A Comparative Study of Proton Transport Properties of Cerium (IV) and Thorium (IV) Phosphates

• Materials have been synthesized under conventional and microwave irradiation.
• Materials have been used as solid state proton conductors for the first time.
• Impedance measurement carried out and compared.

ABSTRACTIn the present endeavour, amorphous cerium phosphate (CP) and thorium phosphate (TP) have been synthesized by sol-gel method. Further, CP and TP have also been synthesized under microwave irradiation to yield CPM and TPM. The materials have been characterized for elemental analysis (ICP-AES), spectral analysis (FTIR), thermal analysis (TGA and DSC), X-ray diffraction studies, SEM, EDX and surface acidity (NH3-TPD). Chemical stability of the materials in various acids, bases and organic solvent media has been studied. The proton transport properties of these materials have been explored and compared by measuring conductance at different temperatures using an impedance analyzer. It is observed that conductivity decreases with increasing temperature in all cases and mechanism of transportation is proposed to be Grotthuss type. Trends in specific conductance of CP, TP, CPM and TPM has been compared and correlated based on cation exchange capacity values and surface acidity. Mechanism of conductance in these materials has been discussed based on conductivity (σ) data and activation energy (Ea).

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