Synthesis of nanostructured perovskite powders via simple carbonate co-precipitation

A very simple, cost-effective, chloride- and alkali-free, carbonate co-precipitation synthesis in aqueous medium was applied in the preparation of perovskite-type lanthanum manganese oxide-based powders, i.e. La0.70Sr0.30MnO3−δ (LSM) and La0.75Sr0.25Cr0.5Mn0.5O3−δ (LSCrM). The precursors so obtained yielded nano-structured perovskite oxides when treated at 900°C and 800°C, respectively. The measured BET surface areas were in the low-end range for high temperature oxides (4 m2 g−1 and 10 m2 g−1) but the X-ray crystallite size was as low as 50 nm for LSCrM and 90 nm for LSM.

Effect of La2O3 Addition on the Microstructure and Electrical Properties of Copper-Nickel Manganese Thermistors

The effect of La2O3 addition on the microstructure and electrical properties of Mn0.75Ni1.25CuO4-xLa2O3 (0≤x≤0.3) was studied. The crystal structure, phase compositions and morphology were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The sintered ceramic bodies was typical polycrystalline, with cubic spinel structure of copper manganese oxide, rocksalt structure of nickel copper oxide, along with monoclinic phase of copper oxide and orthorhombic perovskite structure of lanthanum manganese oxide. The obtained ρ77K, B77K/90K constant and activation energy of the thermistors were in the range of 3.88-9.29 Ω cm, 245-261 K, and 0.0211–0.0225 eV, respectively. This means that the electrical properties can be adjusted to desired values, depending on the La content. So these prepared thermistors were intended to be used under low temperature conditions.