Controlled synthesis of praseodymium oxide nanoparticles obtained by combustion route: Effect of calcination temperature and fuel to oxidizer ratio

Abstract

This investigation focuses on the employment of the solution combustion route for synthesis of praseodymium oxide nanoparticles. The fabrication was be carried out by using the solution combustion of a fuel (urea) and oxidizer (praseodymium nitrate) mixture. The influence of fuel/oxidizer ratio and the temperature of calcination on the phases formed, morphological changes and the crystallite size of Pr6O11 have been checked. Various characterization tools have been used for the identification of the thermal behaviour of the precursors, structure and morphology of the prepared Pr6O11 nanoparticles, which include TGA-DTA, XRD, FT-IR, XPS, SEM, and TEM. With respect to the effect of the fuel content, it was found that using F/O ratio ≥4.0 at 500 °C praseodymium carbonate starts to form at the expense of the oxide phase. These phase changes were, also, companied by a noticeable morphological modifications. On the other hand, it was shown that Pr6O11 can be obtained as a single phase upon calcining at temperatures ≥500 °C. The electrical conductivity of Pr6O11 nanoparticles synthesized at 400–700 °C has been investigated over a measuring temperature range of 200–400 °C. The obtained results have led to a better understanding of the factors influencing the electrical conductivity behaviour of Pr6O11 nanoparticles, viz. the availability of Pr3+/Pr4+ pairs and the crystallite size.