June 28, 2024
Research Highlight

Ionizing Radiation Stabilizes Gibbsite and Boehmite against Decomposition

When exposed to a sufficiently high dose of ionizing radiation, gibbsite and boehmite are less susceptible to dehydration-induced breakdown

This illustration shows red-and-blue molecules being hit by radiation and an upward arrow showing the dehydration.

Irradiated boehmite and gibbsite nanoparticles had higher activation energies (Ea,I) for thermal decomposition than the activation energies of their pristine counterparts (Ea,P). This increased stability could be attributed to the decreased hydrous nature of the samples after radiation exposure.

(Image by Nathan Johnson | Pacific Northwest National Laboratory)

The Science

Effectively and safely processing nuclear waste involves understanding how ionizing radiation interacts with materials, especially in extreme environments. This study investigated how gamma radiation affects the thermodynamic stability of gibbsite and boehmite, showing that their composition and morphology did not change after irradiation, but both materials experienced reduced mass loss due to decomposition caused by dehydration. Quantitative analyses of thermal mass loss behavior also demonstrated that irradiated boehmite and gibbsite nanoparticles had higher activation energies than their pristine counterparts, with the extent of the increase dependent on the total dose. This increased stability may be due to the decreased hydrous nature of the samples after radiation exposure.

The Impact

Aluminum is a common component of nuclear fuel rod casings. Boehmite and gibbsite, two of the most abundant aluminum (oxy)hydroxide minerals on Earth, also comprise over 70% of the approximately 60,000 metric tons of legacy radioactive tank waste at the Department of Energy’s Hanford Site. These materials have since experienced decades of continuous exposure to background beta and gamma radiation from decaying radionuclides, including cesium-137 and strontium-90. The ionizing radiation modifies their thermodynamic stability and surface charges while not significantly affecting the bulk structure. A fundamental understanding of the effects that ionizing radiation has on materials will inform the safe storage of nuclear waste over the timescales required for processing and disposal. This study contributes key information about the stability of boehmite and gibbsite, helping fill these knowledge gaps.


This study examined how gamma radiation affects the stabilities of two materials—gibbsite (aluminum hydroxide) and boehmite (aluminum oxyhydroxide) nanoparticles—related to their thermal decomposition. Using X-ray diffraction analysis and scanning electron microscopy imaging techniques, scientists observed that irradiation did not cause any major changes in either composition or morphology. They also showed that both materials experienced decreased mass loss after irradiation, as observed using thermogravimetric and differential scanning calorimetry. In addition, spectra from other techniques including Raman and attenuated total reflectance-Fourier transform infrared spectroscopies suggested that radiation selectively cleaved some of the hydroxyl in both the boehmite and gibbsite, mostly at the surface of the nanoparticles. Further analysis showed that irradiated boehmite and gibbsite had higher activation energies for thermal decomposition than non-irradiated samples, and the magnitude of the increase depended on the level of radiation dose. Overall, the results of this work indicate that a sufficient dose of ionizing radiation makes boehmite and gibbsite nanoparticles less susceptible to dehydration-induced decomposition, possibly because the samples are less hydrous after radiation. Finally, an amorphous phase on the surfaces of the nanoparticles—also caused by the radiation—seems to impart further and long-lasting thermodynamic stability.


Ping Chen, Pacific Northwest National Laboratory, ping.chen@pnnl.gov

Xin Zhang, Pacific Northwest National Laboratory, xin.zhang@pnnl.gov

Carolyn Pearce, Pacific Northwest National Laboratory, carolyn.pearce@pnnl.gov


This research was supported by IDREAM (Interfacial Dynamics in Radioactive Environments and Materials), an Energy Frontier Research Center funded by the Department of Energy (DOE), Office of Science, Basic Energy Sciences program (FWP 68932).

A portion of this research was performed with the user proposals 51382 and 51922 at the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the DOE Biological and Environmental Research program and located at Pacific Northwest National Laboratory (PNNL). PNNL is a multiprogram national laboratory operated for DOE by Battelle Memorial Institute under Contract DE-AC05-76RL0-1830.

R.B. and X.G. acknowledge support through the Nuclear Science Center User Facility and Alexandra Navrotsky Institute for Experimental Thermodynamics at Washington State University.

Published: June 28, 2024

Chen, P., Y. Zhu, R. Bergman, S. Xue, Y. Zhao, J. A. LaVerne, X. Guo, C. I. Pearce, Z. Wang, T. Chen, K. M. Rosso, and X. Zhang. 2024. “Effects of ionizing radiation on the thermodynamic stability of boehmite and gibbsite,” The Journal of Physical Chemistry C, 128, 8, 3578-3587. [DOI: 10.1021/acs.jpcc.3c08456]