What is combinatorial materials science?
The goal of combinatorial materials science is high-throughput, high quality data generation to facilitate rapid materials discovery, optimization, development, and commercialization. There are three essential steps:
Make it. Synthesis of combinatorial thin film library in which the elemental composition varies continuously and predictably across the library sample.
Measure it. Rapid, local measurements of the properties of interest.
Inform and Iterate. Robust data handling, data curation and analysis techniques to convert experimental data into knowledge. This can be for design of the next experiment, as well as informing computational models.
What is it good for?
Applications-driven. We are exclusively interested in materials for which there is an industrial or government-agency need and application.
Model validation. Computer simulations of important advanced materials benefit from experimental input and validation, such as the self-consistent, high density datasets generated by combinatorial methods.
What are some example problems?
We are interested in materials for energy applications, as well as facilitating industrial process development.
Corrosion-resistant alloys. Per a 2002 NACE study the estimated direct cost of metallic corrosion in the U.S. is roughly 3% of the US GDP impacting the chemical industry, the automotive industry, infrastructure, and power generation. Coatings that are stable, substrate compatible, corrosion resistant, adherent, and high hardness offer an opportunity to emphasize developing bulk alloys with the required structural properties (e.g. Mg-alloys for vehicle lightweighting) separately from environmental considerations.
Materials for storing hydrogen. As of 2016, 3 automakers (Hyundai, Honda, and Toyota) were offering fuel cell powered hydrogen cars for sale in the U.S., specifically in California. New materials are still required for onboard storage and to support hydrogen fueling stations, in order to drive vehicle and hydrogen refueling costs down. For fueling station applications, new methodologies need to be developed for identifying potential materials that match volumetric, thermodynamic and cost targets.
Thermoelectrics. Thermoelectric phenomena enable the solid-state inter-conversion of thermal and electrical energy. Materials that efficiently convert heat into useful energy are desirable for applications such as automotive engine waste heat recovery, where their use improves fuel efficiency and decreases CO2 emissions. In the example shown, the thermoelectric power factor is plotted as a function of composition for La and Sr substituted Ca3Co4O9, with a "sweet spot" close to (Ca2Sr0.7La0.3)Co4O9.
Materials for thermochromic smart windows that automatically darken on hot days. Vanadium dioxide (VO2) undergoes a thermochromic phase transition from a transparent state (low temperature) to a reflective state (high temperature); the transition temperature is in the range of 10ºC to 70ºC, depending on substitutional impurities such as tungsten.
Thin film 'working' phase diagrams. Thin films are technologically important for many industries, but are often non-equilibrium and hence, published equilibrium bulk phase diagrams are of limited use in process development. Combinatorial synthesis enables high-throughput exploration of composition-microstructure-process parameter space.