Long period superstructures related to partial ordering in Ni_3±xTe₂ as studied by means of electron diffraction

Different structures of the intermetallic compound Ni^3±xTe² are known. An electron microscopy study reveals the existence of a quasi‐continuous series of superstructures between the monoclinic low temperature phase and a new orthorhombic phase. A possible interpretation of this series is based on the concept of partially ordered intermediate phases. The most significant characteristic of these phases is the presence along the [h00]* row of a pair of irrational superlattice reflections shifting continuously in position as a function of the degree of order. The proposed model is based in agreement with the relative intensities of the superlattice reflections.