All compositions of La2-xSrxMo2-yWyO9-δ
(x = 0-0.2 and y = 0-0.3) were prepared via solid
state reaction, using La2O3, SrCO3, MoO3 and WO3
(≥ 99.0%, Aldrich and Kanto chemical) as starting
materials. La2O3 was calcined at 1000°C for 5 h to
remove hydroxide and carbonate before weighed.
The mixtures were ball-milled in a high density
polyethylene bottle with alumina balls as grinding
media and using ethanol as medium. After drying,
the mixtures were calcined at 950°C for 9 h in air
and held at the reaction temperatures determined
from the Simultaneous thermal analysis (STA, TA
Instruments SDT2960).