Nanoporous Ellipsoid Hematite Synthesized via Hydrothermal Growth

Meirong Zong and colleagues—Nshuti Cedrick, Wei Liang, Pinghua Zhu, Dongdong Liang, Haonan Liu, and Jiaxin Zou—published their findings on the growth of nanoporous ellipsoidal hematite in the European Journal of Mineralogy, volume 38, pages 575–582, in 2026 ¹.

The experiment began by subjecting an aqueous solution containing Fe²⁺ ions to high temperature and pressure for 30 minutes. At this point, iron oxyhydroxides (FeOOH) agglomerated, forming dense clusters that later evolved into needle-shaped FeOOH structures after 45 minutes of continued reaction ¹. This intermediate morphology sets the stage for subsequent phase changes.

As the hydrothermal process progressed beyond one hour, the needle-like FeOOH started dehydrating. The loss of water molecules triggered a rearrangement of the crystal lattice, gradually reshaping the material into smooth, ellipsoid particles rather than elongated needles. By 120 minutes, the system had fully transitioned to hematite, with the newly formed crystals displaying a pronounced nanoporous character throughout their volumes ¹.

Scanning electron microscopy revealed that these ellipsoids possessed pores averaging about 27 nanometers across—a size large enough to allow selective diffusion yet small enough to maintain structural integrity ¹.

These observations provide fresh insight into how hematite can be engineered at the nanoscale through careful manipulation of synthesis time and temperature. Prior models largely treated hematite as a relatively uniform mineral; Zong et al.’s work demonstrates that its microstructure can be tuned by adjusting precursor phases and reaction duration. Such control could prove valuable in applications ranging from catalysis—where surface area matters—to magnetic storage media, where grain shape influences coercivity.