Spectroscopic Studies of Nanopowder and Nanoceramics La2Hf2O7:Pr Scintillator

Abstract

Sintered nanoceramics of Pr‐doped lanthanum hafnate, La2Hf2O7:Pr, were prepared by means of a high‐pressure sintering technique using nanopowders made by Pechini method. Structure, morphology, and spectroscopic properties of the ceramics compared to the starting powder are presented and discussed. Emission and excitation spectra recorded at room temperature as well as at 7 K using synchrotron radiation are presented together with results of luminescence kinetics measurements. In ceramics, at 7 K, the Pr3+ luminescence from 3P0 (blue‐green, green, and red region) and 1D2 (red) levels is accompanied by a broad‐band emission located in the 380–530 nm range of wavelengths, whereas powders gives only the Pr3+‐related luminescence. Depending on the excitation wavelength, the broad‐band emission maximum moves between 430 and 470 nm indicating superposition of at least two components. In sintered nanoceramics, the lifetimes of Pr3+ emissions from 3P0 and 1D2 levels were by 10%–20% shorter compared to the powder. The existence of different luminescence centers was proved by the selective emission decays examination. The fast 5d → 4f luminescence of Pr3+ was not observed from either of the two types of La2Hf2O7:Pr materials.