The characterization of Y₂O₂S:Sm powder as a thermographic phosphor for high temperature applications

Abstract

Thermographic phosphors may be used to measure surface temperatures in hostile and high temperature environments and have applications in gas turbine combustors and high temperature regions of the turbine. Most phosphors are excited by UV light and exhibit a temperature sensitive exponential decay in emission once excitation has ceased. This can be characterized using a photomultiplier enabling temperatures to be measured at discrete points on the surface. However, one phosphor, YAG:Dy, is known to exhibit temperature sensitivity in the relative intensity of specific lines in its emission spectrum. Emission intensity can be recorded as an image using a CCD camera and hence this type of response can lead to the measurement of surface temperature distributions. In the paper the energy level characteristics of Dy leading to the intensity ratio response are discussed. Another lanthanide, Sm, is shown to exhibit similar characteristics and has been experimentally investigated using Y2O2S:Sm powder. Y2O2:Sm has been shown to exhibit intensity ratio sensitivity over a temperature range from room temperature to 1100 K and to be suitable for temperature measurement by this means with an uncertainty of approximately ±1%. It has also been shown to exhibit lifetime decay sensitivity over the temperature range from 900 to 1425 K and to be suitable for temperature measurement by this means with an uncertainty of approximately ±1%. In both cases the upper temperature limit is a function of the instrumentation used and the dynamic response may extend further. Decay time constants for Y2O2S:Sm are very short (3 µs at 1400 K), compared to those for YAG:Dy, making it suitable for use on moving surfaces by either response mode. This material, or other Sm doped phosphors, may therefore be useful for surface temperature measurement on rotating turbine blades.

Two-color thermosensors based on [Y $$_{1-x}$$ 1 - x Dy $$_x$$ x (acetylacetonate) $$_3$$ 3 (1,10-phenanthroline)] molecular crystals

“…To understand why the energy difference measured in this study (and seen in the literature [24,28,[43][44][45][46]84]) differs from the the value determined using the peak wavelengths, we note that the peak spacing (455 nm vs. 482 nm) does not directly represent the spacing between the 4 I 15/2 and 4 F 9/2 energy levels. In reality each broad spectral peak consists of multiple overlapping smaller peaks that arise due to transitions from the excited state into the Stark-split 6 H 15/2 ground state [45,85].…”

CVD of Thin Ruby Films on Si(100) and Stainless Steel for Surface Temperature Sensor Applications

“…Basic concepts of this method are given in the literature. [5] Until now, mainly rare earth-doped ceramics have been successfully used as surface-temperature sensors, [5,6] because the phosphorescence decay time of these materials is relatively long and therefore easily measurable. Nevertheless, chromium-doped aluminum oxide (ruby) also seems to be a promising candidate.…”

Photoluminescence studies of red-emitting NaEu(WO4)2 as a near-UV or blue convertible phosphor

“…In order to clarify the energy transfer between Eu 3+ and Sm 3+ ions, Sm-doped scheelite-like material NaY 0.94 Sm 0.06 (WO 4 ) 2 was also prepared, which on excitation at 404 nm exhibits four main emission bands around $565, $599, $607 and $646 nm (not shown). These emission bands can be attributed the 4 G 5/2 -6 H 5/2 , 4 F 3/2 -6 H 9/2 , 4 G 5/2 -6 H 7/2 , 4 F 3/2 -6 H 11/2 transitions of Sm 3+ ions [12]. The excitation spectrum of NaY 0.94 Sm 0.06 (WO 4 ) 2 monitoring 599 nm emission is also presented in Fig.…”