Microstructure and electrical properties of Ca1−x Er x MnO3−δ powders prepared by hydrothermal technique

In order to decrease the resistivity of the CaMnO3 powders for obtaining an excellent conductive material, we have prepared the Ca1−x Er x MnO3−δ (0.30 ≤ x ≤ 0.75) powders through the hydrothermal technique, the effects of Er content, reaction time, and the type of solvent on the structure, morphology, and electrical properties of the Ca1−x Er x MnO3−δ powders have been also studied. The resistivity of the Ca1−x Er x MnO3−δ powders reached the lowest value of 1.290 kΩ m when x = 0.3, with deionized water as solvent, and reaction time of 15 days. The XRD patterns showed that all the Ca1−x Er x MnO3−δ powders owned well-crystallized perovskite structure, which illustrated that the Ca1−x Er x MnO3−δ powders with Er content that was pretty small, especially the Ca0.70Er0.30MnO3−δ powders, can be successfully synthesized through the hydrothermal technique. The SEM pictures showed that the Ca1−x Er x MnO3−δ powders changed from acicular structure to the lamellar structure with increase in Er content, and the resistivity of the Ca1−x Er x MnO3−δ powders with acicular structure was much lower than that of lamellar structure, which proved that the microstructure is the internal factor for improving the electrical properties.