Truncated Lorch-window method revealing the off-octahedral Ge in nanocrystalline Ge₂Sb₂Te₅

Traditional Lorch-window technique was modified to the truncated Lorch-window through various truncation ranges to apply the Lorch-window functions. The terminal ripples in radial distribution functions (RDFs) were weakened and the shoulder peak at 2.6Å in crystalline Ge₂Sb₂Te₅ (GST) was revealed by the indication of the off-octahedral Ge. The Cs-corrected high resolution transmission electron microscopy image and the corresponding simulations suggest that the off-octahedral Ge atoms are indeed in the tetrahedral symmetry. These results indicate that the complex structural details in the intermediate phase of GST other than simple rock-salt structure though the quantified information, such as the accurate atomic positions of the off-octahedral Ge need being further clarified in the future. These results also reveal the significance of high-Q signals in revealing the structures in short range order.