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The structural and magnetic properties of Cr 2 O 3 have been studied by means of X-ray and neutron powder diffraction at high pressures up to 35 GPa. The lattice compression of the rhombohedral crystal structure of R 3 ¯ c symmetry is slightly anisotropic with anomaly in the pressure behavior of the c/a parameters ratio at P ≈ 20 GPa of presumably magnetic nature. The oxygen octahedra around chromium ions become more symmetric with close values of shared and unshared bonds under high pressure. The antiferromagnetic structure of Cr 2 O 3 remains stable in the studied pressure range up to 35 GPa. The pressure coefficient of the Néel temperature, (1/ T N )( dT N /dP ) = + 0.0091 GPa −1 , is significantly less in comparison with perovskite-like compounds containing Cr 3+ and Mn 4+ ions of similar electronic configuration. [ABSTRACT FROM AUTHOR]

Fe-Si based alloys have been widely studied because of the excellent high frequency, soft magnetic properties, which are determined by the hyperfine structure of alloys. The evolution of the hyperfine structure and magnetic characteristics in an Fe-Si-Cr alloy with increasing heat treatment temperature have been studied. Fe-21.5 at.% Si-2 at.% Cr alloy powder was prepared and observed. The Fe-Si based alloys have three-step phase transitions under heat treatment. Hyperfine magnetic fields are increased after A2 ordered as the localized degree of 3d electrons decreased. Quadrupole splitting in alloys mostly originate from the paramagnetic phase, and the asymmetry of charge could increase the polarization response under high frequency microwaves. This could increase the microwave permittivity and paramagnetic phase ratio, which can contribute to better soft magnetic properties. The Mössbauer effective thickness of a Fe-Si-Cr alloy particles sample is calculated as 7.3345. Theoretical magnetic moments from first principle calculations and the Mössbauer result can be obtained and are consistent with experiment results. The formation of the DO3 phase could deteriorate soft magnetic properties of samples. High permeability of Fe-Si-Cr alloys can be obtained under heat treatment of the critical temperature when the DO3 phase starts to form. [ABSTRACT FROM AUTHOR]

In this work, some relations between crystal structure and magnetic ordering in CrCoFeNiAl HEAs are discussed in view of the KKR-CPA calculations. Remarkably, it is noticed that the transition between fcc and bcc phases in the analysed CrCoFeNixAl and CrCoFeNiAlx alloys is closely related to change in ordering of the local magnetic moments, namely the magnetic moment on Cr is either parallel (ferromagnetic) or antiparallel (ferrimagnetic) to the magnetic moments of other atoms (Co, Fe and Ni). On the whole, the theoretical diagram showing the fcc-bcc phase preference and their coexistence vs. alloy composition well corroborates with available experimental data. [ABSTRACT FROM AUTHOR]