Sintering duration as factor in defect formation and free volume distribution in spinel-type MgAl 2 O4 ceramics

A study of MgAl₂O₄ ceramics, sintered at 1400 °C for 2, 5, and 9 h for electronic sensor use, employed X-ray diffraction, electron microscopy, mercury porosimetry, and positron annihilation lifetime spectroscopy to examine phase composition, microstructure, and porosity. Results revealed a dual-phase structure with branched grains, grain boundaries, and pores of various shapes and sizes. Longer sintering slightly reduced nanopore size and fragmented free-volume defects, while pore count remained stable. These findings highlight how sintering affects defect formation and porosity, offering insights into optimizing MgAl₂O₄ ceramics for improved performance in sensors, including humidity detection.