Glass formation and confined melting in sol-gel derived nano ZnO aggregates

S. Toscani (1) , Olivier Hernandez (1) , Claudia Aparicio , Lubomir Spanhel (2)

1 ISCR - Institut des Sciences Chimiques de Rennes
2 Laboratoire Verres et Céramiques

Sol–gel processing of ZnO nanocolloids has been revisited to prepare various alkaline metal acetate (MAc: K, Na, Li-acetates) containing ZnO nanopowders. Using differential scanning calorimetry and X-ray diffraction investigations, several new relationships between the morphology and the thermodynamic behavior in the aforementioned particulate ZnO/MAc nanocomposites were noticed: (1) large MAc melting depression shifts −ΔTm ~ 80 °C due to salt confinement within porous ZnO aggregates, (2) corresponding MAc crystallization and re-crystallization temperature depression shifts, (3) presence of multimodal pore size distributions within nanoaggregates and (4) glass formation at temperatures Tg between −40 and 130 °C. We also note that the Tg value drops with rising alkaline metal size, increasing water content and decreasing ZnO particle size. In contrast, Tg rises in the case of co-doped Fe–LiAc/ZnO compositions.

Mots clés: Nanoparticles Melting confinement ZnO Sol–gel glasses

Domaines: Matériaux

S. Toscani, Olivier Hernandez, Claudia Aparicio, Lubomir Spanhel. Glass formation and confined melting in sol-gel derived nano ZnO aggregates. Journal of Sol-Gel Science and Technology, 2014, 69 (2), pp.457-463. ⟨10.1007/s10971-013-3184-5⟩. ⟨hal-01096986⟩