Figure 6

SEM micrographs of the LDH powders prepared via hydration of MMO followed by anion exchanges at different temperatures without and with application of high-power ultrasound: (a) Mg₂Al-OH_(80°C/24h), (b) Mg₂Al-OH_{(Sonic/30min)}, (c) Mg₂Al-Cl_{(25°C/15min)}, (d) Mg₂Al-Cl_(Sonic/4min), (e) Mg₂Al-H₂PO_{4 (25°C/1h)} and (f) Mg₂Al-H₂PO_{4(Sonic/8min)}.