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1.
Chem Sci ; 13(46): 13774-13781, 2022 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-36544729

RESUMO

The experimental high-throughput (HT) exploration for a suitable solar water splitting photoanode has greatly relied on photoactivity as the sole descriptor to identify a promising region within the searched composition space. Although activity is essential, it is not sufficient for describing the overall performance and excludes other pertinent criteria for photoelectrochemical (PEC) water splitting. Photostability in the form of (photo)electrocatalyst dissolution must be tracked to illustrate the intricate relation between activity and stability for multinary photoelectrocatalysts. To access these two important metrics simultaneously, an automated PEC scanning flow cell coupled to an inductively coupled plasma mass spectrometer (PEC-ICP-MS) was used to study an Fe-Ti-W-O thin film materials library. The results reveal an interrelation between composition, photocurrent density, and element-specific dissolution. These structure-activity-stability correlations can be represented using data science tools like principal component analysis (PCA) in addition to common data visualization approaches. This study demonstrates the importance of addressing two of the most important catalyst metrics (activity and stability) in a rapid and parallel fashion during HT experiments to adequately discover high-performing compositions in the multidimensional search space.

2.
ACS Comb Sci ; 22(11): 641-648, 2020 11 09.
Artigo em Inglês | MEDLINE | ID: mdl-32786322

RESUMO

Combinatorial synthesis and high-throughput characterization of a Ni-Ti-Co thin film materials library are reported for exploration of reversible martensitic transformation. The library was prepared by magnetron co-sputtering, annealed in vacuum at 500 °C without atmospheric exposure, and evaluated for shape memory behavior as an indicator of transformation. Composition, structure, and transformation behavior of the 177 pads in the library were characterized using high-throughput wavelength dispersive spectroscopy (WDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and four-point probe temperature-dependent resistance (R(T)) measurements. A new, expanded composition space having phase transformation with low thermal hysteresis and Co > 10 at. % is found. Unsupervised machine learning methods of hierarchical clustering were employed to streamline data processing of the large XRD and XPS data sets. Through cluster analysis of XRD data, we identified and mapped the constituent structural phases. Composition-structure-property maps for the ternary system are made to correlate the functional properties to the local microstructure and composition of the Ni-Ti-Co thin film library.


Assuntos
Ligas/química , Cobalto/química , Níquel/química , Bibliotecas de Moléculas Pequenas/química , Titânio/química , Técnicas de Química Combinatória , Cristalização , Aprendizado de Máquina , Teste de Materiais , Conformação Molecular , Transição de Fase , Relação Estrutura-Atividade , Temperatura de Transição
3.
ACS Comb Sci ; 14(10): 531-6, 2012 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-22931380

RESUMO

A microgradient-heater (MGH) was developed, and its feasibility as a tool for high-throughput materials science experimentation was tested. The MGH is derived from microhot plate (MHP) systems and allows combinatorial thermal processing on the micronano scale. The temperature gradient is adjustable by the substrate material. For an Au-coated MGH membrane a temperature drop from 605 to 100 °C was measured over a distance of 965 µm, resulting in an average temperature change of 0.52 K/µm. As a proof of principle, we demonstrate the feasibility of MGHs on the example of a chemical vapor deposition (CVD) process. The achieved results show discontinuous changes in surface morphology within a continuous TiO2 film. Furthermore the MGH can be used to get insights into the energetic relations of film growth processes, giving it the potential for microcalorimetry measurements.


Assuntos
Técnicas de Química Combinatória/instrumentação , Calefação/instrumentação , Calorimetria/instrumentação , Ouro/química , Tamanho da Partícula , Propriedades de Superfície , Titânio/química
4.
ACS Comb Sci ; 14(1): 25-30, 2012 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-22126321

RESUMO

For different areas of combinatorial materials science, it is desirable to have multiple materials libraries: especially for irreversible high-throughput studies, like, for example, corrosion resistance testing in different media or annealing of complete materials libraries at different temperatures. Therefore a new combinatorial sputter-deposition process was developed which yields 24 materials libraries in one experiment on a single substrate. It is discussed with the example of 24 Ti-Ni-Ag materials libraries. They are divided based on the composition coverage and orientation of composition gradient into two sets of 12 nearly identical materials libraries. Each materials library covers at least 30-40% of the complete ternary composition range. An acid etch test in buffered-HF solution was performed, illustrating the feasibility of our approach for destructive materials characterization. The results revealed that within the composition range of Ni < 30 at.%, the films were severely etched. The composition range which shows reversible martensitic transformations was confirmed to be outside this region. The high output of the present method makes it attractive for combinatorial studies requiring multiple materials libraries.


Assuntos
Ligas/síntese química , Técnicas de Química Combinatória/métodos , Ensaios de Triagem em Larga Escala/métodos , Bibliotecas de Moléculas Pequenas/síntese química , Ligas/química , Estudos de Viabilidade , Transição de Fase , Bibliotecas de Moléculas Pequenas/química , Propriedades de Superfície
5.
Sci Technol Adv Mater ; 12(5): 054201, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27877428

RESUMO

A high-throughput characterization technique based on digital holography for mapping film thickness in thin-film materials libraries was developed. Digital holographic microscopy is used for fully automatic measurements of the thickness of patterned films with nanometer resolution. The method has several significant advantages over conventional stylus profilometry: it is contactless and fast, substrate bending is compensated, and the experimental setup is simple. Patterned films prepared by different combinatorial thin-film approaches were characterized to investigate and demonstrate this method. The results show that this technique is valuable for the quick, reliable and high-throughput determination of the film thickness distribution in combinatorial materials research. Importantly, it can also be applied to thin films that have been structured by shadow masking.

6.
Sci Technol Adv Mater ; 12(5): 054206, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27877433

RESUMO

Versatile high-throughput characterization tools are required for the development of new materials using combinatorial techniques. Here, we describe a modular, high-throughput test stand for the screening of thin-film materials libraries, which can carry out automated electrical, magnetic and magnetoresistance measurements in the temperature range of -40 to 300 °C. As a proof of concept, we measured the temperature-dependent resistance of Fe-Pd-Mn ferromagnetic shape-memory alloy materials libraries, revealing reversible martensitic transformations and the associated transformation temperatures. Magneto-optical screening measurements of a materials library identify ferromagnetic samples, whereas resistivity maps support the discovery of new phases. A distance sensor in the same setup allows stress measurements in materials libraries deposited on cantilever arrays. A combination of these methods offers a fast and reliable high-throughput characterization technology for searching for new materials. Using this approach, a composition region has been identified in the Fe-Pd-Mn system that combines ferromagnetism and martensitic transformation.

7.
Nat Mater ; 5(4): 286-90, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16518396

RESUMO

Reversibility of structural phase transformations has profound technological implications in a wide range of applications from fatigue life in shape-memory alloys (SMAs) to magnetism in multiferroic oxides. The geometric nonlinear theory of martensite universally applicable to all structural transitions has been developed. It predicts the reversibility of the transitions as manifested in the hysteresis behaviour based solely on crystal symmetry and geometric compatibilities between phases. In this article, we report on the verification of the theory using the high-throughput approach. The thin-film composition-spread technique was devised to rapidly map the lattice parameters and the thermal hysteresis of ternary alloy systems. A clear relationship between the hysteresis and the middle eigenvalue of the transformation stretch tensor as predicted by the theory was observed for the first time. We have also identified a new composition region of titanium-rich SMAs with potential for improved control of SMA properties.


Assuntos
Biofísica/métodos , Algoritmos , Ligas , Materiais Biocompatíveis , Cobre/química , Corrosão , Ligas Dentárias/química , Elasticidade , Compostos Férricos/química , Temperatura Alta , Magnetismo , Teste de Materiais , Modelos Estatísticos , Modelos Teóricos , Níquel/química , Óxidos/química , Propriedades de Superfície , Titânio/química , Difração de Raios X
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