High Authority Two-Way Surface Form Memory

If the indent-planarization technique is to find application to optical devices or information storage media, it will be necessary to demonstrate robust performance at the nanometer scale. The maximum first-order wavelength that can be diffracted from a grating is twice the groove spacing, which must therefore be on the order of200-350 nm, although echelle and higher-order gratings may have much coarser spacing. The challenge in this case lies in the preparation of tooling with sufficient strength to withstand indentation forces. Although ruled gratings could quite conceivably be made, photolithographically-micromachined silicon, whose strength may exceed 10GPa even when surface flaws are present [Tuncay, 2006], will be evaluated for its ability to make nanoscale indents in martensitic NiTi. Tungsten metal and CVD diamond [Ritzhaupt 2005] is also amenable to photolithographic patterning and will be evaluated as tool materials for nano-scale indentation. In addition, a combined nanoindentationlnanoscratch instrument will be used for writing indents and lines on the surfaces ofNiTi to induce two-way shape memory effects. The same instrument will also be used to "erase" indents by scratching under dry and lubricated conditions to simulate planarization effects at the nanoscale. The experiments will help answer questions such as can SFM exist at nanoscale