PROPERTIES OF THE LAYERED BACO1-XNIXS2 ALLOY SYSTEM

Compounds of the layered transition metal sulfide alloy series BaCo1-x NixS2 were prepared. Structural, magnetic, and electrical properties w ere measured. These compounds consist of quasi-two-dimensional transit ion metal sulfur sheets separated by BaS rocksalt layers. With increas ing Ni the BaCo1-xNixS2 alloys change continuously from antiferromagne tic semiconductors to paramagnetic metals. The crossover in the electr ical and magnetic properties both occur near x=0.25. The initial suppr ession of the Neel temperature with Ni substitution is characteristic of simple magnetic dilution in a quasi-two-dimensional Heisenberg anti ferromagnet. The measured electrical and magnetic properties of the Ni -rich alloys are consistent with the calculated one-electron band stru cture of BaNiS2. The Go-rich alloys appear to be Mott-Hubbard insulato rs with electrical and magnetic properties very similar to those of La 2CuO4, the parent compound of the cuprate superconductors.