Tailoring the structural, conductivity, and magnetic properties of La2Ni1−xCrxMnO6 double perovskites by B-site Cr substitution

Abstract

Double perovskite ceramics, La₂Ni_1−xCr_xMnO₆; (x = 0.2, 0.5, 0.8, 1.0) were developed using the sol–gel method. X-ray diffraction (XRD) and Rietveld refinement revealed the presence of rhombohedral and orthorhombic phases in addition to the main monoclinic structure, indicating the existence of disorder within the samples. The degree of disorder decreased with increasing chromium (Cr) substitution, with pure La₂CrMnO₆ exhibiting the highest order (approximately 99.70%). DC conductivity (σ_dc) and magnetization strongly depend on the degree of antisite disorder. The sample with x = 0.2 composition attained the highest DC conductivity (σ_dc = 8.023 × 10^–2 S/m) and saturation magnetization (M_s = 51.89 emu/g). M_s showed a decreasing trend upon increasing Cr substitution. The observed hysteresis loops at ± 60 kOe revealed antiferromagnetic interactions in addition to the primary ferromagnetic phase. Various possible mechanisms were discussed in detail to understand the impact of Cr substitution on the structure, electrical conductivity, and magnetic properties in La₂Ni_1−xCr_xMnO₆ double perovskite compounds.