MAGNETIC-PROPERTIES OF STAGE-2 RANDOM-MIXTURE GRAPHITE-INTERCALATION COMPOUNDS AND THEIR BULK INTERCALANTS

The magnetic properties of stage-2 Co(c)M(1-c)Cl(2) graphite intercala tion compounds (GICs) (M=Ni and Mn, 0 less than or equal to c less tha n or equal to 1) and their bulk intercalants, Co(c)M(1-c)Cl(2), have b een studied by using d.c, magnetic susceptibility. In stage-2 Co(c)M(1 -c)Cl(2) GIC, the adjacent Co(c)M(1-c)Cl(2) layers are separated by tw o graphite layers. Due to the graphite host effect, demonstrated by de creasing the antiferromagnetic interplanar exchange interaction and is land formation in the intercalate layer, the magnetic phase transition of stage-2 Co(c)M(1-c)Cl(2) GIC is very different from that of Co(c)M (1-c)Cl(2). Stage-2 CocNi1-cCl2 GIC with 0 less than or equal to c les s than or equal to 1 and stage-2 CocMn1-cCl2 GIC with 0.45 less than o r equal to c less than or equal to 1 undergo a two-dimensional ferroma gnetic phase transition at the critical temperature T-c. while their b ulk intercalants undergo a three-dimensional antiferromagnetic phase t ransition at the Neel temperature T-N The magnetic properties of stage -2 GICs are compared with those of their respective bulk intercalants in the light of the graphite host effect. The magnetic properties of s tage-2 CocMn1-cCl2 GIC and CocMn1-cCl2 are also compared with those of stage-2 CocMg1-cCl2 GIC and CocMg1-cCl2.