MAGNETIC-PROPERTIES OF TB2MN17CX COMPOUNDS STUDIED BY MAGNETIC MEASUREMENTS AND NEUTRON-DIFFRACTION

Compounds of the type Tb2Mn17Cx with x = 0.9, 1.8 and 2.7 were prepare d by arc melting. The crystal structure of these compounds was studied by means of neutron diffraction. All these compounds were found to ha ve crystallised in the hexagonal Th2Ni17-type structure. The refinemen t results of the neutron-powder-diffraction patterns show that the C a toms occupy exclusively the 6h site. Magnetic measurements made on the se compounds show that they do not give rise to a well defined magneti c ordering transition at low temperatures. This is interpreted in term s of three different mechanisms that randomise the exchange interactio ns in these compounds and lead to spin-glass or cluster-glass behaviou r.