Synthesis of nano-crystalline Sr2MgMoO6−δ anode material by a sol–gel thermolysis method

Nano-crystalline Sr2MgMoO6−δ (SMMO) powders were synthesized successfully by a novel sol–gel thermolysis method using a unique combination of polyvinyl alcohol (PVA) and urea. The decomposition behavior of gel precursor was studied by thermogravimetric-differential thermal analysis (TG/DTA) and the results showed that the double-perovskite phase of SMMO began to form at 1000 °C. The microstructure of the samples had been investigated by X-ray diffraction (XRD), transmission electron microscope (TEM), selected area electron diffraction (SAED), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). XRD patterns confirmed that well-crystalline double-perovskite SMMO powders were obtained by calcining at 1450 °C for 12 h. TEM morphological analysis showed that SMMO powders had a mean particle size around 50–100 nm. The SAED pattern and Raman spectroscopy showed that the SMMO powders were nano-polycrystalline well-developed A(B′0.5B″0.5)O3 type perovskite material. The XPS results demonstrated that the Mo ions in SMMO had been reduced after exposure to H2. The electric property was studied by four-probe method. The results showed that conductivity was 8.64 S cm−1 in 5.0% H2/Ar at 800 °C and the activation energies at low temperatures (400–640 °C) and high temperatures (640–800 °C) are about 21.43 and 6.59 kJ mol−1, respectively.