Analyzing indentation stress-strain response of LaGaO3 single crystals using spherical indenters

A new approach to spherical nanoindentation analyses is described and used to study the anisotropy of mechanical properties for (100) and (001) LaGaO3 single crystals. Unlike sharp indenters, indentations by spherical indenters permit the nanoindentation load-displacement curve to be converted more reliably into indentation stress-strain curves. Using a new definition of indentation strain, indentation stress-strain curves that are relatively insensitive to the radii of the indenters are presented. These curves allow the modulus of the sample to be evaluated from the elastic loading segment, instead of the common practice of approximating it from the elastic unloading segment. These measurements indicated that the (100) LaGaO3 single crystal had a higher modulus and a higher hardness compared to the (001) sample. 24 refs.