![]() The time spectra of the NFS from the 57 Fe nuclei were recorded at room temperature in the pressure range up to 50 GPa without applying an external magnetic field. To perform the NFS studies at high pressures, a 57 FeBO 3 crystal with the dimensions 80 × 40 × 10 μ m 3 was placed into a high-pressure cell with diamond anvils. The thickness of the plates was 10–40 μ m, and the maximum area of a plate was 8 × 8 mm 2. The crystals had the form of plates whose large surfaces were parallel to the (111) basal plane. They contained iron enriched with the 57 Fe isotope to 96%. Seleznev at the Simferopol’ State University. High-quality transparent FeBO 3 crystals light green in color were grown from flux by V.N. The measurements were performed at the ID18/ID22N Nuclear Resonance beamlines of the European Synchrotron Radiation Facility (ESRF, Grenoble, France). In this paper, we study a FeBO 3 single crystal under high pressure by the nuclear forward scattering (NFS) method, which is a version of Mössbauer spectroscopy on the time scale. This suggests that the value of angle φ is constant within the above-mentioned temperature interval. It was found from NMR measurements that, in the interval 4.2 K < T < T N, the magnetic moments of the sublattices and the weak ferromagnetic moment show identical temperature dependences. The angle φ between them is ~0.9 °, and the resulting weak ferromagnetic moment also lies in the basal plane. At normal pressure and room temperature, the magnetic moments of two iron ion sublattices lie in the (111) basal plane and are almost antiparallel. Thus, the environment formed by six oxygen ions around iron is almost cubic. The magnetic Fe 3+ ions are in an octahedral environment formed by oxygen ions with (Fe–O) interion distances of 2.028 Å, (Fe–Fe) distances of 3.601 Å, and (O–Fe–O) bond angles of 91.82 ° and 88.18 °. borate FeBO 3 has a calcite rhombohedral structure, belongs to the R 3 c ( D 6 3 d ) space group, and is an antiferromagnet with a weak ferromagnetism and Néel point T N = 348 K. The time-domain NMR method proved to be useful to study the effect of B in the corrosion of other metals or other corrosive liquid media when the reactions produce or consume paramagnetic ions. The protective effect of B was explained by magnetic forces that maintain the Cu 2+ in the solution/metal interface for a longer time, hindering the arrival of the new corrosive agents, and leading to the formation of a CuCl phase, which may contribute to the rougher surface. Atomic force microscopy and X-ray diffraction results of the analysis of the corroded surfaces reveal a detectable CuCl phase and an altered morphology when B is present. The results show that the magnetic field ( B = 0.23 T) of the time-domain NMR instrument reduces the corrosion rate by almost 50%, in comparison to when the corrosion reaction is performed in the absence of B. The corrosion product, Cu 2+, is a paramagnetic ion and its concentration in the solution was determined in real time in the corrosion cell by time-domain NMR relaxometry. Here we evaluated the effect of a magnetic field ( B) on the corrosion of copper in aqueous HCl solution under open circuit potential. The corrosion of metals is a major problem of modern societies, demanding new technologies and studies to understand and minimize it.
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