Microwave-assisted hydrothermal synthesis and spectroscopic characteristics of a Lu₄Hf₃O₁₂:Pr scintillator

Abstract

Exclusively high density of Lu 4 Hf 3 O 12 makes it an attractive host for scintillator materials. This paper presents the versatility of microwave-assisted hydrothermal technology (MAH) to fabricate nanocrystalline Lu 4 Hf 3 O 12 :Pr luminescent powder. It is shown that by varying the parameters of the fabrication procedure, changing the composition of the liquid medium and/or using polyethylene glycol, PEG 2000, as a surfactant, the morphology of the powders could be modified. In the presence of PEG, obtaining non-agglomerated particles $5 nm in diameter was possible. Sintered ceramics at 1700 C were fabricated using various powders. Photoluminescence and X-ray excited emission spectra showed the Pr 3+ emission resulting from 4f / 4f transitions. At room temperature the 3 P 0 and 1 D 2 levels contributed roughly equally to the total emission in both the powders and sintered ceramics. The former produced luminescence with a decay time of $15 ms while the latter was an order of magnitude slower. At 10 K the emission resulted almost exclusively from the 3 P 0 level. In addition, a broad-band blue luminescence was observed at low temperatures. Room temperature radioluminescence (RL) was found to be rather inefficient in both the powders and ceramics.