Papers by Author: Maria Chiara Munisso

Abstract: A spatially resolved cathodoluminescence (CL) analysis is used as a means for chemical and mechanical analyses of the composite surface after environmental exposure. CL emission proves extremely efficient in concurrently monitoring the concentration of point defects (e.g., oxygen vacancies) on the material surface. Using CL, averaging effects from sub-surface parts of the material can be minimized, and the actual chemical state of the material surface is revealed. As a result, information about the stoichiometry of the material surface can be obtained directly from the lattices of the constituent phases, this enabling one to pattern relevant connections to the environmental resistance of oxide-based bioceramics. A highly fracture resistant alumina/zirconia composite represents the latest trend in ceramics for arthroplastic applications in alternative to monolithic alumina or zirconia ceramics. This composite material is designed from both chemical and microstructural viewpoints in order to prevent environmental degradation and fracture events in vivo, an important step forward in the full exploitation of ceramic materials in the field of arthroplasty. Systematically monitoring the optical activity of oxygen vacancies in both alumina and zirconia phase reveals the distinct role on the kinetics of polymorphic transformation. From the presented data an explicit role is evinced for oxygen vacancy formation in the alumina matrix in the complex cascade of mechanochemical events determining the environmental resistance of the composite.

Abstract: With the proliferation of several types and classes of high performance ceramic materials, the screening, evaluation and integration of new materials into structures and devices require a new and more effective approach. Evaluation on the nano-scale of the mechanical characteristics of new ceramic materials requires multiple complementary metrology tools. We report here about an advanced metrology tool, cathodoluminescence (CL) spectroscopy, which has a potential to rapidly screen and evaluate residual stress characteristics in advanced ceramic materials and structures. Nano-scale stress measurements are made in situ into an integrated metrology vacuum chamber in a field-emission gun scanning electron microscope (FEG-SEM). Complementing this tool, we also describe a new image analysis based on CL emission for fast screening and ranking of domain structures in ferroelastic ceramics. The end result of this paper is to show how crystallographic and mechanical characteristics of ceramics can be quantitatively characterized in a hybrid device combining electro-stimulated imaging and spectroscopic outputs.