ZnAl2O4 as a potential sensor: variation of luminescence with thermal history

Abstract

ZnAl 2 O 4 spinel powders were prepared using the Pechini or co-precipitation synthetic route and were then treated at different temperatures (600-1350 °C). These powders were characterised by X-ray diffraction, scanning electron microscopy (SEM), diffuse reflectance and luminescence measurements. SEM investigations and the X-ray patterns showed that the spinel crystallite size was dependent on the synthetic route and the treatment temperature. In addition, the structural evolution was investigated by Rietveld refinements. The inversion rate decrease was correlated with the temperature, leading to a direct spinel phase for the sample treated at high temperature. Furthermore, luminescence measurements showed various emissions linked to the presence of defects in the matrix structure. The two main emissions observed were attributed to oxygen vacancy and Zn in the interstitial positions (as revealed by differential Fourier maps). The luminescence spectra exhibited strong differences between 1200 °C and 1350 °C. At the higher temperature, the characteristic emission spectra can be attributed to the direct spinel phase. The indirectdirect spinel transformation can be monitored through the change in the optical properties and correlated to the thermal history of the sample.

Effect of calcination temperature on structural and optical properties of MAl2O4 (M = Ni, Cu, Zn) aluminate spinel nanoparticles

“…Aguilar et al [18] [29][30][31] after calcination at 600 ℃. This is in agreement with previous studies by Cornu et al [20]. They also found that the amorphous precursor, obtained from the Pechini or co-precipitation synthetic route, transformed into ZnAl 2 O 4 spinel phase after heat treatment at 600 ℃.…”

“…The single phase NiAl 2 O 4 spinel powders were obtained at 1400 (unmilled powders) and 1100 ˚C (15 h milled powders) ; however, their optical properties have not been examined. Cornu et al [20] studied the luminescence properties of ZnAl 2 O 4 particles which were prepared using the Pechini or co-precipitation synthetic route and treated at different temperatures between 600 and 1350 ℃. It was found that the transformation of amorphous precursor to ZnAl 2 O 4 spinel phase occurred after heat treatment at 600 ℃ and various luminescence emissions linked to the presence of defects in the matrix structure.…”

Optical properties of Cr doped ZnAl2O4 nanoparticles with Spinel structure synthesized by hydrothermal method

“…Spinel structure metal-oxide (AB 2 O 4 ) is a kind of important functional semiconductor materials, which have attracted extensive attention due to its unique crystal structure, special properties and broad application prospect in the fields, such as catalysts, catalytic carriers, high-temperature ceramics, optical materials, sensors and dielectric materials [1][2][3][4][5][6][7], etc. In the formula AB 2 O 4 , A represents the tetrahedral position occupied by bivalent metal cations, and the tetrahedral gap formed by four oxygen ions, while B position represents the octahedral position occupied by the trivalent metal cations, and the octahedral void formed by six oxygen ions [8][9][10].…”

Thermoluminescent microparticle thermal history sensors

“…The emission and absorption characteristics of these defects are very sensitive to the local bonding environment and microstructure of the material and therefore its thermal history. Perhaps the earliest work of this type was that of Feist 19,20 , but subsequent important research has also been performed by Eilers 21 and Cornu 22 . In these methods, after a thermal event, a laser or optical parametric oscillator is used to excite carriers to the upper defect levels where a subsequent fluorescent event emits photons.…”