}$ reflects the degree of nonrandomness in the local anisotropy axis directions. $a\ensuremath{-}{\mathrm{Gd}}_{x}{\mathrm{Fe}}_{100\ensuremath{-}x}$ films possess negligible local and macroscopic anisotropy. All samples show a relatively sharp peak in ${C}_{p}(T)$ at the Curie temperature ${T}_{c}$ determined by magnetization measurements, indicative of a phase transition, independent of the magnitude of ${K}_{u}.$ Effective critical exponents of $\ensuremath{\alpha}={\ensuremath{\alpha}}^{\ensuremath{'}}=\ensuremath{-}0.6$ to -0.7 and a critical amplitude ratio of 1.5--2.5 are measured for reduced temperatures down to 0.02. Nearly all possible magnetic entropy is developed below ${T}_{c},$ unlike what is seen in spin glasses. Increased growth or annealing temperature causes a small but systematic increase in ${T}_{c},$ in the inverse high-field susceptibility \ensuremath{\chi} and in the homogeneity of the sample; ${K}_{u}$ by contrast increases with growth temperature, but decreases with annealing.
Autonomous experimentation enabled by artificial intelligence (AI) offers a new paradigm for accelerating scientific discovery. Non-equilibrium materials synthesis is emblematic of complex, resource-intensive experimentation whose acceleration would be a watershed for materials discovery and development. The mapping of non-equilibrium synthesis phase diagrams has recently been accelerated via high throughput experimentation but still limits materials research because the parameter space is too vast to be exhaustively explored. We demonstrate accelerated synthesis and exploration of metastable materials through hierarchical autonomous experimentation governed by the Scientific Autonomous Reasoning Agent (SARA). SARA integrates robotic materials synthesis and characterization along with a hierarchy of AI methods that efficiently reveal the structure of processing phase diagrams. SARA designs lateral gradient laser spike annealing (lg-LSA) experiments for parallel materials synthesis and employs optical spectroscopy to rapidly identify phase transitions. Efficient exploration of the multi-dimensional parameter space is achieved with nested active learning (AL) cycles built upon advanced machine learning models that incorporate the underlying physics of the experiments as well as end-to-end uncertainty quantification. With this, and the coordination of AL at multiple scales, SARA embodies AI harnessing of complex scientific tasks. We demonstrate its performance by autonomously mapping synthesis phase boundaries for the Bi$_2$O$_3$ system, leading to orders-of-magnitude acceleration in establishment of a synthesis phase diagram that includes conditions for kinetically stabilizing $\delta$-Bi$_2$O$_3$ at room temperature, a critical development for electrochemical technologies such as solid oxide fuel cells.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInvestigation of ternary transition-metal nitride systems by reactive cosputteringR. B. Van Dover, B. Hessen, D. Werder, C. H. Chen, and R. J. FelderCite this: Chem. Mater. 1993, 5, 1, 32–35Publication Date (Print):January 1, 1993Publication History Published online1 May 2002Published inissue 1 January 1993https://pubs.acs.org/doi/10.1021/cm00025a010https://doi.org/10.1021/cm00025a010research-articleACS PublicationsRequest reuse permissionsArticle Views184Altmetric-Citations13LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
We show a systematic trend of x-ray photoelectron binding energy shifts for Zr- and Hf-silicates, which are related to the composition of the films. The binding energy for the core photoelectrons can shift by up to 2 eV, depending on the relative electronegativities of the second nearest-neighbor elements. Understanding these shifts helps determine the underlying local electronic and chemical nature of the silicate network. Furthermore, we explain how charge at the dielectric-semiconductor interface can lead to shifts in the measured Si 2p peak binding energy by as much as 1 eV. The direction and magnitude of the binding energy shift can be used to determine the sign and density of the charge at the interface.
