Figure 2. Thermal stability of 1D sulphur chains with zigzag and linear geometries.

Temperature dependence of the 1D Bragg peaks of sulphur inside (a) SWCNTs and (b) DWCNTs. Temperature dependence of the axial lattice constant d in (c) 1D zigzag and (d) linear sulphur chains. The melting point (m.p.) and boiling point (b.p.) of bulk sulphur (α-S₈) are shown for comparison. A sharp increase in the d value of S@DWCNT between 450–650 K indicates a structural change of the 1D chains.