ULTRASOUND EFFECTS ON CERIUM, PRASEODYMIUM, AND TERBIUM OXIDES

The behavior of intermediate higher rare earth oxides, such as Pr6O11 and Tb4O7, and Ce1-xPrxO2 compounds as powders has been studied by a n ew experimental procedure. They have been subjected to ultrasound irra diation (20 kHz) during immersion in a 5% dilute acetic acid solution. Pure PrO2 and TbO2 oxides (yield 100%) can be formed within sonicatio n periods of 7-8 and 15-24 hr, respectively (instead of 3 days and 1 m onth through classical methods). Electron microscopic images and granu lometry measurements show that the grain size has decreased greatly af ter sonication. The results are discussed in terms of cavitation pheno mena and Of chemical species (H-2, 02, HO2, OH, H2O2, ... ) forMed dur ing sonolysis of water and acetic acid. (C) im Academic Press, Inc.