Thermal decomposition of freeze-dried complex oxalate precursors allow
s the synthesis of crystalline phases in the FeNbO4-TiO2 system at rel
atively low temperature. This system shows not only a rutile type, but
also a wolframite-type solid solution (ss), which exists at lower tem
peratures. The temperature of the reversible transformation wolframite
-rutile decreases with increasing TiO2 content.