Mechanical and structural properties of BaCrO4 nanorod films under confinement and shear

Using an X-ray surface forces apparatus (X-SFA) we have investigated the effects of normal load (stress) and shear on the ordering and tribological properties of 10 nm x 30 nm surfactant-coated BaCrO4 nanorods in isooctane, confined within submicrometer films. The film structure and corresponding friction forces were monitored as a function of time and shearing distance at different gap sizes and loads. The X-ray diffraction patterns indicate a cubic phase of nanorods coexisting with a surfactant phase that depends on the load, film thickness, shear rate, and shearing time. Atomic force microscopy and birefringence measurements performed on each surface after a shearing experiment showed ordered domains of nanorods over length scales of several tens of micrometers.