The Olivine-type LiFePO_4 was prepared by sonochemical method starting from LiOH・H_2O, (NH_4)_2HPO_4 and FeSO_4・7H_2O. Ultrasonic irradiation upon the solution of raw materials was able to synthesize fine particles of LiFePO_4 and prohibit the conversion of Fe^<2+> to Fe^<3+> in the solution without using a reducing agent. The prepared LiFePO_4 was characterized by XRD and SEM. The shape of the sample was a globular structure and the particle size of that was homogeneous and under sub-micron. The temperature of the solution is an important factor to synthesis LiFePO_4 by the sonochemical reaction. Discharge behavior of LiFePO_4 synthesized sonochemical reaction at 60℃ of the solution temperature exhibited 113mAhg^<-1> in the range of 4.0-3.0V vs. Li/Li^+ at a current rate of 0.2C. The ultrasonic effects on the precipitation of the LiFePO_4 precursor in the solution are very complicated, but one of them may helps nucleation of the LiFePO_4 precursor as a consequence of the collision among solute raw materials.

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A novel pulse sonoelectrochemical method for the size-controlled synthesis of conducting polymer microspheres was developed. This new methodology involves the deposition of conducting polymer microspheres on the electrode during the electric pulse, and then their exfoliation by the coming sonic pulse. In this system, the size of conducting polymer microspheres could be controlled by adjusting the electrolysis time. As a result, we have succeeded in preparing size-controlled conducting polymer microspheres ranging from 0.4 to 2.4μm in diameter. The electrochemical properties of the conducting polymer microspheres obtained by the present method were also investigated.

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Microbubble is generic name of the bubble that has diameter of smaller than tens of μm. It has specific feature that the rising velocity of bubble is slower compared to standard bubble, and therefore suspended time in column is much longer. But after the ultrasonic is applied to the microbubble liquid, milky liquid made by pressurization solution process, deformation of microbubble is instantly occurred, and suddenly liquid becomes clear like before microbubbles generated. In this study, we analyzed this phenomenon through the pictures taken by a high-speed video camera, the measurement of a bubble size distribution, and establishing logical explanation of the mechanism. The coalescence of microbubbles can be observed by visualizing analysis while ultrasonic irradiates. Moreover, the rising velocity of microbubbles depends on SDS concentration, and the suspended time is longer as SDS concentration increases.

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In this paper, the author shows about the development of ultrasonic standards and future works at National Metrology Institute of Japan (NMIJ). By the beginning of 2006, both ultrasonic power standard and ultrasonic pressure standard have been established. These standards will be used mainly for medical ultrasonic diagnosis and treatment. Recently, in the fields of sonochemistry and medicine, high-power and high-pressure ultrasounds have been used. However, the measurement standards have not yet been established not only in Japan but also other countries because of difficulties of the measurements. At NMIJ, we have begun to prepare some new researches for ultrasonic measurements and standards for high power and high pressure ultrasound. For ultrasonic power measurement, as conventional radiation force balance method cannot work correctly at high power ultrasound due to thermal effect or acoustic streaming, alternative methods should be required. The calorimetry method with distilled water may become one of the suitable methods. Robust and stable hydrophones used in high pressure ultrasound field will also become key devices for medical ultrasound and sonochemistry.

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Various phenolic compounds were synthesized using ultrasonication in order to shorten the reaction time and get the good yields in mild condition. Our ultrasonication reactions were applied to the hydroxylation of phenols, oxidation reaction with Mn(III), C(II) and lipase. Various ketones were reacted with TiCl_4 and Zn under ultrasonication to give the corresponding coupling dimmers. Ketones were substituted with methoxy, hydroxy, acetoxy and bromine on the benzene ring. Using ultrasonication, the reaction time and yield of the reductive coupling reaction were changed better. Typical reaction was as follows. Substituted acetophenones were dissolved in THF. The solution was added with TiCl_4 and Zn in THF at 0℃ and the reaction mixture was ultrasonicated under argon. The reaction mixture was added by sodium hydrogencarbonate and the solution was extracted and the products were isolated. Various pinacols were produced concomitantly with pinacolones which were obtained with acid catalysis, TiCl_4. All structural determination of these products was done using NMR, IR, MS and X-ray analysis. The reaction with or without ultrasonication was extremely different in the reaction time. 4'-Hydroxy or 4'-methoxyacetophenone were reacted very easily with ultrasonication to give the corresponding substituted pinacols. Pinacols substituted with phenols were easily synthesized using ultrasonication.

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Numerical simulations of bubble pulsations have been performed in order to study the experimentally observed bubble motion under an ultrasonic horn by high-speed video camera. The comparison between the calculated results and the experimental observation of the bubble pulsation has indicated that the bubble pulsation is strongly influenced by surrounding bubbles which change the velocity field in the liquid by their pulsations. The expansion of a bubble during the rarefaction phase of ultrasound is strongly reduced by the interaction with surrounding bubbles. Some bubbles move toward the horn tip due to the secondary Bjerkens force acting from the bubbles near the horn tip. It has also been shown that the acoustic amplitude in the liquid is strongly reduced by cavitation due to the decrease in acoustic radiation resistance.

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Small-angle X-ray scattering measurements of ethanol/water droplets in mist generated by ultrasonic atomization were carried out at SPring-8. Using He carrier gas instead of air, smaller droplets were generated from ethanol of < 20mol%, while larger droplets were generated from ethanol of > 20mol%, suggesting that generation of the droplets are highly affected by the carrier gas.

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Ultrasonic polymerization behaviors of methyl 2-acetamidoacrylate (MAA) and methyl 2-propionamidoacrylate (MPA) were examined. The molecular weight and molecular weight distribution were 3.6×10^5 and 3.0, respectively, for PMAA obtained in the polymerization in aqueous solution at [MAA]=0.7M at 12℃ for 180min. When sodium sulfate was added to this solution ([Na_2SO_4]=0.65M), the reaction solution became clouded after ultrasonic irradiation and polymer adhered to the surface of solution and the side of the glass cell. The molecular weight was 9.1×10^5 and molecular weight distribution was 2.3 under this condition. The effect of additive salts is discussed in relation to the phase transition of these polymers. The ultrasonic polymerization of MPA was performed and the results are discussed in view of the difference in the monomer/polymer structures and polymerization behaviors.

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