Ionic conductivity in layered Na3Mo2P2O11(OH)·2H2O
Abstract Proton and sodium conductivities of Na 3 Mo 2 P 2 O 11 (OH)·2H 2 O have been studied from 25 to 460°C. The proton conductivity ranged from ∼6×10 −6 S/cm at 26°C to ∼2×10 −5 S/cm at 60°C ( E a =32kJ/mole and and log σ 0 =0.02 S/cm). The profile of proton conductivity as a function of relative humidity is similar to a type III Brunauer adsorption isotherm and suggests that the conduction mechanism is of particle hydrate-type. The proton conductivities at 100°C are ∼5×10 −7 S/cm for RH=6% and ∼9×10 −6 S/cm for RH=100%. Sodium ion conductivity was studied in the dehydrated phase with conductivities σ 267°C ∼2×10 −7 S cm ( E a = 104 kJ mole ) and σ 457° C ∼3×10 −3 S cm ( E a = 208 kJ mole ). The proposed conduction mechanism for sodium ion conductivity is similar to that in Na-β-alumina.