Structural and magnetoelectric interactions of (Ca, Mg)-doped polycrystalline multiferroic CuFeO2

• Relaxation of the rhombohedral distortion of the FeO6 octahedra.
• Ca/Mg introduced into Fe layers blurs the magnetic transitions
• Increase of the dielectric permittivity at Neel temperature TN2.

In this work, we investigate crystal structure of delafossite-type oxide CuFe1−x(Ca, Mg)xO2 (0 ≤ x ≤ 0.04). It's known to induce a distortion in the structure, there is an important variation in the two lattice parameters a and c because of the big substitution of biunique radius of Ca2+ and Mg2+ (rCa2+ = 1 Å, rMg2+ = 0.74 Å). Magnetic susceptibility measurements show a magnetic dilution for Ca-doped simples and an amplification of χ with Mg-doping. Temperature dependence of the dielectric permittivity for CuFe1−xMgxO2 present an amplification of ϵ′ at TN2 = 9.1 K

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