Synthesis and evolution of magnetic properties of Ni doped La2/3Sr1/3Mn1-xNixO3 nanoparticles

摘要

A systematic investigation of the structural and magnetic properties of La2/3Sr1/3Mn1-xNixO3 (x = 0%, 5%, 15%, and 25%) perovskite nanoparticles synthesized using mild sol-gel technique is reported. These samples were characterized using x-ray diffraction (XRD), transmission electron microscopy, Fourier transform infrared (FTIR) spectroscopy, and temperature dependent magnetoresistance (MR) measurements. XRD analysis confirmed the single phase nature of the samples, and crystallite size was found to decrease from 21.4 nm to 17.0 nm with the increase in Ni concentration. Further, maximum MR was observed for 25% Ni doped sample at low temperature (77 K), whereas at room temperature (300 K) MR decreases with increase in Ni concentration. FTIR spectra show a broad peak at 605.28 cm-1, giving an evidence for the formation of metal oxygen bond which subsequently organize into a MnO6 octahedral structure as evidenced by the appearance of a well defined spectral band. Room temperature magnetization for all samples reduces with Ni doping and it is highest for 5% doped sample. The results have been explained on the basis of destruction of the partial double-exchange interactions and the exchange couplings between Mn and doped ions.