LAUSR

Abstract Nd2Fe17−xCox ( x = 0 , 1 , 2 , 3 , 4 ) intermetallic compounds, obtained under arc-melting conditions, have been investigated by means of X-ray diffraction analysis (XRD), Mossbauer spectrometry and magnetic measurements. The Rietveld refinement revealed that the sample is a pure compound with rhombohedral Th2Zn17-type structure ( R 3 ¯ m space group) with the following lattice parameters: a = 8.5792 (2) A, c = 12.4615 (2) A. Using Mossbauer spectrometry analysis coupled with structural consideration we have unambiguously determined the cobalt atoms preferred inequivalent crystallographic site. Nd2Fe17 show an increase of 3.5 T in their weighted average hyperfine fields upon cobalt substitution. Whatever the cobalt content, the hyperfine field of these compounds follow this sequence H hf { 6 c } > H hf { 9 d } > H hf { 18 f } > H hf { 18 h } . The magnetic measurements showed that the Curie temperature increases with the Co content. The magnetic entropy change ( Δ S M ) was estimated from isothermal magnetization curves and it increases from 3.35 J/Kg K for x = 0 to 5.83 J/Kg K for x = 2 at μ 0 H = 1.6 T . The relative cooling power (RCP) is in the range of 11.6 J/kg ( x = 0 ) and 16 J/kg ( x = 2 ).