31Psolid-state NMR studies of the short-range order in phosphorus–selenium glasses

Abstract

The local structure of P-rich and Se-rich phosphorus–selenium glasses was studied using high-resolution ³¹P solid-state MAS NMR. Two-dimensional ³¹P homonuclear through-bond correlation MAS experiments and 2D homonuclear J-resolved MAS measurements were performed at high spinning frequency to probe P–P and P–Se–P connectivities between the different P sites for the compounds in two glass-forming regions, P_2.5Se_97.5–P₅₀Se₅₀ and P₆₇Se₃₃–P₈₄Se₁₆. Amorphous phosphorus and crystalline α-P₄Se₃ and β-P₄Se₃ were also studied as reference materials. Glasses from the Se-rich region contain mainly three- and four-coordinated P sites linked together by Se_n chains, whereas P-rich glasses contain a mixture of P₄Se₃ molecular units and possibly other structural units embedded in a red-phosphorus-like polymeric network.