Cooperation effect of indium and vanadium co-doped into bismuth-iron garnets on magnetic properties

Abstract

For achieving tunable saturation magnetization and line width, different cations were doped into the YIG-based garnets, which the standard molecular formula could be expressed as A3[Fe2−xMx](Fe3−yNy)O12. Most researchers have reported a single rule of one element doping (x or y) on its magnetic properties. However, the cooperation effect of x + y to the magnetic contribution was not clearly clarified. In this work, multi-doped bismuth-iron garnets {Bi0.84Ca2.16}[Fe2−xInx](Fe3−yVy)O12 (x = 0.72–0.14 and y = 1.24–1.38) with low saturation magnetizations (4πM s = 200–600 Gs at 298 K) were prepared by a conventional fluxing agent method. The cooperation effect of In3+ and V5+ co-doped into bismuth-iron garnets (BIG) on their structures and magnetic properties were systematically investigated using XPS, TEM and VSM. It could be found that the total doped concentration (x + y) was decreasing regardless of the increasing V concentration (y) and decreasing In concentration (x). As-synthesized BIG presented a well single-crystal structure, and the lattice spacing was decreasing with the decrease of x + y in accompanying with the transition of dislocations from point defects to edge dislocations. Both linear increase of Curie temperature and 4πM s with the decrease of x + y was revealed. The mechanism could be attributed that the doped non-magnetic ions could reduce the average nearest-neighbor coordination irons for oxygen ions and weaken the anti-ferromagnetic super-exchange interactions among the magnetic ions within the structure, namely dilution effect. By comparison, the total concentraions were higher than that of previous works, which the tailorable 4πM s of ferrite was not reported. Here we revealed the controllable 4πM s with higher total concentrations (x + y ≥ 1.52). These findings will be provided more opportunities for applications in microwave devices.