Synthesis and magnetic properties of Y_3-xDy_xFe₅O₁₂ nanoparticles

Dy³⁺-substituted garnet nanoparticles Y_3-xDy_xFe₅O₁₂ (x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0) were fabricated by a sol-gel method and their crystalline structures and magnetic properties were investigated by using X-ray diffraction (XRD), infrared spectroscopy and vibrating sample magnetometer (VSM). The XRD patterns of Y_3-xDy_xFe₅O₁₂ have only peaks of the garnet structure and the sizes of particles range from 37 to 63 nm. Results of VSM show that the saturation magnetization of Y_3-xDy_xFe₅O₁₂ (0 < x ≤ 1) particles is not only obviously less than pure Yttrium iron garnet, but also decreases with increasing the Dy concentration (x) in a linear manner. Meanwhile, it is observed that with the enhancement of the surface spin effects, the saturation magnetization rises as the particle size is increased.