Nanomaterials for Magnetic RefrigerationStephanie L. Brock, Wayne State University, DMR 1064159

Air conditioning and refrigeration is a part of daily life, with ac consuming 5%, and commercial refrigeration taking up to 20%, of our energy output. The conventional process of refrigeration (gas compression and expansion) has limited efficiency, and the refrigerants are ozone-depleting Greenhouse gases, raising concerns whenever inevitable leaks arise. A more energy efficient and environmentally friendly process is magnetic refrigeration, where application of a magnetic field to a magnetocaloric (MC) material results in heat emission, and removal of that field results in heat absorption, effectively acting as a heat pump. Traditional MC materials are based on the rare-earth metal Gd, which suffers from poor efficiency near room temperature and is prohibitively expensive. In NSF-supported research, we demonstrate that nanoparticle forms of compounds based on earth-abundant Mn may be suitable MC materials for near-room temperature magnetic refrigeration.

Just add phosphorus! MnAs nanoparticles (imaged above, left) with <3% of P exhibit programmable magnetic properties. While individual particles exhibit sharp magnetic transitions at different temperatures depending on how much P they have, as an aggregate sample, the magnetic transition is smeared over a large range of temperature, with the population of “magnetized” particles at any one temperature “programmed” by the processing history of the sample. This, combined with the low thermal hysteresis associated with their small particle size, makes them promising for magnetic refrigeration cycling over a practical range of temperatures. Samar Hammoud (above, right), an undergraduate Chemistry major, is working hard to control the way P is incorporated to further augment performance.

Metro Detroit girls participate in GO-GIRLs Go Material Girls, a one-day outreach event where they made liquid crystals (LCs), created LC thermometers, brainstormed ways to use LCs to solve societal problems, and toured state-of-the-art materials characterization facilities at Wayne State University. We finished with a game of “Materials Bingo” to test the knowledge gained over the course of the day and a survey to assess the efficacy of the program in increasing awareness of STEM.

GO-GIRLs Go Material Girls (G3MG)Stephanie L. Brock , Wayne State University, DMR 1064159

As part of a comprehensive program at Wayne State University to direct girls into Science, Technology, Engineering, and Math (STEM) disciplines, GO-GIRLs Go Material Girls, a 1-day outreach event for Detroit area girls in 8-12th grades, was developed and implemented for the first time on May 5th, 2012. The module incorporated a brief college-style lecture, a wet-lab focused on liquid crystal synthesis, and a tour of the materials facilities at WSU. The lab content was developed and tested with the help of an undergraduate researcher, David Miga and graduate student Asha Bandara. In 2013, a problem-solving activity, in which the girls thought up ways to use liquid crystals to address problems in transportation, medicine and national security, was added. In this most recent event, ca 40 girls participated, led by 25 volunteers from WSU Chemistry.

Gaining Options-Girls Investigate Real Life

G3MG 2013