Tailorable fragile-to-strong kinetics features of metal oxides nanocomposite phase-change antimony films

A fragile-to-strong (F-S) kinetics feature is desirable in phase-change supercooled liquids, for decoupling the contradictory relation between good thermal stability nearby glass transition temperature and fast crystallization speed around melting temperature. We designed three metal oxides (MOs), i.e., the fragile TiO ₂, the moderate ZnO, and the strong GeO ₂ , doping into a very fragile Sb matrix, which is an ideal elementary phase-change material (PCM) for overcoming the composition segregation in fatigued device, to tailor the F-S transition behavior in their supercooled liquids. Depending on the crystallization kinetics analyses of three representative films, which all exhibit the similar thermal stability with crystallization temperature of 200 ± 6 ºC, crystallization activation energy of 2.83 ± 0.09 eV, and the temperature for ten years data retention of 101 ± 7 ºC, we found no F-S behavior in the Sb _62.1(TiO ₂) _37.9 film, but weak and strong F-S behavior in Sb _82.7(ZnO) _17.3 and Sb _73.6(GeO ₂) _26.4 film, respectively. It shows that, the Sb based nanocomposite films with different MOs that have various fragilities can bring tailorable F-S kinetics features. Nevertheless, although the metal elementaries of Ti, Zn, Ge, have been confirmed could not bond with the Sb atoms, the Sb ₂O ₃ phase are detected more or less in Sb _62.1(TiO ₂) _37.9 and Sb _82.7(ZnO) _17.3 but not found in Sb _73.6(GeO ₂) _26.4 film. It is thus believed the formation of Sb ₂O ₃ would impede the F-S behavior in the supercooled liquids. The Sb _73.6(GeO ₂) _26.4 film that has large F-S transition magnitude of 2.3 and high F-S transition temperature of 536 K, is suggested to be a candidate for potential phase-change memory application. Such distinct F-S behavior in nano-size confined Sb _73.6(GeO ₂) _26.4 matrix, which consists of phase-changeable Sb and non-phase-changeable GeO ₂, stems from the competition between short-range ordering cluster that with abundant Peierls-like distortions in fragile Sb phase and medium-range ordering cluster that with energetical favorable networks in strong GeO ₂ phase.