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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 (−ΔS maxM) 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. [ABSTRACT FROM AUTHOR]

The crystal structures, magnetic properties and magneto-caloric effects (MCEs) of RE2Ni2In (RE = Pr, Nd, Dy and Ho) compounds were investigated. The results indicate that Pr2Ni2In and Nd2Ni2In compounds have a tetragonal Mo2FeB2-type structure belonging to the P4/mbm space group and undergo a second-order paramagnetic to ferromagnetic (PM to FM) transition at a Curie temperature (TC) of 7.5 and 10.5 K, respectively, whereas Dy2Ni2In and Ho2Ni2In compounds have an orthorhombic Mn2AlB2-type structure belonging to the space group Cmmm and possess a magnetic transition from PM to antiferromagnetic (AFM) at a Néel temperature TN of 19 and 10.5 K together with a first-order field induced metamagnetic transition, respectively. Moreover, an additional magnetic transition at a lower temperature of around 5.5 K is detected for the Ho2Ni2In compound. A considerable reversible magneto-caloric effect is observed accompanying the magnetic phase transition, and the maximum values of the magnetic entropy change (−ΔS maxM) of the present RE2Ni2In series compounds are determined to be 9.3, 11.5, 6.4 and 11.5 J kg−1 K−1 with a magnetic field change (ΔH) of up to 0–5 T for RE = Pr, Nd, Dy and Ho, respectively. [ABSTRACT FROM AUTHOR]