Structure and Magnetic Properties of Mn_xZn_(1-x)Cu_(0.2)Fe_(1.8)O_4 Ferrite Nanoparticles Synthesized by Sol-Gel Auto-combustion

Mn_xZn_(1-x)Cu_(0.2)Fe_(1.8)O_4(x=0.5,0.6,0.7,0.8,0.9)nanoparticles with spinel structure were synthesized by sol-gel auto-combustion method and annealed at 500℃for 4h in air in order to study the structure and magnetic properties of Mn-Zn-Cu ferrite nanoparticles.The analysis of X-ray dif- fraction(XRD)shows that all samples are single-phase spinel structure.The particle sizes of samples with different Mn content are estimated from the X-ray spectra to be 30-40nm.X-ray photoelectron spectroscopy(XPS)shows that most of Mn exist in Mn~(3+)state before and after annealing,and Fe exist in Fe~(3+/2+)mixed states before annealing and in Fe~(3+)state after annealing.The annealing leads to the increase of percentages of Mn and Fe in surface layer.The results of vibrating sample magnetometer (VSM)indicate that the coercivities(H_c)of samples annealed at 500℃steeply increase with increasing Mn content.The saturation magnetizations(M_s)of unannealed samples with increasing Mn content increase first and then decrease,and the samples(x=0.8)have maximal saturation magnetizations(M_s). The influence of annealing on the samples with different Mn content is different.