K. FirmanY. FengT.Z. Alvin LimV. RamanC.C. KhawS. GhotekarH.C. Ananda MurthyK.Y. ChanM. LuJ. SunD. ZhouK.B. Tan2025-10-232025-10-232025-0810.1016/j.jics.2025.101865https://dspace-cris.utar.edu.my/handle/123456789/11544Herein, we report a comprehensive study on the chemical modification of Bi3TaO7 fluorites through rare-earth element doping to enhance their structural and ionic conductivity. Selected dopants including La3+, Nd3+, Gd3+, Er3+ and Yb3+ were introduced to replace Ta5+ for the synthesis of novel solid solutions through solidstate reaction. Despite identical oxidation states and similar ionic radii, the solid solution formation was limited, with secondary phases observed. The lanthanide-doped Bi3TaO7 solid solutions exhibited improved ionic conductivity, particularly Bi3Ta0.8Nd0.2O6.8, which demonstrated the highest conductivity of 9.26 x 10(-3) S cm(-1) at 650 degrees C. Furthermore, this study highlights the role of oxygen vacancies and crystal defects in enhancing ionic conduction, providing further insights into the development of efficient oxide ionic conductors for applications in solid oxide fuel cells and sensor technologies.enELECTRICAL-PROPERTIESELECTROLYTESBI2O3-NB2O5SUBSTITUTIONBI2O3-TA2O5OXIDESPHASESjournal-article