Cr-doped YAlO3 phosphor crystals have been grown and characterized for applications in fiber-optic thermometers based on the temperature dependence of the photoluminescence (PL) lifetime. PL peaking at λ=735 nm is observed from the crystals following an excitation by a light-emitting diode at λ=520 nm. Long PL lifetime (τ=43.14 ms) is observed from Cr-doped YAlO3 at room temperature as compared with those of ruby (τ=4.2 ms) and spinel (τ=8.0 ms). The temperature coefficient (−0.075 ms/K) of Cr-doped YAlO3 is also larger than those of ruby (−0.010 ms/K) or spinel (−0.037 ms/K). YAlO3 is considered to be a sensitive sensor head material for fiber-optics thermometers.
Articles you may be interested inDevelopment of erbium-doped silica sensor probe for fiber-optic fluorescence thermometer Rev. Sci. Instrum. 76, 094902 (2005); 10.1063/1.2038508 Fiber-optic thermometer using Cr-doped YAlO 3 sensor head Rev. Sci. Instrum. 74, 3883 (2003); 10.1063/1.1589582 Fabrication of ruby sensor probe for the fiber-optic thermometer using fluorescence decay Rev. Sci. Instrum. 73, 3656 (2002);
Ruby single crystals have been grown successfully from the melt droplet on the sapphire crystal fibers as the sensor head directly coupled with optical fiber for the thermometer applications using fluorescence decay. In this fabrication process, droplets of slurry of ruby powders are formed on the end of the sapphire crystal fiber and are dried, sintered, and then melted and solidified in a floating-zone furnace. The photoluminescence (PL) lifetime of the ruby sensor head varies from τ=3.8 to 2.5 ms with the Cr3+ concentrations from 0.07 to 1.0 at. %. The ruby crystal with a Cr3+ concentration of 0.35 at. % is found to be the most suitable sensor head having the longest PL lifetime. The temperature coefficient of the fiber-optic thermometer equipment using the directly coupled ruby sensor head with a Cr3+ concentration of 0.35 at. % is −12.4 μs/K.
Development of erbium-doped silica sensor probe for fiber-optic fluorescence thermometer Rev. Sci. Instrum. 76, 094902 (2005); 10.1063/1.2038508 Low temperature fluorescence thermometer application of long afterglow phosphorescent Sr Al 12 O 19 : Eu 2 + , Dy 3 + crystals Rev. Sci. Instrum. 76, 084901 (2005); 10.1063/1.1988147 Fiber-optic thermometer using Cr-doped YAlO 3 sensor head Rev. Sci. Instrum. 74, 3883 (2003); 10.1063/1.1589582 Fabrication of ruby sensor probe for the fiber-optic thermometer using fluorescence decay Rev. Sci. Instrum. 73, 3656 (2002);Long duration phosphorescent SrAl 2 O 4 phosphors doped with various auxiliary activators ͑Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu͒ have been evaluated for the fiber-optic thermometer application. In this thermometer, temperature was measured based on the temperature dependence of the lifetime and/or intensity of the afterglow phosphorescence which was dominated by the thermal excitation of trapped carriers. Characteristics of the long phosphorescent fiber-optic thermometer are quite different from those of the conventional thermometer using fluorescent lifetime of the phosphors. Lifetime and intensity of the afterglow phosphorescence from the long afterglow phosphorescent sensor heads show large positive temperature coefficients in the narrow temperature region around room temperature. Sensitivity and temperature range of the long phosphorescent fiber-optic thermometer depend strongly on the trap depth and the trap density of phosphors. Since the trap depth and the trap density vary with auxiliary activator elements, a variety of fiber-optic thermometers with high sensitivity in various temperature ranges will be able to be developed using Eu 2ϩ doped SrAl 2 O 4 codoped with various auxiliary activator Ln 3ϩ ions ͑LnϭY,
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