Highlights

Ion Beam Irradiation of Complex Ceramics

Scientific Achievement

This research project, which is supported by DOE BES, investigates radiation effects in complex ceramic materials.  The interaction of heavy-particles (alpha-recoil nuclei, fission fragments and implanted ions) with ceramics is complex because these materials have a wide range of structure types, complex compositions, and because chemical bonding is variable.  In situ TEM with ion irradiation provides an important, highly-controlled means of investigating the radiation effects in complex ceramic materials since the critical doses for each radiation-induced process under a specific set of experimental conditions (cation or anion disordering, solid state amorphization, chemical decomposition, etc.) can be determined.

We have conducted systematic ion irradiation studies of a wide variety of compositions of the pyrochlore structure-type during the past several years, and we have developed a fundamental understanding of the behavior of pyrochlore, as a function of composition, to ion beam-induced amorphization.  The effects of different material parameters on the radiation-induced amorphization and order-disordering processes have been determined.  We continue the study of this phase with the IVEM-Tandem facility and plan to conduct more experiments using ion beam irradiation with in situ TEM observation to understand the annealing behaviors of various pyrochlore compositions.  We will also extend our studies to include other complex ceramics, such as perovskite, apatite, zirconia polymorphs and zircon.

Significance

The crystalline-to-amorphous (c-a) phase transition is of fundamental importance.  The c-a transition has important technological applications because amorphous materials may have increased hardness, are more or less resistant to corrosion and oxidation, may be used in opto-electronic devices, have high magnetic permeabilities and electrical resistivities, and radiation-induced damage cascades can be used to flux pinning of high Tc superconductors.  Additionally, in the geosciences many geochronological isotopic techniques are affected by radiation damage, and in nuclear waste management, amorphization is one of the most important considerations in evaluating the long-term durability of a nuclear waste form.  Our research group has actively used the IVEM-Tandem facility for the study of this subject during the past 10 years.  Our results have been published in more than 100 research papers.

Performers