Density and hardness of Yttrium-doped Barium Cerium-Zirconium electrolyte types oxides

Yttrium-doped Barium Cerium-Zirconium (BCZY) types oxides is a proton-conducting ceramic electrolyte widely studied for applications in solid oxide fuel cells (SOFCs), hydrogen separation membranes, and other electrochemical devices. It is an advanced material offering a combination of high proton conductivity, chemical stability, and mechanical durability. The mechanical and material’s physical properties, particularly density and hardness are important and critical characteristics to optimize the performance of PC-SOFC. However, reaching high density frequently necessitates high sintering temperatures, which can cause grain formation and affect mechanical characteristics like hardness, decreasing the material's ability to withstand thermal stress and cracking. Meanwhile, BCZY’s hardness is difficult to precisely measure and optimize as it influences various factors such as grain size, phase purity, microstructural, and inhomogeneity which frequently leads to inconsistent or incorrect hardness assessments. This study investigates the density and hardness of BCZY pellets, which are critical mechanical and physical properties affecting the performance and durability of protonic ceramic fuel cells. The two methods, Archimedes and geometrical were employed to determine the density of the sintered BCZY pellets, while the Vicker Hardness method was used to assess mechanical strength. In this study, the two objectives listed were carried out which are: i) To study the density of BCZY pellet using the Geometrical and Archimedes methods. ii) To investigate the hardness of BCZY using Vicker’s hardness method. The results showed that the relative densities of the BCZY pellets were approximately 91.5% for Archimedes and 91.8% for the geometrical method, indicating effective densification at high sintering temperatures. The measured Vickers hardness value was 508.3 HV which is approximately 4.99 GPa, suggesting that the material possesses sufficient mechanical robustness for high-temperature applications. However, discrepancies between theoretical and experimental densities highlight the presence of residual porosity, which can affect conductivity and structural integrity. These findings highlight the importance of optimizing sintering conditions and understanding the correlation between density and hardness to enhance the mechanical stability and electrochemical performance of BCZY electrolytes.