Kinetic and Thermodynamic Pathways Via Ion Exchange Metathesis of Cobalt Thiophosphate

Abstract

Transition metal chalcogenophosphates have garnered extensive attention owing to their diverse array of optical and magnetic properties. However, one of the less explored members within this family is CoPS 3 , largely due to the time-intensive nature of its solid-state synthesis preparation. In this study, we present an ion exchange metathesis methodology to address these challenges. Through the exploitation of the versatile thiophosphate motif, we have successfully synthesized CoPS 3 by reacting isostructural MgPS 3 with CoCl 2 . Our findings from ex situ investigations highlight a correlation between the degree of structural disorder and the concentration of CoCl 2 , impacting not only the bulk magnetism but also the observed phonon modes, as evidenced by magnetic susceptibility and Raman spectroscopy, respectively. This structural disorder seemingly plays a pivotal role in shaping the mechanism underlying the formation of CoPS 3 through the metathesis approach, which we comprehensively elucidate using in situ synchrotron powder X-ray diffraction. Our detailed analysis uncovers a two-step progression in the metathesis reaction involving ion diffusion kinetics and grain boundary melt phenomena. These insights not only enhance our understanding of the reaction dynamics but also pave the way for refining and optimizing the synthesis of such compounds with the desired structures and properties.