Intermediate valence behavior of the ternary cerium-nickel-phosphide Ce2Ni12P5

Abstract

The crystal structure of the ternary phosphide Ce₂Ni₁₂P₅ (La₂Ni₁₂P₅-type structure) has been determined from X-ray powder diffraction data: full profile refinement, monoclinic symmetry, space group P2₁/m, a = 10.7809(2) Å, b = 3.6869(1) Å, c = 13.1490(3) Å, β = 107.776(4)º, R_I = 0.068, R_P = 0.044, R_wP = 0.060. Ce₂Ni₁₂P₅ is a ferromagnet with a Curie temperature of 5.8(5) K. A significant deviation from the linearity of the temperature dependence of the electrical resistance for Ce₂Ni₁₂P₅ has been found. The low-temperature part of the electrical resistance indicates the presence of magnetic interactions in Ce₂Ni₁₂P₅. The influence of a magnetic field on the electrical resistance of Ce₂Ni₁₂P₅ has been studied. The X-ray absorption spectrum at the Ce L_III edge and X-ray emission spectra of Ni and P at the K and L_III edges have been studied experimentally and theoretically using DFT+U calculations. The calculations show good agreement with the experimental measurements. The effective valence of Ce in Ce₂Ni₁₂P₅ determined based on the Ce L_III absorption spectrum is ϑ_eff ∼ 3.05.