High-throughput Combinatorial Technique Research Articles

Combinatorial study of thermal stability in ternary nanocrystalline alloys

Nanocrystalline alloys can be stabilized through selective grain boundary segregation of specific solute element additions. Increasing attention is being paid to ternary and higher order systems, where complex interactions govern segregation. To efficiently study the large composition spaces of such systems, we apply a high-throughput combinatorial technique revealing nanocrystalline stability through composition-grain-size maps. We compare two systems with distinct binary and ternary alloy interactions: In Pt–AuAg both binaries are expected to be stable, whereas in Pt–AuPd the Pt–Pd binary is unstable and Au-induced co-segregation of Pd was previously reported. For ternary Pt–AuAg we find excellent thermal stability throughout. The Pt–AuPd system, by contrast, divides into an unstable regime, where Pd solute dominates and precipitates, and a stable regime, where Au solute dominates and retains Pd in the grain boundary. Overall, by combining current theory and the introduced combinatorial approach, stable multicomponent nanocrystalline composition spaces can be rapidly determined.

High-throughput combinatorial chemical bath deposition: The case of doping Cu (In, Ga) Se film with antimony

The conventional methods for designing and preparing thin film based on wet process remain a challenge due to disadvantages such as time-consuming and ineffective, which hinders the development of novel materials. Herein, we present a high-throughput combinatorial technique for continuous thin film preparation relied on chemical bath deposition (CBD). The method is ideally used to prepare high-throughput combinatorial material library with low decomposition temperatures and high water- or oxygen-sensitivity at relatively high-temperature. To check this system, a Cu(In, Ga)Se (CIGS) thin films library doped with 0–19.04 at.% of antimony (Sb) was taken as an example to evaluate the regulation of varying Sb doping concentration on the grain growth, structure, morphology and electrical properties of CIGS thin film systemically. Combined with the Energy Dispersive Spectrometer (EDS), X-ray Photoelectron Spectroscopy (XPS), automated X-ray Diffraction (XRD) for rapid screening and Localized Electrochemical Impedance Spectroscopy (LEIS), it was confirmed that this combinatorial high-throughput system could be used to identify the composition with the optimal grain orientation growth, microstructure and electrical properties systematically, through accurately monitoring the doping content and material composition. According to the characterization results, a Sb2Se3 quasi-liquid phase promoted CIGS film-growth model has been put forward. In addition to CIGS thin film reported here, the combinatorial CBD also could be applied to the high-throughput screening of other sulfide thin film material systems.

Thermoelectric properties of the LaCoO3-LaCrO3 system using a high-throughput combinatorial approach

A combinatorial film of the LaCo1-xCrxO3 system was fabricated using the LaCoO3 and LaCrO3 targets at the NIST Pulsed Laser Deposition (PLD) facility. As the ionic size of Cr3+ is greater than that of Co3+, the unit cell volume of the series increases with increasing x. Using a custom screening tool, the Seebeck coefficient of LaCo1-xCrxO3 approaches a measured maximum of 286 μV/K, near to the cobalt-rich end of the film library (with x ≈ 0.49). The resistivity value increases continuously with increasing x. The measured power factor, PF, of this series, which is related to the efficiency of energy conversion, also exhibits a maximum at the composition of x ≈ 0.49, which corresponds to the maximum value of the Seebeck coefficient. Our results illustrate the efficiency of applying the high-throughput combinatorial technique to study thermoelectric materials.

Discovery via Integration of Experimentation and Modeling: Three Examples for Titanium Alloys

One key aspect of any integrated computational materials engineering approach is the integration of experiments that provide critical information for the modeling activities. This article describes, using case studies, three examples of critical experiments that have been conducted in an integrated fashion with modeling activities for titanium alloys, providing valuable information in an accelerated manner. The first has been used to identify key microstructural features associated with fracture toughness in Ti-6Al-4V and integrates artificial neural networks and various experimental techniques. The second is associated with defect accumulation in highly constrained titanium structures and integrates a highly innovative characterization technique (precession electron diffraction) and dislocation dynamics. The third is a high-throughput combinatorial technique to understand the oxidation behavior of titanium alloys and couples the experimental effort with the CALPHAD approach.

Combinatorial Discovery and Optimization of a Complex Oxide with Water Photoelectrolysis Activity

A ternary oxide containing cobalt, aluminum, and iron and not previously known to be active for the photoelectrolysis of water was identified using a high throughput combinatorial technique. The technique involves ink jet printing overlapping patterns of oxide precursors onto fluorine-doped tin oxide conductive glass substrates. Subsequent pyrolysis yields patterns of mixed oxide compositions that were screened for photoelectrolysis activity by scanning a laser over the material while it was immersed in an electrolyte and mapping the photocurrent response. The composition and optimum thickness for photoelectrochemical response of the newly identified material was further refined using quantitative ink jet printing. Chemical analysis of bulk and thin film samples revealed that the material contains cobalt, aluminum, and iron in a Co3O4 spinel structure with Fe and Al substituted into Co sites with a nominal stoichiometry of Co3−x−yAlxFeyO4 where x and y are about 0.18 and 0.30, respectively. The material is a p-type semiconductor with an indirect band gap of around 1.5 eV, a value that is nearly ideal for an efficient single photoelectrode for water photoelectroylsis. Photoelectrochemical measurements indicate that the onset of hydrogen evolution is about 0.9 V positive of the thermodynamic value but the photocurrent is limited by slow kinetics for hydrogen evolution.

An optical method to determine the thermodynamics of hydrogen absorption and desorption in metals

Hydrogenography, an optical high-throughput combinatorial technique to find hydrogen storage materials, has so far been applied only to materials undergoing a metal-to-semiconductor transition during hydrogenation. We show here that this technique works equally well for metallic hydrides. Additionally, we find that the thermodynamic data obtained optically on thin Pd–H films agree very well with Pd–H bulk data. This confirms that hydrogenography is a valuable general method to determine the relevant parameters for hydrogen storage in metal hydrides.

Integrating a Raman Microscope into the Workflow of a High-Throughput Crystallization Laboratory

Optimizing the choice of polymorphs of an active pharmaceutical ingredient (API) has become a significant step in the drug development process. High-throughput combinatorial techniques have been developed to reduce the time required to identify and select the best form of an API. A very important part of the high-throughput crystallization (HTC) workflow is reliable integration of information produced by various analytical instruments and easy access to the information by multiple scientists. Raman spectroscopy has become one of the key analytic techniques used to differentiate between the polymorphs and salts of the API. A Raman microscope has been integrated into an HTC workflow analyzing samples in a 96-well microtiter plate. The control software on the Raman instrument has been modified to open a text file prepared by the HTC software suite to initiate semiautomated analysis of the samples in a specified well plate. All of the data acquisition and spectral analysis is performed by the Raman instrument including various chemometric techniques for classifying and clustering the samples based on their Raman spectra. The final analytical results and spectra are then formatted and saved for easy entry into the central database (SQL LIMS). An HTC software suite has been developed in-house for the HTC laboratory, which includes routines for display and manipulation of the combined information.