Synthesis and characterization of (La1-xMx)2Mo2O9-δ ; M=Ca2+, Sr2+ or Ba2+

The system (La1-xCax)2Mo2O9-δ was characterized in the region x=0.01⩽x⩽0.15 by slow-scan powder X-ray diffraction measurements in order to determine the solubility limit of CaO. For the sake of comparison, the same was repeated for (La1-xMx)2Mo2O9-δ where M=Sr2+ or Ba2+ and x=0.05 and 0.10, respectively. In addition, the electrical conductivities of some of the typical compositions investigated in the present study were measured as a function of temperature by means of the ac impedance technique. The suppression of the phase transition in La2Mo2O9 by the alkaline-earth dopants was verified by differential thermal analysis of the samples.