Pukyong National University

Pukyong National University Develops Lead-Free X-ray Shielding Aerogel

- 3D photon cage structure achieves up to 97% X-ray absorption efficiency

- Published in world-renowned chemistry journal Advanced Functional Materials

Professor Kim Jeong-hwan’s team at Pukyong National University (Department of Advanced Materials System Engineering) has developed a next-generation X-ray shielding aerogel material that is flexible, super-elastic, and hydrophobic.

X-ray technology is widely used in fields such as medicine, science, industry, and the military, but exposure to X-rays poses potential risks to the human body.

The lead (Pb)-based shielding materials currently in widespread use have several limitations, including toxicity, environmental hazards, and poor flexibility. In particular, lead exhibits low X-ray absorption efficiency in the 40？88 keV range and is inadequate in blocking secondary radiation generated by interactions between X-rays and the shielding material.

Although various studies have sought to overcome these limitations, most existing research has focused on two-dimensional (2D) flexible thin-film alternatives to lead. However, these approaches have been constrained by limited attenuation cross-sections, which fundamentally restrict the improvement of X-ray absorption performance.

Recognizing this, Professor Kim Jeong-hwan’s team focused on three-dimensional (3D) porous aerogels, which possess low density and high flexibility. Within their complex pore networks, repeated photon absorption, scattering, and reabsorption increases photon dwell time, significantly enhancing absorption efficiency.

By applying a gadolinium (Gd)-based phase separation-induced strategy, the team successfully developed a flexible aerogel with a 3D “photon cage” structure. They further enhanced the material by adding a polydimethylsiloxane (PDMS) coating and incorporating a perovskite compound, Cs₃Bi₂I？. As a result, they created a next-generation X-ray shielding material with excellent properties―super elasticity, hydrophobicity, thermal insulation, and freeze resistance―while achieving four synergistic X-ray absorption mechanisms.

The aerogel developed by the research team demonstrated excellent X-ray shielding performance across a wide energy range, thanks to the synergistic effects of its four complementary absorption mechanisms and the photon cage structure. In experimental tests, the material achieved a high X-ray absorption efficiency of 76？97% within the tube voltage energy range of 40？120 kV.

To assess the aerogel’s real-world applicability in medical environments, the research team conducted joint performance verification tests using CT equipment in collaboration with Samsung Medical Center.

Professor Kim Jeong-hwan stated, “This achievement proposes a new structural design paradigm for developing high-efficiency, lightweight, and flexible X-ray shielding materials, and holds great potential for future applications in medical, military, and industrial fields.”

The study was supported by the Ministry of Science and ICT, the Ministry of Education, and the National Research Foundation of Korea, as well as by the Global Joint Research Program at Pukyong National University. The results were published in the prestigious international chemistry journal <Advanced Functional Materials> (Impact Factor=19), under the title ‘Photon-Cage-Structured Aerogels with Quadruple Complementary Compounds for Efficient X-ray Absorption’.