The Sonochemical Synthesis of Mixed Oxides

In addition to the above reported synthesis of ferrites our search has revealed that aluminates [119], nickelates [120], and manganates [121], have also been prepared by the sonochemical method. Nanosized nickel aluminate spinel particles have been synthesized [119] with the aid of ultrasound radiation by a precursor approach. Sonicating an aqueous solution of nickel nitrate, aluminum nitrate, and urea yields a precursor which, on heating at 950 °C for 14 h yields nanosized N1A1204 particles with a size of ca. 13 nm and with a surface area of about 108 m g-i. 

Nanostructured LaNiOs was prepared by co-precipitation under ultrasonic radiation [120], Using various characterization methods and evaluation of catalytic activity, the effects of ultrasound on the structural properties and catalytic activity of LaNiOs were studied. The TEM showed that the ultrasound could cause a decrease in the particle size. The average particle size of LaNiOs prepared by sonochemistry is 20 nm. The specific surface area of LaNiOs is 11.27 m g h Ultrasound could lead to increased surface oxide content and surface crystal oxygen vacancies. The TPR result showed that the LaNi03 prepared by sonochemistry has a lower reduction temperature and a higher ratio of surface oxygen to crystal oxygen. The evaluation of catalytic activity showed that ultrasound could increase the catalytic activity of LaNiOs for NO decomposition. 

Lanthanum strontium manganate, known also as LSM, is known for its magnetoresistance properties, and is also used in solid oxide fuel cells (SOFC). Sonochemistry was used for its preparation [121]. Electron magnetic resonance (EMR) spectra of nanosized sonochemically sintered powders of Lao.7Sro.3Mn03 (annealed, Tc = 340 K) were studied. 

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