Characterization of manganese-activated magnesium fluorogermanate with regards to thermographic phosphor thermometry

Abstract

Apart from the temperature, four parameters were investigated for their impact on the phosphorescence characteristics of Mg 4 FGeO 6 :Mn with regards to phosphor thermometry: the dopant concentration, the laser pulse energy, gas compositional and pressure effects as well as irreversible changes due to heat treatments. Five specially produced phosphors with different dopant concentrations as well as commercially available Mg 4 FGeO 6 :Mn were investigated in the form of coatings and pure powder. The phosphorescence was excited by the third harmonic of a pulsed Nd:YAG laser (355 nm). The lifetime decay as well as the emission spectra of the subsequently emitted phosphorescence were determined. Generally, the decay time decreased with increasing dopant concentration, with increasing laser pulse energy and for coatings also with increasing maximum temperature and duration of heat treatments, whereas the impact of the laser power was minimized by a modified evaluation routine of the decay time. Gas compositional and pressure effects did not have a significant influence on the decay time of Mg 4 FGeO 6 :Mn. Neither the variation of the dopant concentration nor the exposure to heat treatments influenced the shape of the emission spectra in any way.

Phosphor thermometry on a rotating flame holder for combustion applications

“…Therefore, we chose the commercial powder Mg 4 FGeO 5,6 ∶Mn (Osram SV067), which has an operating range from 300 to more than 900 K , corresponding to phosphor lifetimes from 3.3 ms to 5 μs (Brubach et al 2008). The median diameter of the particles lies between 5.8 and 10.5 μm .…”

“…This level is in the linear range for the response of the coating and is low enough to prevent thermal damage (Atakan and Roskosch 2013;Linden et al 2009). The PM is equipped with neutral density filters to prevent photocathode saturation (Brubach et al 2008), and a set of colored optical filters: residuals from the laser excitation are removed with a high-pass filter (CVI LPF-550). The phosphorescence signal is transmitted by means of a narrow band-pass filter (CVI F10-660) at 660 ± 10 nm .…”

Evaluation of the in-depth temperature sensing performance of Eu- and Dy-doped YSZ in air plasma sprayed thermal barrier coatings

“…For the YSZ:Dy specimens, the slope of the slower decay curve was used for temperature measurement, as the black dash lines show ( Fig.2 (inset)). Because the values obtained from the exponential fits can be sensitive to the choice of the start and end of fitting window, a precisely defined time window is required which is only related to the decay time and independent of the settings of the acquisition system, as described by the previous work [29][30][31][32]. In this study, the fitting window starts at and ends at 0.5 times and 4.5 times of decay time, respectively, which yielded good results [31].…”

A survey of phosphors novel for thermography

“…[16]. Behind the pinhole, the light was paralleled by a planar-convex lens and detected by a photomultiplier tube after passing an interference filter, which was individually adapted to the emission spectra of the respective phosphor (Section 5.2).…”