Variation in lattice parameters with grain size of a nanophase Ni3P compound

Nanocrystalline Ni-P alloy samples consisting of the compound Ni3P and Ni solution with different grain sizes were synthesized by crystallization of the amorphous alloy. The lattice parameters of the Ni3P nanophases with grain sizes ranging from 80 to 6.0 nm were measured by X-ray diffraction. It was found that for the nanometer-sized Ni3P phase, the lattice parameter a is always larger and c is smaller than the equilibrium values a 0 and c 0 of the perfect crystal attice respectively. With a reduction in the grain size, the value of a increases and c decreases, resulting in more significant lattice distortion. The origin of such lattice distortion was analyzed according to the thermodynamic state of th6 nanometer-sized crystallites. 1