Magnetic Properties of Y3−2xCa2xFe5−xVxO12 Garnets

A comprehensive study of the magnetic properties of Y3−2xCa2xFe5−xVxO12 (0 ≤ x ≤ 1) has been performed. The garnet ferrites samples were prepared by the ceramic technique, and X-ray diffraction analysis indicates the formation of single cubic phase. Vibrating sample magnetometry (VSM) and a superconducting quantum-interference device (SQUID) were used to measure the magnetic properties, especially the magnetization and thermo-magnetic behavior. The magnetization curves exhibit the typical characteristics of ferrimagnetic materials at both 4.2 K and at room temperature. The samples have a low coercivities (between 20 and 40 Oe) and saturation magnetizations as high as 36 emu/g at 4.2 K. The saturation magnetization decreases with V and Ca contents, reaching about 8 emu/g at 4.2 K (x = 1). For all samples, the saturation magnetization decreases with increasing temperature, whereas the Curie temperature increases for small values of x, from 557 K for x = 0 to a maximum of 590 K for x = 0.2. For larger values of x, it decreases and reaches 525 K for x = 1.0. The basic experimental trends reflect the occupancy of the tetrahedral 24d sites by vanadium in combination with the predominant intersublattice exchange constant Jad, although the nonzero magnetization at x = 1.0 indicates that about 10% of the substituted V atoms goes onto the octahedral 16a sites.