The effects of interstitial atoms C and B on magnetic properties and magnetocaloric effect in LaFe11.5Al1.5 compound

• Magnetic properties and MCE of LaFe11.5Al1.5Bx and LaFe11.5Al1.5Cy were studied.
• FM to PM magnetic transition were observed in LaFe11.5Al1.5Bx and LaFe11.5Al1.5Cy.
• Boron or carbon doping can change the magnetic phase transition in LaFe11.5Al1.5.
• Large magnetocaloric in LaFe11.5Al1.5Bx and LaFe11.5Al1.5Cy were observed.

In this paper, the magnetic properties and the magnetic entropy of LaFe11.5Al1.5Bx (x = 0, 0.1, 0.2 and 0.3) and LaFe11.5Al1.5Cy (y = 0.1, 0.2, 0.3, 0.4 and 0.5) compounds have been studied. All the compounds crystallize in the cubic NaZn13-type structure. By introducing interstitial atoms B or C, the magnetic ground state is changed from the antiferromagnetic (AFM) to the ferromagnetic (FM) state. And, the Curie temperature (TC) significantly enhanced with increasing the content of interstitial atoms (B or C). Compared with the obvious variation in Curie temperature, the saturation magnetization (MS) increased slightly. It is worth noting that the magnetic transition changed from weak first-order to second-order with increasing boron or carbon. All the LaFe11.5Al1.5 borides and carbides exhibit a considerable magnetic entropy change, the maximum magnetic entropy change (−ΔSM) reach to 9.6 J/kg K for LaFe11.5Al1.5B0.1 and 10.8 J/kg K for LaFe11.5Al1.5C0.2 under a magnetic field change of 0–5 T.