Abstract
In the present paper, the influence of partial substitution of Mn by Pd on structure, thermomagnetic properties, and phase transitions in the MnCoGe alloys was investigated. The studies of phase constitution revealed an occurrence of the orthorhombic TiNiSi-type and hexagonal Ni(2)Ti- type phases. Deep analysis of the XRD pattern supported by the Rietveld analysis allowed us to notice the changes in lattice parameters and quantity of recognized phases depending on the Pd content. An increase of palladium in alloy composition at the expense of manganese induced a rise in the Curie temperature. The values of ΔS(M) measured for the variation of external magnetic field ~5 T equaled 8.88, 23.99, 15.63, and 11.09 for Mn(0.97)Pd(0.03)CoGe, Mn(0.95)Pd(0.05)CoGe, Mn(0.93)Pd(0.07)CoGe, and Mn(0.9)Pd(0.1)CoGe alloy, respectively. The highest magnetic entropy change ΔS(M) was observed for samples with Pd content x = 0.05 induced by magnetostructural transformation. The analysis of the n vs. T curves allowed confirmation of the XRD and DSC results of an occurrence of the first-order magnetostructural transition in Mn(0.95)Pd(0.05)CoGe and Mn(0.93)Pd(0.07)CoGe alloys samples.