Impact of In³⁺ cations on structure and electromagnetic state of M−type hexaferrites

The solid solutions of In3+ doped M−type strontium hexaferrites were produced using a conventional solid-state reaction method, and Rietveld analysis of the neutron diffraction patterns was conducted. In3+ cations occupy octahedral (4fVI and 12 k) and tetrahedral (4fIV) positions (SG = P63/mmc (No. 194)). The average particle size is 837–650 nm. Curie tempearature (TC) of the compounds monotonically decreased down to ∼ 520 K with increasing x. A frustrated magnetic state was detected from ZFC and FC magnetizations. saturation magnetization (Ms) and effective magnetocrystalline anisotropy coefficient (keff) were determined using the law of approach to saturation. A real permittivity (ε/) maximum of ∼ 3.3 at ∼ 45.5 GHz and an imaginary permittivity (ε//) of ∼ 1.6 at ∼ 42.3 GHz were observed for x = 0.1. A real permeability (μ/) maximum of ∼ 1.5 at ∼ 36.2 GHz was observed for x = 0. A μ// imaginary permeability maximum of ∼ 0.8 at ∼ 38.3 GHz was observed for x = 0.1. The interpretation of the results is based on the type of dielectric polarization and the natural ferromagnetic resonance features.