Functional Indium Vacancies in Indium Phosphors Chalcogenides

ABSTRACT Layered Indium phosphorus trichalcogenides (In 4/3 P 2 X 6 ) have received significant attention due to their ordered indium vacancies and stacking‐dependent properties, enabling applications in electronics, catalysis, and energy storage. However, the vacancy‐governed stacking polytypes and atomic structures in In 4/3 P 2 X 6 remain elusive. Moreover, the facile reconstruction of the indium vacancies upon external stimulus makes their direct visualization challenging. Here, a low‐dose aberration‐corrected scanning transmission electron microscopy (STEM), four‐dimensional STEM (4D‐STEM) techniques, and density functional theory (DFT) are employed to systematically explore the atomic structure of In 4/3 P 2 X 6 and the magnetic properties of doped In 4/3 P 2 X 6 . The indium vacancies with glide‐reflection symmetric ordering in In 4/3 P 2 X 6 are resolved at the atomic scale, driving armchair‐type interlayer gliding with an unconventional step in In 4/3 P 2 Se 6 and zigzag‐type gliding in In 4/3 P 2 S 6 , yielding ABC and nearly‐ABC stacking polytypes, respectively. DFT calculations reveal that both gliding modes are energetically favorable, with their distinctions arising from the ligand‐modulated interlayer charge distributions. Besides, filling the indium vacancies with magnetic dopants induces tunable magnetic ordering in In 4/3 P 2 X 6 , and also drives a structural transition to an MPX 3 ‐like phase and a non‐magnetic paramagnetic (PM)−FM transition. This study sheds light on vacancy‐governed structure in In 4/3 P 2 X 6 and highlights it as an excellent matrix for designing novel functional 2D magnets via doping engineering.