Coordination interaction of Gd metal–organic frameworks and bismuth halides for efficient X-ray shielding

Abstract

X-ray radiation is widely used in industry, medicine, and space engineering, but its potential hazards necessitate effective shielding materials to protect both humans and the environment. Although lead (Pb) has been the conventional choice due to its high density (∼11.5 g cm⁻³) and atomic number (Z = 82), concerns over toxicity and weight have driven the search for alternative materials, including metal/metal oxide–polymer composites. Here, for the first time, we report the development of novel non-lead X-ray shielding nanocomposites by integrating a gadolinium-based metal–organic framework (Gd-MOF) with bismuth halides. The synthesized Gd-MOF and Gd-MOF/PDMS/BiI₃ composites were characterized using XRD, FT-IR, HR-TEM, XPS, BET, and FE-SEM with EDX mapping. XRD confirmed the presence of Gd at the (100) plane, while FT-IR identified O–H, CC, and C–H bonds, verifying successful MOF synthesis. The Gd-MOF exhibited a surface area of 158.3 m² g⁻¹, and SEM revealed uniform dispersion of Gd-MOF and BiI₃ within the PDMS sponge. The resulting composite is lightweight, flexible, and environmentally friendly. By combining the high shielding efficiency of bismuth halides with the porous structure of Gd-MOF, the 3 mm-thick sponge achieved X-ray attenuation efficiencies of ∼94% at 60 kV and 78% at 100 kV. With a low density of 1.21 g cm⁻³ and a simple fabrication process, this composite represents a promising non-toxic alternative to conventional heavy-metal shielding materials.