Studies on Particle Size Controlled Synthesis and Selectivity of Crystal Growth Direction of MgFe Layered Double Hydroxides

MgFe layered double hydroxides (LDH) have been synthesized at high supersaturation using a new method, involving separate nucleation and aging steps. The influence of aging temperature and aging time on the selectivity of crystal growth in different directions and the particle size of MgFe-LDH have been systematically investigated. XRD analyses show that the arrangement of layered cation in MgFe-LDH becomes more complete with increasing Mg∶Fe molar ratio. It has been shown that with increasing aging time at the same temperature, the crystallinity of MgFe-LDH increased and the particle size became larger. The same effect was observed when samples were aged at an increasing temperature for a fixed period, but the particle size of MgFe-LDH increased dramatically with the increasing aging temperature. The rate of crystal growth inadirection 110 crystalline face was found to be greater than that incdirection 002 crystalline face and the size of the crystallites in the adirection was larger than that in thecdirection under all experimental conditions.