Nan He1
University of Hong Kong1
Material-based actuation systems have been an emerging field of interest because of their direct and simple mechanism without the need to use bulky and complicated hydraulic, electric or magnetic motors. Material-based actuators utilize external stimuli such as light, temperature or humidity to drive mechanical movements. In recent research studies, transition metal oxides/hydroxides (TMOs) were introduced and studied for light-induced actuation based on their simple and effective photothermal mechanism for water de-intercalation from the turbostratic crystal structures of these materials. Turbostratic phases of nickel hydroxide/oxyhydroxide (NHO) have been found to be high-performing multi-stimuli driven actuating materials. However, these material phases are known to be unstable, and over time they become crystallized and lose their actuating properties. In this work, aluminium doping is used to stabilize the turbostraticity and actuation performance. Visible-light actuation experiments are conducted on NHO samples with and without aluminium doping to characterize their actuation performance over time. Turbostraticity is examined and quantified by techniques including XRD, Raman spectroscopy and high resolution TEM, via information such as d-spacings, intensity ratio and band peak changing. The turbostraticity difference between aluminium-doped and pure NHO actuators is correlated with their actuation performances.