Evolution towards charge density instability in Ba-Sb-Te-S stoichiomorphs

We present a stoichiometrically conserved framework, BaSbQ₃ (Q = Te1-xSx), where each value of x gives rise to a distinct phase, differing only in the size and assembly of fundamental building blocks of A₁ (BaSbSTe₂) and B_n (Ba_nSb_nS_n-1Te_2n+1) (Zhao et al. Science, 2025, in press) (1). We show how infinite structural diversity can be designed by leveraging differences in anion electron affinity and sizes. The structural evolution drives increasing electronic instabilities hosted by the polytelluride hierarchical networks, eventually leading to the precipitation of an incommensurate charge density order with q = 0.351(1)b^* in BaSbTe₂S (2). The CDW can be suppressed by pressure, leading to the emergence of superconductivity with a T_c up to 7.5 K at 13.6 GPa, suggesting a competition between the CDW order and superconductivity. This work demonstrates a generic design concept we termed as “anionic disparity” for the design and predictive synthesis of novel quantum materials at the molecular level in extended solids.