Investigation on the 773 K isothermal section of Ho-Ni-Si ternary phase diagram by X-ray powder diffraction and magnetic property of Ho3NiSi2 alloy

Abstract

The isothermal section of the Ho-Ni-Si system at 773 K was constructed by X-ray powder diffraction (XRD) in this work. The system contains sixteen known type structure compounds TiNiSi-type HoNiSi, BaAl4-type HoNi2Si2, CeNiSi2-type HoNiSi2, U2Co3Si5-type Ho2Ni3Si5, SmNiGe3-type HoNiSi3, Ce3Ni6Si2-type Ho3Ni6Si2, ThMn12-type HoNi10Si2, YPd2Si-type HoNi2Si, YNi5Si3-type HoNi5Si3, YNi4Si-type HoNi4Si, Gd3NiSi2-type Ho3NiSi2, YNi6Si6-type HoNi6Si6, AlB2-type Ho2NiSi3, AlB2-type Ho3Ni2Si4, AlB2-type Ho4NiSi7, Gd3Ru4Al12-type Ho8Ni31Si11, and one unknown type structure compound Ho5Ni2Si3. At the same time, one unknown structure new phase Ho37Ni3Si60 was observed. In ternary compounds, Ho2NiSi3 and Ho4NiSi7 have the solid solution phenomena; the solid solution ranges are about Ho33.3Ni18.7-9.7Si∼48.0-57.0 and Ho33.Ni∼8.3-2.6Si∼58.3-64.1, respectively. At the same time, quasi-binary solid solutions were detected at 773 K for Ho2Ni17, HoNi5, Ho2Ni7, HoNi3, HoNi2, HoNi, HoSi. Other binary compounds of the Ho-Ni-Si system do not show any visible solubility. The magnetic property studies show that Ho3NiSi2 compound has two successive magnetic phase transitions in a low field: a spin-reorientation transition at TSR = 10 K and a second order ferromagnetic (FM) - paramagnetic (PM) transition at Tc = 37 K.