Calcium chloride addition to overcome the barriers for synthesizing new Ca-Ti layered double hydroxide by mechanochemistry

Abstract In this study, a new binary Ca-Ti layered double hydroxide (LDH) has been synthesized for the first time by a two-step (dry and wet) milling of calcium hydroxide, hydrated titanium dioxide and a third phase of calcium chloride. No reactions were observed while milling calcium hydroxide and hydrated titanium dioxide unless the further addition of a third phase of calcium chloride which triggered the solid state reaction to form LDH phase. The traditional co-precipitation process failed to synthesize Ca-Ti LDH due to the barriers of the precipitation pH and ion radius differences between Ca2+ and Ti4+. The X-ray diffraction (XRD), Thermogravimetric Analysis (TGA), X-ray photoelectron spectroscopy(XPS) and Scanning electron microscopy (SEM) techniques were applied to characterize the prepared samples. The characterization results demonstrated the successful production of high crystalline Ca-Ti LDH phase. This work proved the feasibility of mechanochemistry to produce novel binary LDH which may be of help for the synthesis of other new layered materials in general.