Transparent X-ray Shielding Solutions with Various Metal Ions

We fabricated transparent, Pb-free X-ray shielding materials using solvated ions in a polar solvent. Previous materials have been based on dispersions of metal-containing particles such as barium sulfate (BaSO₄) in a matrix. Comparisons of suspensions of metal-based particles and solutions of metal ions in a solvent enable better understanding of interactions such as reflection, scattering, and absorption between X-rays and substances. The X-ray shielding properties of a solution of solvated metal ions were similar to or better than those of suspensions of metal-containing particles. In addition, the metal-ion solutions exhibited high transparency. The most effective material among those investigated for X-ray shielding was barium bromide (BaBr₂), which exhibits high solubility in polar solvents. X-ray shielding of 92% was confirmed at a tube voltage of 120 kV, along with ∼90% UV transmittance at a visible-light wavelength of 400 nm. Thus, both high X-ray shielding performance and high transparency were achieved.