|Title:||The Giant inverse magnetocaloric effect in Ni-Mn-Sn alloys||Other Titles:||Der magnetokalorische Effekt in Ni-Mn-Sn Legierungen||Language:||English||Authors:||Frischauf, Klaus||Qualification level:||Diploma||Keywords:||magnetokalorischer Effekt
|Advisor:||Sauerzopf, Franz||Issue Date:||2019||Number of Pages:||94||Qualification level:||Diploma||Abstract:||
The giant inverse magnetocaloric effect was measured for four different NiMnSn alloys. Their content of elements was varied by only 1-2% respectively, but showed big changes to the phase transition temperatures and magnetic entropy change. It was expected that an increase in valence electrons per atom (e/a) and a decrease in the size of the unit cell (Vcell) would increase their phase transition temperaturesrespectively. Increasing the amount of Ni by 1 % at cost of Mn, increased the transition temperatures but also slightly reduced the magnetic entropy change (SM) and refrigerant capacity (RC). Introducing 2% of Si or Ge on cost of Sn reduced Vcell, as confirmed with XRD measurements. This is supposed to hold e/a constant, but is not yet confirmed experimentally. Si and Ge doping strongly decreased the RC and significantly shifted the transition temperatures down and up, respectively. This thesis contains information about their lattice constants, martensitic and austenitic phase transition temperatures, Curie temperatures, isothermal magnetization measurements, critical exponents, magnetic entropy change and resulting refrigerant capacities.
|Library ID:||AC15413999||Organisation:||E141 - Atominstitut||Publication Type:||Thesis
|Appears in Collections:||Thesis|
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