| The entropy-modulated material has been a hot topic due to its special design concept and excellent properties.In this study,the concept of configuration entropy modulation is introduced into the dilute magnetic alloys,and the structural formula of RESn3xCox(RE=rare earth;x=0,3)matrix is replaced by equal atomic ratio,according to designs of the chemical formula RESn3,RE(Sn1/2In1/2)3,(RE1,RE2,RE3)(Sn1/2In1/2)3,RE(Fe1/3Co1/3Ni1/3)3,(RE1,...,REn)(Fe1/3Co1/3Ni1/3)3,(RE=La,Ce,Pr,Nd,Sm,Gd,Tb,Dy,Ho),and series of entropized samples are prepared.It is expected to stabilize single-phase structure and improve magnetic properties,the structure and magnetic properties are studied.The sample was prepared by vacuum arc furnace melting,and the powder samples were identified by X-ray diffractometer(XRD).The TREOR program was used to index the powder sample.The Rietveld structural refinement technique was used to further determine the crystal structure,the phase formation rule is discussed.Structural analysis shows that the phase formation of RESn3-xCox series alloys is related to the atomic size factors and electronegativity factors.The two phases are observed for the samples of RESn3,which are prepared at room temperature and one atmosphere,however,the design of entropy configuration with equimolar ratio at Sn site and RE site can stabilize the cubic phase with AuCu3 structural type.The impurity of β-Sn phase is melted in the alloys.The rare earth elements occupy the 1a(0,0,l)crystal site,and the Sn and In elements occupy the 3c(1/2,1/2.0)crystal site.All elements are randomly dissolved at the design crystal site.For the entropized RECo3 intermetallics:RE(Fe1/3Co1/3Ni1/3)3 and(RE1,...,REn)(Fe1/3Ci1/3Ni1/3)3,are PuNi3 single phase with five non-equivalent crystal sites,where the rare earth elements occupy 3a(0,0,0)and 6c(0,0,z)crystal sites.The transition metals Co,Fe and Ni occupy the 3b(0,0,1/2),6c(0,0,z)and 18h(1/2,1/2,z)crystal sites,and the elements are randomly dissolved at the design crystal sites.The magnetic analysis shows that the magnetic anisotropy at room temperature can be changed from the direction of the easy axis to the easy plane by the high entropy of the metal site.The entropized samples exhibit mixed magnetism and low temperature ferromagnetism at room temperature.The entropized samples of light rare-earth base show a significantly higher magnetic moment than the matrix,while the samples of heavy rareearth base show no significant improvement.Coercivity is very small for all block samples at room temperature.It shows soft magnetic properties.However the coercivity is observed at low temperature and it shows hard magnetic properties.The variation of coercivity is closely related to the elements introduced by entropy modulated.The grain refinement of powder samples is helpful to improve coercivity.The entropy modulated design achieves the improvement of the magnetic properties of the matrix,the essence of the influenced by entropy modulated design on saturated magnetic moment is that the multi-principal element disorder design introduced by high entropy has an effect on the number of free s electrons,which can modulated the 4f-3d indirect exchange by s electrons as the medium.The anti-parallel electron spin pairs of RE-T ↑ also affect the saturated magnetic moment. |
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