In-situ synthesis of novel Co2FeO4 needle-like phases for structural and functional integration

Abstract

In this study, we proposed a new method to prepare yttrium iron garnet/yttrium iron garnet (YIG/YIG) functional joint via in-situ synthesis of novel Co 2 FeO 4 needle-like phases. It is found that the formation of the Co 2 FeO 4 needle-like phases was controlled by “two-step heterogeneous nucleation”: (i) CoO nanoparticles acted as the preliminary heterogeneous nucleation particle, reacting with O 2 to form Co 3 O 4 phase; (ii) The surface of Co 3 O 4 phase acted as the subsequent heterogeneous nucleation interface, atoms stacked along the (220) crystal plane of Co 3 O 4 to form Co 2 FeO 4 phase. Fe 3+ diffused into the glass matrix which is rich in O 2− , participating in the reaction with Co 3 O 4 and CoO. The Co 2 FeO 4 nuclei grew into needle-like phases along the [001] orientation. The Co 2 FeO 4 needle-like phases exhibited favourable mechanical property and magnetism according to the nanoindentation and magnetic force microscopy (MFM) analysis. And the shear strength of YIG/YIG joint reinforced by Co 2 FeO 4 needle-like phases could reach 72 MPa. The investigation supplies a new synthetic idea of Co 2 FeO 4 magnetic needle-like phases, which has significant application potential for the structural and functional integration in electromagnetic field.