The influence of partial substitution of La by Dy on structure and thermomagnetic properties of the LaFe11.0Co0.7Si1.3 alloy

Highlights: • The structure and magnetocaloric effect of the La_1−xDy_xFe_11.0Co_0.7Si_1.3 alloys (where x = 0, 0.1, 0.2) have been studied first time. • The gradual decrease of magnetic entropy change with an increase of Dy content was observed. • The values of exponent n (ΔS_M = C·(B_max)ⁿ), calculated in the vicinity of the Curie point of investigated specimens, are similar to theoretical values. The aim of the following paper was to study the structure and magnetocaloric effect of the La_1−xDy_xFe_11.0Co_0.7Si_1.3 alloys (where x = 0, 0.1, 0.2). The X-ray diffraction showed a coexistence of two phases: the dominant La(Fe,Si)₁₃ and minor α-Fe. The Rietveld analysis revealed a gradual decrease in the lattice constant of the La(Fe,Si)₁₃ structure with increase in Dy addition. Moreover, the Curie temperature reached 267, 265.5 and 269 K for x = 0, 0.1 and 0.2, respectively. The values of magnetic entropy change equaled 14.6, 11.2 and 9.2 J(kg K)⁻¹ for the LaFe_11.0Co_0.7Si_1.3, La_0.9Dy_0.1Fe_11.0Co_0.7Si_1.3 and La_0.8Dy_0.2Fe_11.0Co_0.7Si_1.3 alloys, respectively. The values of exponent n (according to ΔS_M = C·(B_MAX)ⁿ) calculated at the Curie temperature were 0.67 for base sample and 0.70 for specimens modified by Dy. The determined values correspond well with theoretical predictions.