AC Electrical Properties of a NiFe-Layered Double Hydroxide with an Exceptionally Low Charge Density
Tosapol Maluangnont, Saichon Sriphan, Kanokwan Chaithaweep, Naratip Vittayakorn, Rattanawadee Ploy Wijitwongwan, Makoto Ogawa
Abstract
High Resolution Image Download MS PowerPoint Slide Single-phase NiFe-layered double hydroxides (LDHs) with low and high charge densities [CD, 0.85 vs 3.23 nm –2; Fe III /(Ni II + Fe III ) = 0.05 and 0.25] were successfully prepared via urea-assisted coprecipitation in aqueous glycerol under hydrothermal conditions. The low-CD NiFe-LDH showed decreased apparent activation energies of water evaporation and of glycerol thermal decomposition, suggesting diminished intercalate/layer interactions relative to the high-CD one. The alternating current properties of the two samples were investigated on frequency and temperature domains by several formalisms that highlight distinct electrical components. We found that the low-CD NiFe-LDH exhibited smaller static dielectric permittivity and slower relaxation time, and it was less conducting than the high-CD analog. Complex plane analyses revealed the temperature dependence of resistance and capacitance at grain and grain boundary, varying by 7–10 orders of magnitude due to water loss and glycerol loss (∼9.5 and 11.3 wt %, respectively). Our work provides insights into intercalate dynamics in a low charge density LDH, which is difficult to obtain so far, from ambient to elevated temperatures (RT–250 °C) prior to decarbonation and layer collapse.