The Mn3Sb metastable compound is formed at high pressure and temperature and it decomposes upon heating above 420 K into Mn2Sb and Mn. It has a cubic crystalline structure describing the Pm-3m (№ 221) space group with a lattice parameter of a = 0.400 nm. In the present work, according to the results of neutron diffraction investigations and taking into account magnetometry data, it is shown that Mn3Sb is an antiferromagnet, and a model of the magnetic structure with a triangular configuration of equal magnetic moments in magnitude is proposed. The magnetic moments of manganese atoms, constituting the basis of a unit magnetic cell, lie in the (111) plane and form an equilateral triangle. According to neutron diffraction data, the magnetic moments of manganese atoms were determined at different temperatures.
Indium-substituted strontium hexaferrites were prepared by the conventional solid-phase reaction method. Neutron diffraction patterns were obtained at room temperature and analyzed using the Rietveld methods. A linear dependence of the unit cell parameters is found. In3+ cations are located mainly in octahedral positions of 4fVI and 12 k. The average crystallite size varies within 0.84-0.65 μm. With increasing substitution, the TC Curie temperature decreases monotonically down to ~ 520 K. ZFC and FC measurements showed a frustrated state. Upon substitution, the average and maximum sizes of ferrimagnetic clusters change in the opposite direction. The Mr remanent magnetization decreases down to ~ 20.2 emu/g at room temperature. The Ms spontaneous magnetization and the keff effective magnetocrystalline anisotropy constant are determined. With increasing substitution, the maximum of the ε/ real part of permittivity decreases in magnitude from ~ 3.3 to ~ 1.9 and shifts towards low frequencies from ~ 45.5 GHz to ~ 37.4 GHz. The maximum of the tg(α) dielectric loss tangent decreases from ~ 1.0 to ~ 0.7 and shifts towards low frequencies from ~ 40.6 GHz to ~ 37.3 GHz. The low-frequency maximum of the μ/ real part of permeability decreases from ~ 1.8 to ~ 0.9 and slightly shifts towards high frequencies up to ~ 34.7 GHz. The maximum of the tg(δ) magnetic loss tangent decreases from ~ 0.7 to ~ 0.5 and shifts slightly towards low frequencies from ~ 40.5 GHz to ~ 37.7 GHz. The discussion of microwave properties is based on the saturation magnetization, natural ferromagnetic resonance and dielectric polarization types. ; Investigations were performed under financial support from the Russian Science Foundation (Agreement No. 19-19-00694 of 06 May 2019). ; With funding from the Spanish government through the 'Severo Ochoa Centre of Excellence' accreditation (CEX2019-000917-S). ; Peer reviewed