EVOLUTION OF PROTONIC CONDUCTION IN SOME SYNTHETIC ANIONIC CLAYS

The conductivity of some lamellar double hydroxides (LDH's) of general formula: [M(II)(1-x)M(III)x(OH)2]x+[X(x/m) .nH2O]x-(x almost-equal-to 1/3; M = Cr, Cu, Zn; X(m-) = Cl-, Br-, NO3-, 1/2CO3(2-), 1/2SO4(2-)) is studied by the complex impedances method. The measurements are performed in an airtight cell. The samples are previously equilibrated with a 50% RH atmosphere. The results of conductivity measurements show clearly that the mobility of charge carriers depends on both the nature of the intercalated anions and the hydroxylated framework composition. The protonic nature of the conduction process is controlled by potentiometric measurements at room-temperature in an electrochemical gas cell.