The effects of the solution reactant concentration and temperature on the preparation of Pr3+:BaF2 transparent ceramics

Barium fluoride (BaF2) crystals are attracting much attention as efficient inorganic scintillator promising for high-energy physics, industrial inspection, and other fields because of the fast component of the decay time (0.6 ns) and high radiation resistance. However, two major drawbacks limit its practical application: (i) a slow decay time of similar to 600 ns is derived from self-trapping excitons; (ii) the absolute light yield from the fast luminescence component is not competitive. The introducing of rare earth ions and preparation of BaF2 polycrystalline ceramics is considered to be effective measures to solve these bottlenecks. Pr3+ is extremely suitable as the activated ion of scintillation materials, which possess emission peaks located in visible band and the faster 5d-4f transition. In this work, highly sinterable Pr3+:BaF2 precursor powder was synthesized via the coprecipitation method by adjusting the reactant concentration and temperature. The morphology and microstructure of as-synthesized powders were characterized using scanning electron microscopy (SEM) and transmittance electron microscopy analysis. The 5 at.% Pr3+:BaF2 transparent ceramic with a transmittance of 50.7% at the wavelength of 500 nm was fabricated by hot pressing the as-prepared powders at 900 degrees C for 4 h under the axial pressure of 50 MPa. The SEM images of ceramic cross-section show that the residual pore is the main light scattering source. The absorption and emission spectrum of ceramic samples were discussed.