Radiation-Induced Nanostructures in an Iron Phosphate Glass
- PDF / 4,416,948 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 33 Downloads / 167 Views
R3.21.1
Radiation-Induced Nanostructures in an Iron Phosphate Glass K. Sun1,2, T. Ding1, L.M. Wang1,3 and R.C. Ewing1,3 1 Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 2 Electron Microbeam Analysis Laboratory, University of Michigan, Ann Arbor, MI 48109 3 Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 ABSTRACT Electron and ion irradiation-induced nanostructures in an iron phosphate glass with a composition of 45 mol%Fe2O3-55 mol%P2O5 have been characterized by advanced electron microbeam techniques. Analysis by energy-filtered transmission electron microscopy indicated that Fe-rich and P-rich nanophases were formed when the glass was irradiated under a broad (with a diameter of 1.2µm) electron beam [give the dose range]. Phase separation developed with the increase in electron dose (from 1.0×1026e/m2 to 4.8×1026e/m2) as a result of the formation of an Fe-rich phase and pure P-phase. The formation of the Fe-rich and the P-phases are thought to be due to mainly ionization process. Under a low energy ion beam irradiation, Fe/FeO nanoparticles were formed, as confirmed by selected-area electron diffraction analysis. However, no nanoparticles were observed under a high-energy high-dose ion irradiation. The ion beamirradiation results suggest that the formation of the Fe/FeO nanoparticles was due to preferential sputtering during ion irradiation and that the nanoparticles lie within the surface layers of the glass. INTRODUCTION Phosphate glasses are generally not chemically durable, however, the addition of Al2O3 and Fe2O3 leads to a significant improvement in its durability [1]. Thus, iron phosphate and aluminophosphate glasses have been considered as nuclear waste form glasses [2]. Electron and ion irradiation are two techniques that have been normally used for the study of radiation damage effects in nuclear waste forms [3-5]. However, studies of electron and ion beam radiation effects on the iron phosphate glass are rare. On the other hand, radiation processes that employ energetic electron or ion beams have been widely used for materials modification or to fabricate new materials. As an example, an electron beam is used in rapid thermal annealing processes by the semiconductor industry. Recently, there has been a strong interest in introducing different elements into glasses to fabricate new materials with special nonlinear optical properties [6]. For this purpose, a number of elements have been implanted into different substrates such as Cu, Zn, and Ge in silica and Au in TiO2 and SrTiO3 i.e., ion implantation plays a very important role for such a purpose. Moreover, as a group of glasses with high chemical durability originally developed as a candidate for the storage of nuclear wastes, little attention has been paid to exploiting new applications for the iron phosphate glasses. The uses of electron and ion irradiation on the glass not only provide useful data for estimating the durability of the glass under nuclear waste irradiation but
Data Loading...
