Phase transformations at the nanoscale represent a challenging field of research, mainly in the case of nanocrystals (NCs) in a solid host, with size-effects and interactions with the matrix. Here we report the study of the structural evolution of γ-Ga2O3 NCs in alkali-germanosilicate glass-a technologically relevant system for its light emission and UV-to-visible conversion-showing an evolution drastically different from the expected transformation of γ-Ga2O3 into β-Ga2O3. Differential scanning calorimetry registers an irreversible endothermic process at ∼1300 K, well above the exothermic peak of γ-Ga2O3 nano-crystallization (∼960 K) and below the melting temperature (∼1620 K). Transmission electron microscopy and X-ray diffraction data clarify that glass-embedded γ-Ga2O3 NCs transform into LiGa5O8 via diffusion-driven kinetics of Li incorporation into NCs. At the endothermic peak, β-Ga2O3 forms from LiGa5O8 dissociation, following a nucleation-limited kinetics promoted by size-dependent order-disorder change between LiGa5O8 polymorphs. As a result of the changes, modifications of UV-excited NC light emission are registered, with potential interest for applications.

Golubev, N., Ignat'Eva, E., Sigaev, V., Lauria, A., De Trizio, L., Azarbod, A., et al. (2015). Diffusion-driven and size-dependent phase changes of gallium oxide nanocrystals in a glassy host. PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 17(7), 5141-5150 [10.1039/c4cp05485g].

Diffusion-driven and size-dependent phase changes of gallium oxide nanocrystals in a glassy host

Azarbod, A;Paleari, A
;
Lorenzi, R
2015

Abstract

Phase transformations at the nanoscale represent a challenging field of research, mainly in the case of nanocrystals (NCs) in a solid host, with size-effects and interactions with the matrix. Here we report the study of the structural evolution of γ-Ga2O3 NCs in alkali-germanosilicate glass-a technologically relevant system for its light emission and UV-to-visible conversion-showing an evolution drastically different from the expected transformation of γ-Ga2O3 into β-Ga2O3. Differential scanning calorimetry registers an irreversible endothermic process at ∼1300 K, well above the exothermic peak of γ-Ga2O3 nano-crystallization (∼960 K) and below the melting temperature (∼1620 K). Transmission electron microscopy and X-ray diffraction data clarify that glass-embedded γ-Ga2O3 NCs transform into LiGa5O8 via diffusion-driven kinetics of Li incorporation into NCs. At the endothermic peak, β-Ga2O3 forms from LiGa5O8 dissociation, following a nucleation-limited kinetics promoted by size-dependent order-disorder change between LiGa5O8 polymorphs. As a result of the changes, modifications of UV-excited NC light emission are registered, with potential interest for applications.
Articolo in rivista - Articolo scientifico
Nanostructured glassceramic, gamma-Ga2O3, solgel synthesis, nanoparticle, XRD, photoluminescence, DSC, crystal growth, coalescence, LiGa5O8
English
2015
17
7
5141
5150
partially_open
Golubev, N., Ignat'Eva, E., Sigaev, V., Lauria, A., De Trizio, L., Azarbod, A., et al. (2015). Diffusion-driven and size-dependent phase changes of gallium oxide nanocrystals in a glassy host. PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 17(7), 5141-5150 [10.1039/c4cp05485g].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/78413
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