A series of layered CuCr_1-xMg_xO₂ (0 ≤ x ≤ 0.08) polycrystalline ceramics were prepared. The effects of substituting Mg²⁺ cations for Cr³⁺ cations on the grain composition, grain size, grain quantity, and electrical conductivity were investigated. When x = 0–0.04, the distinct layered structure grain grew rapidly with the increase of magnesium in the composition, and the average grain size increased from 2.5 μm (x = 0) to 15 μm (x = 0.04) due to the decrease of activation energy. Furthermore, the bulk density and lattice constant also reached the maximum and minimum values of 4.367 g/cm³ and 17.083 respectively at x = 0.04. When x = 0.05–0.08, the average grain size slightly decreased due to the grown-up second-phase MgCr₂O₄ hindering of grain growth. The results showed that the average size of the second-phase MgCr₂O₄ had reached 1.3 μm when x = 0.04. In general, the larger the grain size of polycrystalline ceramics, the more defects in the grain boundaries, and the better its electrical conductivity. Therefore, the solid-phase reaction, which can obtain larger grain size and more grain boundary defects, was chosen here to prepare CuCr_1-xMg_xO₂ polycrystalline ceramics, so as to obtain a highly conductive CuCr_1-xMg_xO₂ ceramic material. The minimum resistivity of the obtained CuCr_0.6Mg_0.4O₂ polycrystalline ceramic is only 0.091 Ω·cm, which is of great significance for the development of transparent conductive oxides

Keywords: CuCr_1-xMg_xO₂ grain composition grain size grain quantity electrical conductivity