Crystal structure and magnetic properties of LaCo10Al3

Abstract

The crystal structure and magnetic properties of a LaCo₁₀Al₃ intermetallic compound have been investigated by x‐ray powder diffraction and magnetic measurement. The space group of the LaCo₁₀Al₃ structure is I4/mcm, which can be derived from the cubic NaZn₁₃‐type structure. Each unit cell contains four formula units of LaCo₁₀Al₃. The lattice parameters are a=8.085(1) Å, c=11.624(8) Å, and the calculated density is D_x=7.07(3) g/cm³. In each unit cell, there are five kinds of equivalent positions, i.e., 4a, 16l(1), 16k 16l(2), and 4d, which are occupied by 4La, 16Co⁽¹⁾, 16Co⁽²⁾, 16(Co+Al) and 4Co⁽³⁾ atoms, respectively. The tetragonal LaCo₁₀Al₃ intermetallic compound is ferromagnetic with a Curie temperature of 840 K. The magnetic moment per Co atom is 0.84μ_B, which can be explained by the magnetic valence model.