The effect of boron doping on crystal structure, magnetic properties and magnetocaloric effect of DyCo2

• The discrepancy between the ZFC and FCC curves of DyCo2Bx is enhanced in the B doped samples, while the frequency dependence of the ac magnetic susceptibility is depressed.
• The Curie temperature, coercivity and viscosity of DyCo2Bx are increased by B doping
• The magnetic transition nature of the B doped samples is changed from first order to second order, leading to the decrease of magnetic entropy change. However, the relative cooling power of DyCo2B0.05 is increased about 18%.

The magnetic properties and magnetic entropy changes of DyCo2Bx (x=0, 0.05, 0.1, and 0.2) alloys were investigated. The Curie temperature (TC) increases with increasing B concentration. The frequency dependence of ac magnetic susceptibility of DyCo2 caused by the narrow domain wall pinning effect is depressed by B doping, but the coercivity and the magnetic viscosity are prominently increased in the B doped alloys. The magnetic transition nature of DyCo2Bx changes from the first-order to the second-order with increasing x, which leads to the decrease of the maximum magnetic entropy change. However, the relative cooling power (RCP) of DyCo2 and the B doped alloys remains nearly constant.