Synthesis\nand Stability Phase Diagram of Topological\nSemimetal Family LnSb<sub><i>x</i></sub>Te<sub>2–<i>x</i>–δ</sub>

The solid solution LnSb<sub><i>x</i></sub>Te<sub>2–<i>x</i>–δ</sub> (Ln = lanthanide)\nis a family of\nsquare-net topological semimetals that exhibit tunable charge density\nwave (CDW) distortions and band filling dependent on <i>x</i>, offering broad opportunities to examine the interplay of topological\nelectronic states, CDW, and magnetism. While several Ln series have\nbeen characterized, gaps in the literature remain, inviting a systematic\nsurvey of the remaining composition space that is synthetically accessible.\nWe present our efforts to synthesize LnSb<sub><i>x</i></sub>Te<sub>2–<i>x</i>–δ</sub> across the\nremaining lanthanides via chemical vapor transport. Compiling our\nresults with the reported literature, we generate a stability phase\ndiagram across the ranges of Ln and <i>x</i>. We find a\nstability boundary for intermediate <i>x</i> beyond Tb,\nwhile <i>x</i> = 1 and <i>x</i> = 0 can be isolated\nup to Ho and Dy, respectively. SEM and XRD analyses of unsuccessful\nreactions indicated the formation of several stable binary phases.\nThe presence of structurally related LnTe<sub>3</sub> in samples suggests\nthat stability is limited by the size of Ln, due to increasing compressive\nstrain along the layer stacking axis with decreasing size. Finally,\nwe demonstrate that late Ln can be stabilized in LnSb<sub><i>x</i></sub>Te<sub>2–<i>x</i>–δ</sub> via substitution into larger Ln members, synthesizing La<sub>1–<i>y</i></sub>Ho<sub><i>y</i></sub>Sb<sub><i>x</i></sub>Te<sub>2–<i>x</i>–δ</sub> as\na proof of concept.