Catalysis

Pure mathematics

Materials science

Chromatography

Field (mathematics)

Crystal structure

Electronic structure

Biochemistry

Boltzmann constant

Physical chemistry

Thermodynamics

Physics

Organic chemistry

Mathematics

Doping

Condensed matter physics

Analytical Chemistry (journal)

Crystallography

Chemistry

Optoelectronics

Advanced Optical Materials

The performance of luminescent Cr 3+ ‐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 Cr 3+ ‐based thermal sensors avoiding trial‐and‐error procedures. In this view, as prototypes, the electronic structure and the thermometric performance of Cr 3+ ‐doped α‐Ga 2 O 3 and β‐Ga 2 O 3 polymorphs are compared. Combining a detailed theoretical and spectroscopic investigation, the electronic configuration and the crystal field (CF) acting on the Cr 3+ in α‐Ga 2 O 3 are described for the first time and compared with β‐Ga 2 O 3 :Cr 3+ polymorph to discuss the thermometric behavior. A linear relationship between the 4 T 2 – 2 E 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 Cr 3+ ‐based Boltzmann thermometers. In addition, as a proof of concept, particles of β‐Ga 2 O 3 :Cr 3+ thermometer are used to locally measure in operando thermal variations of Pt catalysts on β‐Ga 2 O 3 :Cr 3+ support during a catalytic reaction of C 2 H 4 hydrogenation in a contactless and reliable mode, demonstrating their real potentials.

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