Session T10: Invited Session: Earth-Abundant Materials for Critical Technologies

An Overview of Rare Earth Science and Technology

Currently rare earth science and technology is robust: this includes all the major branches of science -- biochemistry, chemistry, materials and physics. There are, however, currently some anomalies and distortions especially in the technology and applications sector of the rare earth field, which is caused by the dominance of China on the sales of rare earths and rare earth containing products. For the past 5 to 10 years $\sim $95{\%} of rare earths utilized in commerce came from China. Although Chinese actions have lead to sudden and large price spikes and export embargoes, the rare earths are still available but at a higher cost. The start up of production in 2011 at mines in the USA and Australia will alleviate this situation in about two years. Basic and applied research on the condensed matter physics/materials science has hardly been impacted by these events, but new research opportunities are opening up especially with regard to the USA's military and energy security. Magnets seems to be the hottest topic, but research on battery materials, phosphors and catalysts are also (or should be) strongly considered.   

Replacing critical rare earth materials in high energy density magnets

High energy density permanent magnets are crucial to the design of internal permanent magnet motors (IPM) for hybride and electric vehicles and direct drive wind generators. Current motor designs use rare earth permanent magnets which easily meet the performance goals, however, the rising concerns over cost and foreign control of the current supply of rare earth resources has motivated a search for non-rare earth based permanent magnets alloys with performance metrics which allow the design of permanent magnet motors and generators without rare earth magnets. This talk will discuss the state of non-rare-earth permanent magnets and efforts to both improve the current materials and find new materials. These efforts combine first principles calculations and meso-scale magnetic modeling with advance characterization and synthesis techniques in order to advance the state of the art in non rare earth permanent magnets. The use of genetic algorithms in first principle structural calculations, combinatorial synthesis in the experimental search for materials, atom probe microscopy to characterize grain boundaries on the atomic level, and other state of the art techniques will be discussed. In addition the possibility of replacing critical rare earth elements with the most abundant rare earth Ce will be discussed.   

Solar to Fuel Conversion with Earth Abundant Materials

Studies in the Nocera group have led to the creation of a new earth-abundant catalyst that captures many of the functional elements of photosynthesis and in doing so provides a highly manufacturable and inexpensive method to effect a carbon-neutral and sustainable method for solar storage - solar fuels from water-splitting. This discovery enables an inexpensive 24/7 solar energy system for the individual, a capability that is attractive in the underdeveloped as well as the developed world.   

Organic-inorganic hybrid materials for energy efficiency

Quantum dot (QD) semiconductor nanocrystals are unique hybrid materials that have been considered in a broad range of energy production and energy efficiency applications including LEDs, displays, lighting and solar cells. In their photoluminescent mode of operation, QDs are currently in lighting products, and have the promise to be in liquid crystal display products in the near future, in both cases offering energy efficiency gains in the range of 25-40{\%}. In electroluminescent mode, quantum dot light emitting devices (QLEDs) are an emerging class of thin-film hybrid organic-inorganic structures that can potentially achieve best-in-class performance amongst large-area emissive light sources. Indeed, efficiencies which double that of the most efficient OLEDs have been suggested. The hybrid nature of these materials offers the key design parameters that have enabled QD technology to reach market in lighting products, and promises to soon revolutionize the display industry.   

Photovoltaic devices using inexpensive, abundant inorganic materials: experiences with copper zinc tin sulfide (CZTS)

For photovoltaics to be able to contribute a significant percentage of global electricity, we ideally desire a cheap, efficient, safe, and abundant solar cell that can be treated more as a construction material than as a delicate semiconductor. We are not quite there yet, though thin film polycrystalline solar cells on cheap substrates represent a potential way to accomplish this objective. I will describe some of the requirements for a solar cell with this application objective, describe some of the challenges when we desire to transform a ``polycrystalline,'' ``mineral-like'' absorber into an efficient p-n junction solar cell, and in this context will describe our results with the kesterite compound copper zinc tin sulfide (CZTS).