Magnetism and magnetocaloric effects in tetragonal structure of RE5Ni2Sb (R = Er, Ho) compounds

•R5Ni2Sb (R = Er, Ho) polycrystalline samples were synthesized, and magnetic anomalies below the magnetic transition temperature were reported for the first time.•R5Ni2Sb (R = Er, Ho) compounds with field-induced metamagnetic transition behavior under a magnetic field were observed.•The maximum magnetic entropy changes of Er5Ni2Sb and Ho5Ni2Sb are 9.8 J/kg K and 10.6 J/kg K under a varying magnetic field of 0–5 T, respectively. In this work, the RE5Ni2Sb (RE = Er, Ho) compounds with tetragonal structure were successfully synthesized and the magnetism, magnetic phase transition and magnetocaloric effects were investigated. It was demonstrated that antiferromagnetic interaction undergoes a field-induced metamagnetic transition from antiferromagnetism to ferromagnetism in RE5Ni2Sb (RE = Er, Ho) under a magnetic field higher than 3 T. Moreover, the Er5Ni2Sb and Ho5Ni2Sb undergo an antiferromagnetic to paramagnetic magnetic phase transition at approximately 18 K and 25 K, and exhibit considerable magnetocaloric effects. The maximum magnetic entropy changes are 9.8 J/kg K and 10.6 J/kg K under varying magnetic fields of 0–5 T. Therefore, the large reversible MCE under low magnetic field change indicates the potential application of RE5Ni2Sb (RE = Er, Ho) in hydrogen liquefaction magnetic refrigerators. This work investigates the synthesis, magnetism, and magnetothermal effects of R5Ni2Sb (R = Er, Ho) compounds. The R5Ni2Sb (R = Er, Ho) compounds have been demonstrated for the first time to have a potential application as magnetic refrigeration materials.