| dc.description |
Physical measurements have been made on samples of α- and β-RuCl3 of relatively high purity. From X-ray powder patterns, the existence of a superstructure has been detected in α-RuCl3, and the structure of β-RuCl3 has been found to be of the β-TiCl3 type with linear chains of ruthenium atoms lying in distorted octahedra of chlorine atoms. The infrared spectra have been obtained down to 70 cm.<sup>â 1</sup>; the nine bands observed for β-RuCl3 indicate that the space group is the trigonal P3c1 (C <sup>3</sup> 3v ), which means that there areâ RuCl3â RuCl3â RuCl3â units in the chains. There is a strong band attributed to a Ruâ Cl stretching vibration at the relatively high frequency of 376 cm.<sup>â 1</sup>. The magnetic susceptibilities, obtained from 8 to 740°K for α-RuCl3, and from 8 to 560°K for β-RuCl3, show that α-RuCl3 is antiferromagnetic below 13°K, and β-RuCl3 below ca. 600°K, but in neither case has the antiferromagnetism been detected by neutron diffraction. The temperature dependence of the susceptibilities has been compared with the predictions of crystal field theory for α-RuCl3, and with the theory of linear Heisenberg chains for β-RuCl3. |
