Optical properties versus temperature of Cr-doped γ- and α-Al2O3: Irreversible thermal sensors application

Guillaume Salek (1) , Alexis Devoti (1) , Emilie Lataste (1) , Alain Demourgues (1) , Alain Garcia (1) , Veronique Jubera (1) , Manuel Gaudon (1)

1 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux

A thorough investigation by X-ray diffraction, UV–vis and luminescence spectroscopy is carried out to demonstrate how the chromium content of alumina matrices impacts the temperature of the γ→α irreversible phase transition. The Cr3+ contents influence slightly the phase transition temperature but control the brightness of the powders. Nice colorimetric contrasts from green to pink are observed between the two allotropic forms. Furthermore, drastic changes of the spectral distribution and of the intensity of luminescence are observed, thus allowing to use this pigment as a both thermochromic and luminescent thermal sensor. Additional measurements at low temperature revealed that the Cr3+ emission of the γ-Al2O3 matrix is constituted by a large band. A configurational diagram schematic approach suggested for the first time that this emission is due to spin-allowed 4T2→4A2 transition on this largely investigated γ-Al2O3 compound.

Mots clés: Alumina; Luminescence; Phase transition

Domaines: Matériaux

Guillaume Salek, Alexis Devoti, Emilie Lataste, Alain Demourgues, Alain Garcia, et al.. Optical properties versus temperature of Cr-doped γ- and α-Al2O3: Irreversible thermal sensors application. Journal of Luminescence, 2016, 179, pp.189-196. ⟨10.1016/j.jlumin.2016.07.004⟩. ⟨hal-01370332⟩