A microelectronic device comprises a stack structure comprising insulative levels vertically interleaved with conductive levels. The conductive levels individually comprise a first conductive structure, and a second conductive structure laterally neighboring the first conductive structure, the second conductive structure exhibiting a concentration of β-phase tungsten varying with a vertical distance from a vertically neighboring insulative level. The microelectronic device further comprises slot structures vertically extending through the stack structure and dividing the stack structure into block structures, and strings of memory cells vertically extending through the stack structure, the first conductive structures between laterally neighboring strings of memory cells, the second conductive structures between the slot structures and strings of memory cells nearest the slot structures. Related memory devices, electronic systems, and methods are also described.