Seminarium Międzynarodowego Laboratorium Silnych Pól Magnetycznych i Niskich Temperatur PAN
ul. Gajowicka 95, sala seminaryjna (nowy budynek, II piętro)
The physical properties of RNi2, (R = Tb, Dy, Ho, Er): a real candidates for a practical cryogenic refrigerator
Jacek Ćwik
Structural, magnetic and magnetocaloric properties and heat capacity of polycrystalline RNi2, (R = Tb, Dy, Ho, Er) intermetallic compounds were investigated experimentally using by X-ray diffraction, magnetic and heat capacity measurements. High-field magnetocaloric effect of the RNi2 Laves-phase compounds, which show the second-order magnetic phase transition at low temperatures, has been studied experimentally. Both direct and indirect methods were used to find high-field properties of the adiabatic temperature change ΔTad and the magnetic entropy change ΔSmag for selected rare-earh Laves-phase compounds, when they ordered ferromagnetically below 40 K. Experimental data were compared with results of two methods based on a indirect heat capacity, magnetic measurements and direct method. Direct measurements of MCE were performed using the measuring device designed and constructed by the authors. Magnetocaloric parameters for the phase-transition temperature range will be also discussed in the framework of the Landau theory of the second-order phase transitions.
