Solid state protonic conductors, present main applications and future prospects

Proton transfer and superionic conductivity in solids and gels

The alkali cations in the layered perovskites MCa 2 Nb 3 O 10 (M ≡ K, Rb, Cs) are exchanged by protons in aqueous acid in a topochemical reaction to give HCa 2 Nb 3 O 10 . The unit cell of HCa 2 Nb 3 O 10 , as determined from powder X-ray diffraction, is tetragonal with a = 3.851 A and c = 14.38 A and contains one formula unit. The anhydrous hydrogen compound hydrates to form a composition HCa 2 Nb 3 O 10 ·1.5H 2 O which is also tetragonal with a = 3.854 A and c = 16.23 A . The hydration-dehydration behavior at 24 °C as a function of the partial water pressure shows significant hysteresis as a result of the expansion and contraction of the unit cell along the c axis.

Ion Exchange of the Layered Perovskite KCa2Nb3O10 by Protons.

New layered perovskites: ABiNb2O7 and APb2Nb3O10 (A=Rb OR Cs)

The principal features of the thermodynamics and kinetics of ion-exchange processes in inorganic ion exchangers are discussed. The literature data on the ion-exchange properties of oxide systems, globular hydrates, and salts of polyvalent cations are surveyed. The methods for carrying out ion-exchange processes and the characteristic features of their occurrence on typical inorganic ion-exchange materials are examined. The bibliography includes 306 references.

https://iopscience.iop.org/article/10.1070/RC1997v066n07ABEH000348/pdf

A.D. English

Papers

New inorganic proton conductors