A structural investigation of Ag 0.167TiS 2 by time-of-flight neutron powder diffraction

The structure of Ag _0.167TiS ₂ has been determined at several temperatures from time-of-flight neutron powder diffraction data. At 305 K, Ag _0.167TiS ₂ is a stage-II complex which belongs to the space group P3¯m1, with a = 3.4161(4)Åand c = 12.100(2)Å. When the temperature is lowered to 13 K, the lattice parameters decrease, but no phase change or superlattice formation is observed. Upon heating to 1123 K, this compound transforms to a stage-I structure belonging to the space group P3¯m1, with a = 3.4676(1)Åand c = 6.2247(4)Å. No further phase changes are observed when the temperature is raised to 1323 K. When this compound is slowly cooled to ambient temperature from 1323 K, it transforms quantitatively to the original stage-II structure. The Rietveld refinements of Ag _0.167TiS ₂ at six temperatures are presented and discussed.