Journal
CHEMISTRY OF MATERIALS
Volume 29, Issue 4, Pages 1613-1622Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.chemmater.6b04729
Keywords
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Funding
- National Science Foundation (NSF) [DMR-1121053]
- National Science Foundation Graduate Research Fellowship Program [1650114]
- NSF MRSEC Program [DMR-1121053]
- NSF MRSEC [DMR-1121053]
- U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences [DE-AC02-06CH11357]
- NSF [CNS-0960316]
- Hewlett-Packard
- NSF
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Alternating cycles of isothermal magnetization and adiabatic demagnetization applied to a magnetocaloric material can drive refrigeration in very much the same manner as cycles of gas compression and expansion. The material property of interest in finding candidate magnetocaloric materials is Delta S-M, their gravimetric entropy change upon application of a magnetic field under isothermal conditions. There is, however, no general method for screening materials for such an entropy change without actually performing the relevant, time- and effort-intensive magnetic measurements. Here we propose a simple computational proxy based on performing nonmagnetic and magnetic density functional theory calculations on magnetic materials. This proxy, which we term the magnetic deformation Sigma(M),, is a measure of how much the unit cell deforms comparing with the relaxed structures with and without the inclusion of spin polarization. Sigma(M) appears to correlate very well with experimentally measured magnetic entropy change values. The proxy has been tested against 33 ferromagnetic materials with known Delta S-M, including nine materials newly measured for this study. It has then been used to screen 134 ferromagnetic materials for which the magnetic entropy has not yet been reported, identifying 30 compounds as being promising for further study. As a demonstration of the effectiveness of our approach, we have prepared one of these compounds and measured its isothermal entropy change. MnCoP, with a T-C of 575 K, shows a maximal Delta S-M of 6.0 J kg(-1) K-1 for an H = S T applied field.
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