Electronic and magnetic properties of boron substituted CuFeO₂ delafossite oxide

ABSTRACT

Synchrotron x-ray diffraction (SR-XRD) and X-ray absorption fine structure spectroscopy (XAFS) were used to investigate the crystal and electronic properties of boron-substituted CuFeO₂ material at room temperature. Without boron substitution, the polycrystalline structures of the trigonal (rhombohedral) ‘$R\overline{3}m$’ CuFeO₂ (87.7%) and hexagonal ‘P6₃/mmc’ (12.3%), which were also present in each sample but in different proportions, were utilised to identify the base material. XRD patterns revealed that, beyond 10% boron substitution, the metal–oxygen bonds (Fe-O and Cu-O) weakened, resulting in the formation of new tetragonal ‘I4₁/amd’ CuFe₂O₄ crystals. Although the CuFeO₂ structure was preserved, it is conceivable that the presence of other crystal structures could lead to the formation of new features. This state arose as a result of CuFe₂O₄ crystallization and the impact of boron activity on the surrounding oxygen structures. By measuring magnetisation at both swept temperatures (10–300 K) and applied magnetic fields (±30 kOe), the magnetic properties of the samples were investigated. In the 10–300 K temperature range, the polycrystalline samples exhibit a ferromagnetic property without a magnetic phase transition. This suggests that replacing B with Fe in CuFe_1−xB_xO₂ does not influence the primary magnetic property of CuFeO₂. The samples’ saturation magnetisation (Ms) values gradually fall as the B substitution content increases with Fe. This is because there's a chance that the non-transition metal B in CuFe_1−xB_xO₂ will boost antiferromagnetic superexchange Cu-O interactions while lowering the p-d exchange interaction.

GRAPHICAL ABSTRACT

KEYWORDS:

• Magnetic materials
• oxides
• electronic structure
• absorption spectroscopy

Acknowledgment

XAFS (proposal no. 2022B1663) and SR-XRD (proposal no. 2022B1664) measurements were performed at the SPring-8 synchrotron facility with approval from the Japan Synchrotron Radiation Research Institute (JASRI).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This study is partly supported by the 2219 program of The Scientific and Technological Research Council of Turkey (TÜBİTAK) with Ref. No. 53325897-115.02-152809.