Magnetic properties and magneto-caloric effect in pseudo-binary intermetallic (Ce,R)2Fe17 compounds (R = Y, Pr and Dy)
文摘
We have synthesized three pseudo-binary (Ce,R)2Fe17 intermetallic alloys, where cerium has been partially substituted by R = Y, Pr and Dy, with the aim of tuning the Curie temperature (between 253 and 273 K) for obtaining the maximum magneto-caloric response of the alloys just below room temperature. The analysis of the x-ray powder diffraction patterns show that the three samples crystallize in the rhombohedral Th2Zn17-type crystal structure (space group ). We report the temperature dependence of the isothermal magnetic entropy change, ΔSM(T), the magnetic field dependence of its maximum value, ΔSMmax(H), and the relative cooling power around the second-order magnetic transition for magnetic field changes μ0ΔHmax = 5 T. The collapse of the normalized ΔSM(θ)/ΔSMmax vs. temperature (where θ is a rescaled temperature) into a single master curve allows the extrapolation of ΔSM(T) curves for higher magnetic field changes, and/or the estimation of the temperature dependence of the magnetic entropy for other 2:17 pseudo-binary compounds. The lower values of ΔSMmax compared with those of the R2Fe17 compounds with R = Pr or Nd are explained in terms of the decrease of the saturation magnetization. The magnetic field dependence of the ΔSMmax indicates that only Pr1.5Ce0.5Fe17 alloy roughly follows a mean-field behaviour.