Generation of ternary Pr-Mo-O oxides by solid state reactions between oxide powders under ultrasonic stirring

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and scanning elec tron microscopy are used to prove that the ultrasound used for the preparat ion of molybdenum- and praseodymium-based heterogeneous multiphase catalyst s can induce solid-state reactions at room. temperature between the binary oxides Pr6O11 and MoO3. Turbulent flows and shock waves produced by the ult rasonic cavitation are thought to cause particles to collide into one anoth er and to generate local temperatures which are sufficiently high far induc ing interparticle melting. Unequivocal evidence is provided by ToF-SIMS tha t the ultrasonic dispersion leads to the surface formation of the praseodym ium molybdate phase Pr2Mo3O12.