Magnetic properties of Mn doped CuO Nanoparticles

Abstract

Mn doped CuO nanoparticles, with CUO.9MnO.10 and CUI _xMnxO for 0.005 :::: x :::: 0.20 were synthesized by co-precipitation method. The conditions for the co-precipitation method were first optimized. These nanoparticles were characterized by using techniques such as X-ray powder diffraction, AC Susceptometer, Vibrating sample magnetometer and Physical properties measuring system. Powder X-ray diffraction reveals that all the samples crystallize into monoclinic-type structure. For CU09MnO.1 0 , the average particle size increases from 28 to 33 nm as the annealing temperature increases from 650 DC to 900°C. X-ray analysis reveals the presence of a secondary phase CuMn204, whose amolmt increases with the increase in temperature. Ferromagnetic behaviour was observed for these samples with a transition temperature at 80K. The manganese oxidizing state is Mn3 + for CuMn20 4 and Mn2+ for CUI-xM11xO. Also magnetic properties have been observed in CuO doped with 0.005-0.20 at. % of Mn. The transition from felTomagnetic phase to paramagnetic phase occulTed at Te = 80K regardless of the Mn concentration. Samples are single phased Up to 6% Mn concentration. For higher concentrations a secondary phase CuMn204 is observed. The unit cell volume expands with increasing Mn concentration for the low doped samples and it ceases to increase when x ~ 0.06. The existences of felTomagnetism for lower than 6% confirms the intrinsic nature of felTomagnetism. The origin of felTomagnetism is analyzed in the context of competitions among several interactions in this system.