Structure analysis of NiZr2 in reciprocal and real space

The temperature dependence of the geometric structure of amorphous and crystallized Ni(33)Zr(67) was investigated by means of in situ synchrotron X-ray diffraction. The crystal structure parameters of the tetragonal NiZr(2) phase were determined by the Rietveld refinement of the X-ray diffraction patterns. The lattice parameters alpha(0), c(0), and therefore the inter-atomic distances increase linearly with temperature. The behavior of the short-range order was analyzed by the corresponding atomic pair correlation functions G(r). The position of the first maximum of G(r) at r(1) decreases with temperature. The analysis of real space data of the crystallized state of Ni(33)Zr(67) shows that the measured G(r) function consists of several superimposed, non-resolved inter-atomic distances. The individual distances increase with temperature in agreement with the Rietveld analysis. The position of the first maximum r, is additionally influenced by the thermal broadening of the distance distributions leading to the "unphysical" reduction of r(1) with temperature.