Annealing effects of triboluminescence production on irradiated ZnS:Mn W.A. Hollerman a, ⁎ , N.P. Bergeron a , S.M. Goedeke b , S.W. Allison b , C.I. Muntele c , D. Ila c , R.J. Moore a a Department of Physics, University of Louisiana at Lafayette, P.O. Box 44210, Lafayette, LA 70504 USA b Engineering Science and Technology Division, Oak Ridge National Laboratory, P.O. Box 2008, M.S. 6054, Oak Ridge, TN 37831 USA c Center for Irradiation of Materials, Alabama A&M University, P.O. Box 1447, Normal, AL 35762 USA Available online 13 March 2007 Abstract The current interest in returning to the Moon and Mars by 2030 makes cost effective and low mass health monitoring sensors essential for spacecraft development. In space, there are many surface measurements that are required to monitor the condition of the spacecraft including: surface temperature, radiation fluence, and impact. Through the use of phosphors, materials doped with trace elements that give off visible light when excited, these conditions can be monitored. Practical space-based phosphor sensors will depend heavily upon research investigating the resistance of phosphors to ionizing radiation and the ability to anneal or self-heal from damage caused by ionizing radiation. Preliminary investigations into these sensors have recently been performed using a highly triboluminescent phosphor, ZnS:Mn. This phosphor has been found to be temperature sensitive from 100 to 350 °C and responsive to both impact and radiation fluence. A 3 MeV proton fluence as small as 2.3 × 10 13 mm - 2 was found to statistically reduce the ZnS:Mn fluorescence decay time for temperatures less than 200 °C. Reductions in decay time appear to be proportional to increasing fluence. These results have stimulated research into the effects of thermal annealing on triboluminescence. While this testing is not all-inclusive; it does illuminate the process that can be used in the selection of appropriate sensor materials. © 2007 Elsevier B.V. All rights reserved. Keywords: Triboluminescence; ZnS:Mn; Ion irradiation 1. Introduction Fluorescent materials are used in a variety of applications including television screens, lighting, photocopy lamps, scin- tillators, as X-ray conversion screens and sensor technology. The materials used for these sensors are typically inorganics doped with impurities that provide characteristic fluorescence and are commonly referred to as phosphors. Sensor technolo- gies based on these materials use characteristics of the light emission to determine various parameters such as temperature, impact/pressure, and radiation dose. The development of a health-monitoring sensor suite re- quires many individual measurements that must survive and operate in the harsh environment of space. This environment includes wide temperature swings, radiation exposure of all types and energies, and particle impact. In addition, the sensors must also be lightweight and minimally intrusive. To be used in space, a phosphor must be resistant to ionizing radiation. Potentially it would be useful for some of the radi- ation damage to be annealed by a controlled temperature in- crease. In 2004, samples of a ZnS:Mn paint were exposed to 3 MeV proton fluences of 2.3 × 10 13 and 7.4 × 10 13 mm - 2 [1]. After irradiation, these samples were subjected to two thermal cycles determining fluorescence decay time versus temperature. Results from this research show that a consistent increase in the temperature dependent fluorescence decay time was observed at both fluences during the second thermal cycle [1]. The tem- perature dependent fluorescence decay time was greater during the second thermal cycle than was measured during the first. The more heavily irradiated samples did not have annealed decay times that were as large as those that received lesser radiation fluences. This result could mean that the annealing temperature was not reached or the sample did not stay at the elevated temperature long enough for complete annealing to Surface & Coatings Technology 201 (2007) 8382 – 8387 www.elsevier.com/locate/surfcoat ⁎ Corresponding author. E-mail address: hollerman@louisiana.edu (W.A. Hollerman). 0257-8972/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.surfcoat.2006.10.054