Enhanced sinterability and conductivity insights of Nb2O5 - Doped 8 mol% yttria-stabilized zirconia: Implications for low-temperature ceramic electrolytes

• Published in: Ceramics international Vol. 50; no. 22; pp. 48222 - 48233
• Main Authors: Momin, Naeemakhtar, Manjanna, J., Kobayashi, Satoru, Aruna, S.T., Senthil Kumar, S., Sabale, Sandip, Keri, Rangappa S.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15-11-2024
• Subjects: Electrolyte; Impedance; Mechanochemical synthesis; Niobia-doped 8YSZ; Oxide-ion conductivity; Niobia-doped 8YSZ; Electrolyte; Impedance; Oxide-ion conductivity; Mechanochemical synthesis
• ISSN: 0272-8842
• DOI: 10.1016/j.ceramint.2024.09.172

The study explored the effect of incorporating niobia (Nb2O5) at 1, 3, and 5 wt percent into 8 mol% yttria-stabilized zirconia (8YSZ), made through a mechanochemical process. Niobia-doped 8YSZ samples were synthesized by a mechanochemical process and analyzed with methods including XRD, XPS, UV–Visible spectroscopy, particle size analysis, BET surface area analysis, FESEM-EDX, and EIS. Sintering was achieved at a reduced temperature of 1373 K, and all niobia-doped samples predominantly exhibited a tetragonal phase. Electrochemical impedance spectroscopy indicated that niobia doping inversely affected oxide ion conductivity-higher dopant concentrations resulted in lower conductivity. Nb-doped 8YSZ also displayed lower activation energy for conductivity compared to high-temperature (1473 K) sintered undoped 8YSZ, demonstrating equivalent performance. The combined benefits of lower sintering temperatures and enhanced ionic conductivities highlight crucial progress in developing cost-effective and energy-efficient electrolytes for clean energy applications.
•Niobium pentoxide stabilizes the 8YSZ matrix, enhances densification and grain growth.•Intragranular conductivity affected by niobia doping, not grain boundary conductivity.•Nb2O3-doped 8YSZ performs similar to undoped at higher sinter temperatures, suggesting efficient lower temperature sintering.•The role of Nb5+ suggested to involve lattice distortion and phase alterations.•Optimal balance between low sintering temperatures and high ionic conductivity hard to achieve, with less than 1 % niobia doping aiding in converting 8YSZ to a cubic phase.
This study assesses how niobia (Nb2O5) affects the ionic conductivity of 8 mol% yttria-stabilized zirconia (8YSZ) when added at 1, 3, and 5 wt%. Despite niobia's ability to lower the sintering temperature to 1373 K, it inversely impacts ionic conductivity, with greater doping resulting in reduced conductivity. However, niobia-doped 8YSZ shows lower activation energy for conductivity compared to undoped 8YSZ sintered at temperatures of 1473 K. This suggests that lower sintering temperatures can be used without undermining performance. Yet, the challenge remains to balance the improved sinterability with achieving optimal ionic conductivity, a critical factor for solid electrolytes in clean energy technologies.