Structural and electromagnetic evaluations of YIG rare earth doped (Gd, Pr, Ho,Yb) nanoferrites for high frequency applications

Abstract

Multiple rare earth metal cations (Gd, Yb, Ho and Pr) were doped in yttrium iron garnet (YIG) nanocrystalline ferrites. Following five samples i.e. YIG (Y3Fe5O12), Gd doped YIG (Y2.8Gd0.2Fe5O12), Pr doped YIG (Y2.8Pr0.2Fe5O12), Ho doped YIG (Y2.8Ho0.2Fe5O12) and Yb doped YIG (Y2.8Yb0.2Fe5O12) were prepared using sol-gel auto-combustion synthesis route. The samples were characterized via XRD, FTIR, SEM and VSM whereas VNA was also used to evaluate these samples for high frequency applications. XRD analysis confirms the peaks of garnet ferrites which show cubic phase structure for all YIG doped samples. The lattice constant in all the substituted garnet nanoferrites initially increased and then consequently decreased as the doping increased except for Pr-substituted YIG nanoferrites. This is due to the greater ionic radii of Pr as compared to other doped YIG nanoferrites. FTIR was used to find out the garnet phase in all the substituted YIG nanoferrites. The morphological features of the garnet nanoferrites were observed using the SEM images. High frequency measurements such as permittivity, permeability, dielectric losses, ac conductivity, electric modulus and Q factor of YIG and doped YIG nanoferrites were measured using VNA. Saturation magnetization, remanence, coercivity, squareness ratio, Bohr magneton and magneto crystalline anisotropy were measured from the magnetic hysteresis loops recorded by VSM. Pr-doped YIG show better dielectric and magnetic properties with lower losses at higher frequency suggest the use of these garnet nanoferrites for microwave high frequency devices and applications.