title: Volatile metal beta-diketonates--new precursors for the sonochemical synthesis of nanosized materials--sonolysis of thorium(IV) beta-diketonates.
abstract: Ultrasonic irradiation (22 kHz, Ar atmosphere) of Th(IV) beta-diketonates Th(HFAA)4 and Th(DBM)4, where HFAA and DBM are hexafluoroacetylacetone and dibenzoylmethane respectively, causes them to decompose in hexadecane solutions, forming solid thorium compounds. The first-order rate constants for Th(IV) beta-diketonate degradation were found to be (9.3 +/- 0.8) x 10(-3) for Th(HFAA)4 and (3.8 +/- 0.4) x 10(-3) min-1 for Th(DBM)4, (T = 92 degrees C, I = 3 W cm-2). The rate of the sonochemical reaction increased with the rising beta-diketonate volatility and decreased with the rising hydrocarbon solvent vapor pressure. Solid sonication products consisted of a mixture of thorium carbide ThC2 and Th(IV) beta-diketonate partial degradation products. The average ThC2 particle size was estimated to be about 2 nm. ThC2 formation was attributed to the high-temperature reaction occurring within the cavitating bubble. The thorium beta-diketonate partial degradation products formed in the liquid reaction zones surrounding the cavitating bubbles.
authors.affiliation: Institute of Physical Chemistry, Russian Academy of Sciences, Moscow, Russia. nikitenko@ipc.rssi.ru
authors.forename: S I
authors.initials: SI
authors.lastname: Nikitenko
authors.forename: P
authors.initials: P
authors.lastname: Moisy
authors.forename: I A
authors.initials: IA
authors.lastname: Tcharushnikova
authors.forename: P
authors.initials: P
authors.lastname: Blanc
authors.forename: C
authors.initials: C
authors.lastname: Madic