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Schlagwörter:
Cobalt; Cobalt metallography; Crystal structure; Electromagnetic wave emission; Emission spectroscopy; Ground state; Hydraulic structures; Multiferroics; Spin dynamics; X ray absorption spectroscopy; X ray scattering; X rays, Ambient pressures; Co-spin state transition; Crystal structure analysis; Intermediate spins; Soft x-ray absorption spectroscopies; Spin state transition; State transitions; X-ray emission spectra, Bismuth compounds
Zusammenfassung:
Confusion has arisen about the Co spin-state transition under high pressure for multiferroic BiCoO3. The crystal structure analysis indicates a high-spin (HS) to low-spin (LS) state transition with increasing pressure, while Co Kβ X-ray emission spectra present a high-spin to intermediate-spin (IS) state transition. Herein, the spin state of Co3+ in BiCoO3 is investigated utilizing soft X-ray absorption spectroscopy (XAS) at the Co-L2,3 and O-K edges at room temperature under ambient pressure. Furthermore, the spin state transition of Co3+ under high pressure is investigated by Co Kβ X-ray emission spectra. A pure HS-Co3+ ground state is found in the BiCoO3 sample prepared from the precursor and oxidizer mixed method—and the existence of a small part of LS-Co3+ in the BiCoO3 sample prepared from the precursor and oxidizer sandwiched method. A complete HS-Co3+ to LS-Co3+ transition is observed under high pressure up to 32.3 GPa. The results clarify the debate on the spin-state transition of BiCoO3 under high pressure and will deepen our understanding of the intrinsic physical properties on it. © 2021 Wiley-VCH GmbH
