Structural, Electrical and Electrochemical Properties of Mg0.55Si1.9Al0.1Fe0.1(PO4)3 Ceramic Electrolytes

This study was undertaken to investigate the structural, electrical and electrochemical properties of Fe3+ substituted Mg0.55Si1.9Al0.1(PO4)3 compound synthesized by water-based sol–gel technique. X-ray diffraction showed that the compound crystallized in monoclinic crystalline phase with a space group of P1 21/c1. The sample sintered at 850 ˚C exhibited the highest conductivity of 1.42 × 10-6 S cm-1 at 373 K since it contained the highest number of mobile ions. It also exhibited the highest value of ion mobility, μ of 1.13 × 10-11 cm2 V-1 s-1 at ambient temperature which was attributed to the optimum size of migration channel as indicated by its unit cell volume. Linear sweep voltammetry result showed that the Mg0.55Si1.9Al0.1Fe0.1(PO4)3 was electrochemically stable up to 3.0 V. Meanwhile, its ionic transference number of 0.99 suggested that the majority of the mobile charge carriers were mainly to ions, expected to be Mg2+ ions.