Issue 29, 2024

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

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 β-Ga2O3 and α-Ga2O3 polymorphs. Using mesoporous silica particles with different pore sizes between 3 nm and 22 nm as nanoreactors, cubic γ-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 γ-Ga2O3 with the α- and β-phases. In addition, due to the confinement of the NCs into the silica structure, the phase transition to the β-phase, conventionally occurring at about 700 °C, is hindered up to 1000 °C, improving the stability of the γ-Ga2O3 phase.

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

Supplementary files

Article information

Article type
Paper
Submitted
04 Apr 2024
Accepted
17 Jun 2024
First published
18 Jun 2024
This article is Open Access
Creative Commons BY license

J. Mater. Chem. C, 2024,12, 10929-10941

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

M. Crozzolin, C. Belloni, J. Xu, T. Nakanishi, J. Ueda, S. Tanabe, F. Dallo, E. Balliana, A. Saorin, F. Rizzolio, D. Cristofori, P. Riello, A. Benedetti and M. Back, J. Mater. Chem. C, 2024, 12, 10929 DOI: 10.1039/D4TC01386G

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