Fabrication of nanocrystalline and amorphous Chevrel phase PbMo_6S_8 powder by ball milling

摘要

Chevrel phase PbMo_6S_8 (PMS) superconducting powder ball-milled from 5 to 200 h has been investigated using X-ray diffraction (XRD) and scanning and transmission electron microscopy. Ball milling produced particles with crystallites of PMS in the range 10-100 nm and amorphous phase. From XRD data, it was found that the crystallite size decreased and lattice strain increased with increasing milling time until by 200 h the material was predominantly amorphous. The powder ball-milled for 100 h was subsequently annealed at temperatures from 400 to 1000℃ for 8 h. Annealing at 600℃ and above released the lattice strain. At 800℃ and above the amorphous phase crystallised and grains coarsened with sizes in the range 50-100 nm.