Nanosized Thermosensors for Use in Explosions
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Nanosized Thermosensors for Use in Explosions Hergen Eilers1, Thandar Myint1, Ray Gunawidjaja1, Jillian Horn2, James Lightstone2, Christopher Milby2, and Demitrios Stamatis2 1
Applied Sciences Laboratory, Institute for Shock Physics, Washington State University, PO Box 1495, Spokane, WA 99210 2
NSWC – Indian Head Division, 4104 Evans Way Suite 102, Indian Head, MD 20640
ABSTRACT Nanophase Eu-doped Y2(CO3)3 and Eu-doped Zr(OH)4 are seeded into explosive fireballs to record the temperatures inside the fireball. The heat from the explosion decomposes the materials and converts them into Eu-doped Y2O3 and Eu-doped ZrO2, respectively. The optical signatures of these materials are compared with those of samples heated in a pyroprobe. By comparing the full-width half-max (FWHM) of the excitation peak of Eu-doped Y2(CO3)3 or comparing the ratio of two fluorescence peaks and the peak position of Eu-doped Zr(OH)4, we are able to deduce the temperatures inside the explosive fireball. INTRODUCTION The design of explosives for the destruction of biological agents requires detailed knowledge about the temperature distribution inside the post-detonation fireball. Optical pyrometry and spectral line fitting can provide temperature data from near the surface of the fireball. Accessing information about the conditions inside the fireball requires new approaches. We recently reported on the initial development and testing of Eu-doped Y2(CO3)3 nanoparticles that were seeded into an explosive fireball.[1] The nanoparticles are collected at the end of the explosion test and subsequently analyzed. Initially, the nanoparticles are amorphous in nature and consist of carbonate precursors. Exposure to the heat inside the fireball decomposes the carbonate and converts it into an oxide. The decomposition also changes the amorphous structure of the material. The optical signature from the dopant ions provides information about the amorphous/crystalline structure of the material. This information is compared with reference samples which have been heated under controlled conditions in a pyroprobe. We have refined the synthesis conditions of the nanoparticles and eliminated several uncertainties in determining the reference data. A new set of open-chamber and closed-chamber explosion tests using nanophase Eudoped Y2(CO3)3 and nanophase Eu-doped Zr(OH)4 was conducted at the Indian Head Division, Naval Surface Warfare Center (IHDIV-NSWC). The optical signatures of these test samples were measured and their characteristic spectral peak width (Eu0.02:Y1.98(CO3)3) and fluorescence intensity ratio and peak position (Eu0.01:Zr0.99(OH)4) determined. Comparison with reference data yields the temperature that the samples were exposed to. We compare these optically determined temperatures with temperatures measured by thermocouples during the explosion.
The Eu: Y2(CO3)3 samples which rely on changes in the amorphous structure are suitable for temperatures up to near the crystallization temperature.[2, 3] Structural changes due to temperatures beyond this
