Mechanical response of KD2xH2(1−x)PO4 crystals during nanoindentation

Abstract

The deformation behavior of rapidly grown tetragonal KD2xH2(1−x)PO4 (KDP and DKDP) single crystals, with a deuteration degree x of 0.0, 0.3, and 0.6, is studied by nanoindentation with a 1 μm radius spherical indenter. Within experimental error, the deformation behavior is found to be independent of the deuterium content and different for (001) and (100) surfaces. Multiple discontinuities (so-called “pop-in” events) in force-displacement curves are observed during indentation loading, but not during unloading. Slip is identified as the major mode of plastic deformation in DKDP, and pop-in events are attributed to the initiation of slip.