Structural and cryogenic magnetic properties of rare earth rich RE11Co4In9 (RE = Gd, Dy and Ho) intermetallic compounds.

The crystal structure, magnetic properties and magnetocaloric performances of rare earth rich RE11Co4In9 (RE = Gd, Dy and Ho) intermetallic compounds are investigated systematically in this work. All compounds in this system crystallize in the orthorhombic Nd11Pd4In9-type structure with the Cmmm space group. The stacks of alternate RE and Co/In atomic layers with z = 0, 1 and z = 1/2 along the z-axis constitute the crystal structure. These compounds belong to the REx+yM2yXx family with x = 9 and y = 2, and the ratio of the AlB2-type and CsCl-type fragments in a unit cell is y : x, i.e. 2 : 9. The characteristic of multiple magnetic phase transition is revealed with a low magnetic flux density μ0H of 0.1 T for the present compounds. The ferromagnetic (FM) to paramagnetic (PM) phase transitions of the present compounds around their respective Curie temperatures (TC) are all second order phase transitions (SOPTs). Around the TC of 86, 37 and 20 K for Gd11Co4In9, Dy11Co4In9, and Ho11Co4In9 with a magnetic flux density change Δμ0H of 0–7 T, the values of the maximum magnetic entropy change (−ΔSmaxM) and temperature averaged entropy change (TEC) with 3 K span are 10.95 and 10.93 J kg−1 K−1 for Gd11Co4In9, 4.66 and 4.64 J kg−1 K−1 for Dy11Co4In9, and 12.29 and 12.09 J kg−1 K−1 for Ho11Co4In9, respectively. The corresponding values of relative cooling power (RCP) and refrigerant capacity (RC) are 538.1 and 405.9 J kg−1 for Gd11Co4In9, 213.9 and 165.9 J kg−1 for Dy11Co4In9, and 475.2 and 357.4 J kg−1 for Ho11Co4In9, respectively.