STRUCTURE AND LATTICE-PARAMETERS OF COCL2 NEAR THE MAGNETIC PHASE-TRANSITION

Using the powder x-ray diffractometry method, we have obtained for the first time data on the lattice parameters of CoCl2 in the temperature range from 5 to 293 K. The room-temperature lattice parameters are in good agreement with the previously known values of other researchers. With the aid of the data obtained we estimate tile spontaneous magnet ostriction in tile ordered phase of this chloride. The estimated latti ce distortions at the phase transition coincide in sign with those in NiCl2 but are opposite to those in FeCl2.