Thermal Expansion Anomaly and Spontaneous Magnetostriction of Y₂Fe₁₄Al₃ Compound

The structure and magnetic properties of Y₂Fe₁₄Al₃ compound are investigated by means of x-ray diffraction and magnetization measurements. The Y₂Fe₁₄Al₃ compound has a hexagonal Th₂Ni₁₇-type structure. Negative thermal expansion is found in Y₂Fe₁₄Al₃ compound in the temperature range from 403 to 491K by x-ray dilatometry. The coefficient of the average thermal expansion is ^-α=-2.54 ×10^-5K^-1. The spontaneous magnetostrictive deformations from 283 to 470K are calculated by means of the differences between the experimental values of the lattice parameters and the corresponding values extrapolated from the paramagnetic range. The result shows that the spontaneous volume magnetostrictive deformation ω_S decreases from 5.74×10^-3 to nearly zero with temperature increasing from 283 to 470K, the spontaneous linear magnetostrictive deformation λ_c along the c-axis is larger than the spontaneous linear magnetostrictive deformation λ_a in basal-plane in the same temperature below 350K.