Ultrafast crystallization kinetics of “bad metal” nanocomposite CuZr–Sb phase-change materials

The development of high-performance, tellurium-free phase-change materials (PCMs) with simultaneous ultrafast crystallization and good thermal stability remains a key challenge for next-generation non-volatile memory technologies. Here, we report a novel design strategy based on a “bad metal” nanocomposite architecture, realized by incorporating a thermally stable CuZr intermetallic compound into an antimony (Sb) matrix. The resulting CuZr-Sb system exhibits a unique combination of properties: the strong Cu-Zr bonding prevents chemical interaction with Sb, enabling the CuZr phase to remain chemically inert and amorphous during phase transitions, thereby providing physical confinement within the Sb matrix. This nanocomposite structure is confirmed by XPS and HRTEM analyses. Among various compositions, (CuZr) 9 Sb 91 demonstrates optimal performance, with a high crystallization temperature ( T c = 170 °C), the good thermal stability ( T 10-years = 78.7 °C), a large activation energy ( E a = 2.88 eV), and a high on/off resistance ratio of ∼10 3 . Fast differential scanning calorimetry reveals ultrafast crystallization kinetics, with a maximum growth velocity ( U max ) of 17 m s -1 , among the highest reported for Sb-based systems. The T c evolution with composition follows a distinct “Z”-shaped trend, correlating with lattice parameter changes in the rhombohedral Sb phase. These results demonstrate that rational phase-segregation engineering in Sb-based matrices enables the concurrent achievement of speed and stability, offering a promising pathway beyond conventional chalcogenide PCMs.