Antagonistic Pairs: a pathway to the discovery of new quasi-low dimensional materials

A foundational goal of materials chemistry is to develop general design principles for synthesizing materials with targeted structural motifs and physical properties. We propose that pairs of strongly immiscible elements, referred to here as antagonistic pairs,¹ can be used to produce ternary compounds with low or quasi-reduced dimensionality intrinsically built into their crystal structures. Many pairs of elements offer essentially no miscibility, of which examples are Co-Pb, Cr-La, and Fe-Ag. The heart of our work is to leverage third elements that are mutually compatible with any given immiscible pair to form stable ternary compounds containing that pair. When such ternary compounds can be made, we discuss how the immiscibility of the antagonistic pair is remarkably preserved in the ternary crystal structures, with the third element separating the immiscible atoms into spatially separated substructures. Quasi-low dimensional structural units, such as chains or sheets, are the consequence of the immiscible atoms seeking to avoid close contact in the solid-state. Finally, we present the growth and characterization of single crystals of several new, 3d transition metal containing, ternary compounds based on antagonistic pairs and which feature quasi-2D structural motifs, concluding with an overview of their magnetic and transport properties.



[1] P. C. Canfield, Reports on Progress in Physics 83, 016501, 2019