Double Peak Behavior of Resistivity-Temperature Curves in (Nd / Pr)0.67Sr0.33MnO3 Manganites

摘要

We have reported the synthesis of polycrystalline samples of R0.67Sr0.33MnO3 (R  Pr, Nd) from the precursorsudof PrMnO3, NdMnO3 and SrMnO3 by using solid state reaction method. These samples were sinteredudat 1200 °C and 1400 °C. Some of samples were also undergone oxygen annealing at 950 °C for 6 h. Alludthe synthesized samples were characterized by X-Ray diffraction (XRD) technique, scanning electron microscopyud(SEM) and low temperature resistivity versus temperature (R-T) measurement. The XRD patternsudshow the monophasic nature of the sintered and annealed samples. The sintered samples ofudNd0.67Sr0.33MnO3 has metal- insulator transition at 250 K, while the sample annealed in oxygen shows twoudpeaks, one sharp peak at 250 K and other broad peak at 200 K. The sintered samples of Pr0.67Sr0.33MnO3udhas only one peak at 290 K, while the sample annealed in oxygen shows two peaks, one sharp peak at 290udK and another broad peak at 225 K. The two peak behavior in the annealed samples has been explained byudinhomogeneous diffusion of oxygen in the core of the grain and at the grain boundaries regionWhen you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35965