Acoustic Emission during Leaching of Pr6O11 in Dilute Acetic Acid

In the course of the selective dissolution (leaching) of an intermediate praseodymium oxide, Pr6O11, in contact with a dilute acetic acid solution, it is possible to record an ultrasonic acoustic emission. When the chemical reaction is taking place the solid material loses Pr3+ ions to the solution and a residue of PrO2 remains. Over the course of the experiment (nearly 12 hr) various kinds of signals were recorded. The most important and intense response occurred nearly 8 hr after the beginning of the process. The acoustic emission is tentatively explained in terms of the dissolution of parts of the grains with a high amount of Pr3+ ions, and/or discohesion or breaking of inclusions.