Synthesis, crystal structure, and magnetic properties of Ni[formula omitted]CrBO[formula omitted].

Ni 2 CrBO 5 has been synthesized and investigated by X-ray diffraction, dc magnetization, and specific heat measurements. The unusual cation distribution has been established: the M1 and M3 sites are occupied by Ni 2 + ions, the M2 site is by Cr3＋ ions, and the M4 site is mixed, featuring both Ni 2 + and Cr3＋ ions. The magnetic order onsets at T N = 140 K, which is confirmed by a λ -type peak in specific heat, followed by the dome-shaped anomaly of the magnetization at about 30 K. In the magnetically ordered state, a remarkable sequence of temperature-induced magnetization reversal sensitive to the measurement's regime is observed. Dominant antiferromagnetic interactions are characterized by the Weiss temperature θ = −73 K. The effective magnetic moment of 5.37 μ B per formula unit is close to the spin-only one. The effect of the cation distribution on the magnetic properties is discussed. • Phase-pure Ni 2 CrBO 5 with a ludwigithe structure was obtained using a solid-state reaction in two stages. • The compound has morphology in the form of elongated bars and needles. • Powder X-ray diffraction study has shown an orthorhombic crystal structure and unusual distribution of Ni 2 + and Cr 3 + ions over symmetry inequivalent metal sites. • The magnetization and specific heat measurements have revealed the compound undergoes magnetic phase transition at T N =140 K. [ABSTRACT FROM AUTHOR]