20.06.2016 von 17:15 bis 18:45
Institut für Materialwissenschaften, Kaiserstraße 2, 24143 Kiel, Raum: Geb. D, "Aquarium"
Titel: Compatibility, hysteresis and the direct conversion of heat to electricity
Abstract: Big first order phase transformations in solids can be highly
reversible, if the lattice parameters are “tuned” to satisfy certain
relations that promote the compatibility between phases. We
outline the basic theory behind this tuning and give examples of
recently discovered alloys. Some of these alloys have thermal
hysteresis as low as 0.2 C despite having an 8%
transformation strain. The lowered hysteresis correlates with the
reversibility of the transformation under repeated cycling, and links to
important discoveries madein Kiel. We use this kind of
tuning, together with the lattice parameter sensitivity of magnetic
properties and the presence of a jump of lattice parameters at the
phase transformation, to find some interesting new
multiferroic Heusler alloys: briefly, multiferroism by reversible phase
transformation. These alloys can be used in diverse ways for
the direct conversion of heat to electricity, and provide interesting
possible ways to recover the vast amounts of energy stored on earth at
small temperature difference.
Prof. Quandt
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