Colloidal synthesis of BaF2 nanoparticles and their application as fillers in polymer nanocomposites

Nanoparticles of pure and Eu-doped BaF₂ have been prepared through sol-gel colloidal synthesis. In addition, BaF₂-filled PMMA polymer nanocomposites were fabricated and dielectric properties were measured. The as-synthesized pure and Eu-doped BaF₂ nanoparticles were analyzed by both X-ray diffraction and transmission electron microscopy and consisted of crystalline BaF₂ particles with an average diameter of 13.6 nm with a standard deviation of about ±2.4 nm. The photoluminescence properties of the pure and Eu-doped (2%, 4% and 8%) nanoparticles showed characteristic emission of Eu³⁺ (⁵D₀→⁷F _J (J=1–4) transitions). We also measured significantly enhanced dielectric breakdown strength of up to 30% for BaF₂ nanocomposites over the unfilled PMMA polymer. This study thus offers some promise of sol-gel synthesis of nanocomposite dielectrics with great potential for use as electrical insulation materials in cryogenic high-voltage applications.