The performance of luminescent Cr3+-doped thermometers is strongly influenced by the locally surrounding ligand field. A universal relationship between the thermometric performance and structural/chemical parameters is highly desirable to drive the development of effective Cr3+-based thermal sensors avoiding trial-and-error procedures. In this view, as prototypes, the electronic structure and the thermometric performance of Cr3+-doped α-Ga2O3 and β-Ga2O3 polymorphs are compared. Combining a detailed theoretical and spectroscopic investigation, the electronic configuration and the crystal field (CF) acting on the Cr3+ in α-Ga2O3 are described for the first time and compared with β-Ga2O3:Cr3+ polymorph to discuss the thermometric behavior. A linear relationship between the 4T2–2E energy gap (directly linked to the relative sensitivity) and the CF strength Dq is demonstrated for a wide variety of materials. This trend can be considered as a first step to set guiding principles to design effective Cr3+-based Boltzmann thermometers. In addition, as a proof of concept, particles of β-Ga2O3:Cr3+ thermometer are used to locally measure in operando thermal variations of Pt catalysts on β-Ga2O3:Cr3+ support during a catalytic reaction of C2H4 hydrogenation in a contactless and reliable mode, demonstrating their real potentials.

Boltzmann Thermometry in Cr3+-Doped Ga2O3 Polymorphs: The Structure Matters!

Back M.
;
2021-01-01

Abstract

The performance of luminescent Cr3+-doped thermometers is strongly influenced by the locally surrounding ligand field. A universal relationship between the thermometric performance and structural/chemical parameters is highly desirable to drive the development of effective Cr3+-based thermal sensors avoiding trial-and-error procedures. In this view, as prototypes, the electronic structure and the thermometric performance of Cr3+-doped α-Ga2O3 and β-Ga2O3 polymorphs are compared. Combining a detailed theoretical and spectroscopic investigation, the electronic configuration and the crystal field (CF) acting on the Cr3+ in α-Ga2O3 are described for the first time and compared with β-Ga2O3:Cr3+ polymorph to discuss the thermometric behavior. A linear relationship between the 4T2–2E energy gap (directly linked to the relative sensitivity) and the CF strength Dq is demonstrated for a wide variety of materials. This trend can be considered as a first step to set guiding principles to design effective Cr3+-based Boltzmann thermometers. In addition, as a proof of concept, particles of β-Ga2O3:Cr3+ thermometer are used to locally measure in operando thermal variations of Pt catalysts on β-Ga2O3:Cr3+ support during a catalytic reaction of C2H4 hydrogenation in a contactless and reliable mode, demonstrating their real potentials.
2021
9
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10278/3743311
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