Nickelate with general formula La_2-xSr_xNiO₄ (x≈0.33) were synthesized by the sol–gel method. Then by changing the sintering temperature and growth parameters, particles with various sizes were produced. The crystal structure and physical properties of the prepared samples were investigated by X-ray diffraction (XRD), Fourier transform IR spectroscopy (FTIR), Energy dispersive X-ray spectroscopy (EDX) and field emission scanning electron microscopy (FE-SEM) and resistivity measurements from room temperature to low temperatures. The XRD results and investigation of the surface morphology show the lowest temperature to get a single phase tetragonal structure is 920°C. These data confirm the formation of single phase structure in samples sintered at higher temperatures. The particle size increases with increase in sintering temperature. The FE-SEM results show that the particles sizes are in range of 50nm to 2mm. The results of resistivity measurements versus temperature by fourprobe method indicate that the charge ordering transition temperature move to lower temperature with decrease in particle size. 

Keywords: Nickelate, sol-gel, charge ordering, electrical property

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