In recent years, Cr3+-activated phosphors have been attracting a lot of interest due to their unique optical features that can be exploited for applications ranging from lasers to optical thermometry, near-infrared (NIR) emitting phosphors for bioimaging and NIR-LEDs, to name a few. Despite the interesting optical properties shown by Cr3+-doped Ga2O3, investigations are limited only to beta-Ga2O3 and alpha-Ga2O3 polymorphs. Using mesoporous silica particles with different pore sizes between 3 nm and 22 nm as nanoreactors, cubic gamma-Ga2O3:Cr3+ spinel nanocrystals (NCs) are stabilized through confinement into the mesopores as confirmed by HR-TEM, XRPD and the photoluminescence spectral shape. A detailed spectroscopic investigation in the temperature range between 16 to 500 K allowed extrapolating the fundamental parameters in the framework of the Tanabe-Sugano diagram and comparing the values for Cr3+ in gamma-Ga2O3 with the alpha- and beta-phases. In addition, due to the confinement of the NCs into the silica structure, the phase transition to the beta-phase, conventionally occurring at about 700 degrees C, is hindered up to 1000 degrees C, improving the stability of the gamma-Ga2O3 phase.

Stabilizing cubic γ-Ga2O3:Cr3+ spinel nanocrystals by size confinement into mesoporous silica nanoreactor channels

Crozzolin, Michele;Belloni, Camilla;Tanabe, Setsuhisa;Dallo, Federico;Balliana, Eleonora;Saorin, Asia;Rizzolio, Flavio;Cristofori, Davide;Riello, Pietro;Benedetti, Alvise;Back, Michele
2024-01-01

Abstract

In recent years, Cr3+-activated phosphors have been attracting a lot of interest due to their unique optical features that can be exploited for applications ranging from lasers to optical thermometry, near-infrared (NIR) emitting phosphors for bioimaging and NIR-LEDs, to name a few. Despite the interesting optical properties shown by Cr3+-doped Ga2O3, investigations are limited only to beta-Ga2O3 and alpha-Ga2O3 polymorphs. Using mesoporous silica particles with different pore sizes between 3 nm and 22 nm as nanoreactors, cubic gamma-Ga2O3:Cr3+ spinel nanocrystals (NCs) are stabilized through confinement into the mesopores as confirmed by HR-TEM, XRPD and the photoluminescence spectral shape. A detailed spectroscopic investigation in the temperature range between 16 to 500 K allowed extrapolating the fundamental parameters in the framework of the Tanabe-Sugano diagram and comparing the values for Cr3+ in gamma-Ga2O3 with the alpha- and beta-phases. In addition, due to the confinement of the NCs into the silica structure, the phase transition to the beta-phase, conventionally occurring at about 700 degrees C, is hindered up to 1000 degrees C, improving the stability of the gamma-Ga2O3 phase.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10278/5095487
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