Phase Evolution, Microstructure, and Electrical Resistivity of CaMnO3-CaZrO3 Composites

The phase evolution, microstructure, and electrical resistivity of (1-x) CaMnO3-(x) CaZrO3 composites were investigated. A mixture of the CaMnO3-type and CaZrO3-type phases with an orthorhombic structure was formed with the compositions of x = 0.25, 0.5, and 0.75. The diffraction peaks of the CaZrO3-type phase and those of the CaMnO3-type one were shifted toward the higher angle and the lower one, respectively, indicating that the substitutional solid solution occurred mutually. All the specimens exhibited dense microstructures except the composition of x = 1.0. The value of the linear shrinkage for the compositions of x = 0.25, 0.50, and 0.75, i.e., the mixture of the CaMnO3-type and CaZrO3-type phases, is higher than that for the single phases, i.e., CaMnO3 and CaZrO3. The composition of x = 0.0, i.e., CaMnO3, showed an electrical resistivity of about 1 Ω·cm. Since CaZrO3 is an insulator, the electrical resistivity of (1-x) CaMnO3-(x) CaZrO3 composites can be controlled from about 1 Ω·cm to infinity by changing the x value.