Comparison of the Crystalline Structure and Magnetic Properties in Coprecipitated CoFe_2O_4 and CoLa_(0.1)Fe_(1.9)O_4

摘要

Comparison of the crystalline structure and magnetic properties in CoFe_2O_4 and CoLa_(0.1)Fe_(1.9)O_4 nanoparticles have been studied. The obtained samples are characterized by using X-Ray Diffractometer (XRD), Fourier Transform InfraRed (FTIR) and Vibrating Sample Magnetometer (VSM). The XRD results show that the crystallite size of the samples are 24.539 nm and 28.772 nm for the CoFe_2O_4 and CoLa_(0.1)Fe_(1.9)O_4 nano particles, respectively. Furthermore, the crystalline strain is 0.00460 and lightly decreases to 0.00392 with the presence of lanthanum. The different of the atomic radius for both Fe3+ (1.26 ?) and La~(3+) (1.87 ?) should attribute to the change of the crystalline strain. FTIR results show that the absorption peak of the CoFe_2O_4 occur at k = 591.21/cm and the CoLa_(0.1)Fe_(1.9)O_4 is 594.10/cm. This indicate that the lanthanum cation successfully substitutes to the original bonding-structure of the CoFe_2O_4. VSM results show that the Hc are 1.02 kOe and 0.705 kOe for the samples without and with La~(3+) cations. Moreover, the Ms is equal 69.625 emu/g and decrease of 55.70 emu/g with the present of the La~(3+) cations. Finally, the strains-induce-magnetism should contribute to the changes of the Ms that associated with changes in crystalline strains at the previous discussion.