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

Abstract

Barium fluoride (BaF 2 ) 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 ~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 BaF 2 polycrystalline ceramics is considered to be effective measures to solve these bottlenecks. Pr 3+ 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 Pr 3+ :BaF 2 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.% Pr 3+ :BaF 2 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°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.