Substitution effect of Ni2+ on the magnetism and electrical properties of Ca3CoMnO6 compound

Abstract

A series of Ni2+ doped Ca3Co1-xNixMnO6 (0 ≤ x ≤ 0.15) samples were prepared for this study. Their structure, magnetism and electrical properties were investigated. The results show that the spin of Ni2+ is antiferromagnetically coupled to the neighbor Mn4+ cations. In Ni2+ substituted samples, the short-range magnetic correlation is inhibited and the long-range antiferromagnetic structure is strengthened. Due to the random distribution of Ni2+ substitution in Co2+ sites, the macroscopical ferroelectric domains of Ca3CoMnO6 are destroyed and more polar nanoregions form. With the increase of Ni2+ content, the relaxor behavior of the ferroelectric transition becomes stronger and the activation energy Ea decreases monotonously. The enhanced antiferromagnetic interaction also reinforces the dipole correlation, leading to the increased static freezing temperature Tf in Ni2+ doped samples. Magnetodielectric coupling is significantly improved due to the magnetic structural variation produced by doping of compound with Ni2+ cations. For the x = 0 sample, the maximal deviation of the dielectric permittivity at H = 7 T relative to the value at H = 0 is about 2.25 %. While for the x = 0.1 and 0.15 samples, this value is 7.5 % at H = 7 T.