Sol-gel deposited thermographic phosphors as possible thermal history coatings

On the thermal sensitivity and resolution of a YSZ:Er3+/YSZ:Eu3+ fluorescent thermal history sensor

“…A water-based paint containing an amorphous Eu doped matrix developed by the same team also showed monotonic variation in its decay time within the temperature range 373-1073 K, with excellent repeatability. Finally, other thermal history sensor coatings for high temperature based on the enhancement of crystallinity were also reported by Pilgrim et al [22] (Eu 3+ and Dy 3+ doped YAG, 573 K-1073 K) and Stenders et al [23] (Eu 3+ /Tb 3+ doped Y 2 O 3 , 973 K-1273 K).…”

Novel erbia-yttria co-doped zirconia fluorescent thermal history sensor

“…The temperature dependence of the crystallization rate constant, that follows an Arrhenius type relation [30], predicts a strong dependence on temperature of the microstructural state of the material which might thus pass on its fluorescence properties. Numerous studies carried out on the lanthanide activator ions Eu 3+ (in Al 2 O 3 [14], ZrO 2 [31], YAG [32], Y 2 O 3 [13,33,34], YVO 4 [35], CaY 2 Si 3 O 12 [36]), Er 3+ (in SiO 2 [25], GdAlO 3 [26], ZrO 2 [37], Gd 2 TiO 7 [38]), Tb 3+ (in Y 2 O 3 [14,34], Y 2 SiO 5 [12]), Pr 3+ (in PbO-Sb 2 O 3 -B 2 O 3 [39]) and Ce 3+ (in YAG [40]), have shown that their emission intensity at room temperature, initially nonexistent or weak, is greatly improved with the increase of crystallinity resulting from annealing at high temperature, typically in the range 1073-1573 K. This effect, that goes along with the sharpening of emission peaks and generally an increase of the luminescence lifetime [12-14, 32, 34, 38], results mainly from the coarsening of the average crystal size, the uniformization of the crystal field as well as the reduction of the number of crystal defects and residual organic groups acting as luminescence quenchers [12,33,34,38]. Figure 1 shows the x-ray diffraction patterns and the fluorescence spectra of the YSZ:Er 3+ phosphor powder produced by a sol-gel route at the Institut Clément Ader and CIRIMAT [21] in the initial state and after further annealing at 1373 K for 2 h.…”

“…One of the solutions under investigation over the last few years is the implementation of photoluminescent markers, whose luminescence emission properties are subjected to permanent evolutions with temperature and duration of exposure as a result of thermally activated microstructural or chemical changes occurring within the material [9][10][11][12][13][14][15][16][17][18][19]. With appropriate calibration, the changes observed in at least one luminescence characteristic can therefore be correlated back to the temperature to which the material has been subjected during a previous thermal event under controlled conditions.…”

“…With appropriate calibration, the changes observed in at least one luminescence characteristic can therefore be correlated back to the temperature to which the material has been subjected during a previous thermal event under controlled conditions. Contrary to the discrete changes typical of thermochromic paints, the evolution with temperature of the luminescence parameters may be in most cases continuous over the range of interest [12][13][14][15][16], thus allowing to monitor continuous spectrum of temperature rather than temperature thresholds. Luminescence parameters can also be measured quantitatively with no ambiguity using standard spectroscopic equipments, leading to potentially much higher resolution than thermochromic paints in the determination of temperature.…”

Understanding the power of luminescence ratiometric thermal history indicators driven by phase transitions: the case of Eu3+ doped LaVO4

“…7,8 The response to such demands is thermal history sensors, which have spawned a new field of research. 5,7,[9][10][11][12][13][14][15][16][17] In general, this type of sensor should be able to determine temperature based on irreversible changes in its properties. Thermal history paintings are a wellknown instance of such sensors.…”