Hyperfine characterization of metastable tetragonal configurations in Pr-doped zirconias

The PrxZr1-xO2 ceramic system obtained by coprecipitation has been investigated at zirconium sites as a function of Pr content (1, 10, and 15 mol %) and of annealing temperature by means of the perturbed angular correlations (PAC) technique. Praseodimium enters zirconia forming a tetragonal solid solution whose extent increases with Pr content. In 10 and 15 mol % Pr-doped samples, metastable tetragonal zirconia is present in its two known t- and t'-forms, the latter form being the one which involves a higher dopant concentration. While Rietveld refinement and thermal analyses indicate the uncompleted crystallization of the as-obtained powders, PAC allows the phase identification of the amorphous residues. Minor changes observed in the hyperfine interaction at high temperatures reveal the incipient ceramic degradation. Experiments indicate that, up to 15 mol % of dopant content, Pr behaves as an efficient zirconia stabilizer.