X-RAY AND NEUTRON-DIFFRACTION STUDY OF THE CRYSTAL-STRUCTURE OF MNS2

X-ray (293 K) and neutron diffraction (15 K, 67 K, 120 K, 293 K) intensities have been measured from natural single crystals of MnS2. The lattice parameter, interatomic distances and thermal parameters of Mn and S atoms vary approximately linearly in the temperature range from 15 K to 540 K. The mean volume thermal expansion coefficient is found to be betaBAR = 3.70 x 10(-5) K-1. The vibrational amplitudes of the Mn and S atoms are practically the same at 15 K but at 293 K the vibrational amplitude of the Mn atom becomes 25% larger than that of sulfur. The interatomic distances of MnS2 have been compared with those of other pyrite-structure transition metal dichalcogenides and the nature of chemical bonding in these compounds has been discussed.