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During nanoindentation of MgO, a pop-in phenomenon has been observed, that is, an abrupt increase in penetration depth at a critical load. Atomic force microscopy investigations have been performed to characterise the dislocation structure in the vicinity of the indented area. The pop-in has been found to be the first stage of plastic deformation during nanoindentation. This phenomenon is ascribed to the nucleation and further propagation of interstitial loops of dislocations beneath the indenter. A three-dimensional model for a flat ended indenter is developed.

During nanoindentation of MgO, a pop-in phenomenon has been observed, that is, an abrupt increase in penetration depth at a critical load. Atomic force microscopy investigations have been performed to characterise the dislocation structure in the vicinity of the indented area. The pop-in has been found to be the first stage of plastic deformation during nanoindentation. This phenomenon is ascribed to the nucleation and further propagation of interstitial loops of dislocations beneath the indenter. A three-dimensional model for a flat ended indenter is developed.

A nanoindentation device has been developed allowing the application of forces ranging between a few micronewtons and 100 mN with nanoindentation capabilities. The apparatus offers also very accurate positioning in the directions through the use of a high resolution tridirectional piezoelectric actuator. One of the main interests of this device is its capabability to allow fast and precise measurements in normal laboratory environment, making nanoindentation testing as simple to use as conventional hardness testing. After a short presentation of the device and its working principle, some of the methods used to derive the mechanical properties of the materials are presented and illustrated by experimental curves. Interesting features, such as the micro yielding of different materials under low applied forces, are also presented.

A nanoindentation device has been developed allowing the application of forces ranging between a few micronewtons and 100 mN with nanoindentation capabilities. The apparatus offers also very accurate positioning in the directions through the use of a high resolution tridirectional piezoelectric actuator. One of the main interests of this device is its capabability to allow fast and precise measurements in normal laboratory environment, making nanoindentation testing as simple to use as conventional hardness testing. After a short presentation of the device and its working principle, some of the methods used to derive the mechanical properties of the materials are presented and illustrated by experimental curves. Interesting features, such as the micro yielding of different materials under low applied forces, are also presented.

Thiolated self-assembled monolayers of carbohydrates may serve as useful polyvalent tools to mimic the organized presentation of such molecules at the cell surface. SAMs presenting the disaccharide maltose as a neoglycoconjugate were produced, and the structure was studied by high resolution atomic force microscopy. The molecules form highly ordered structures on a gold (111) surface, with lattice parameters determined by the linker moiety rather than the headgroup.