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91.
Sakai H Fujioka J Fukuda T Okuyama D Hashizume D Kagawa F Nakao H Murakami Y Arima T Baron AQ Taguchi Y Tokura Y 《Physical review letters》2011,107(13):137601
We report a ferroelectric transition driven by the off-centering of magnetic Mn(4+) ions in antiferromagnetic Mott insulators Sr(1-x)Ba(x)MnO(3) with a perovskite structure. As x increases, the perovskite lattice shows the typical soft-mode dynamics, as revealed by the momentum-resolved inelastic x-ray scattering and far-infrared spectroscopy, and the ferroelectricity shows up for x ≥ 0.45. The observed polarization is comparable to that for a prototypical ferroelectric BaTiO(3). We further demonstrate that the magnetic order suppresses the ferroelectric lattice dilation by ~70% and increases the soft-phonon energy by ~50%, indicating the largest magnetoelectric effects yet attained. 相似文献
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Panatarani Camellia Lenggoro I. Wuled Okuyama Kikuo 《Journal of nanoparticle research》2003,5(1-2):47-53
LiNO3 was used as a shield in the preparation of single crystalline ZnO particles by a spray pyrolysis process in order to prevent agglomeration and enhance the crystallinity of the ZnO. LiNO3 was added to a precursor solution of zinc acetate dihydrate prior to its atomization by means of an ultrasonic transducer. Agglomerate-free particles having a mean particle size of 26 nm were successfully obtained after washing the product. X-ray diffractometry, field-emission scanning electron micrograph and transmission electron micrograph data indicate that the size and morphology of ZnO were strongly influenced by the operating temperature used and the residence time of the particle in the reactor. 相似文献
97.
Itaru Mita Hiroshi Okuyama 《Journal of polymer science. Part A, Polymer chemistry》1971,9(12):3437-3452
Anionic living polymerization of α-methylstyrene containing a small amount of THF (less than 10%) was studied at temperatures between ?30°C and 50°C. At any temperature studied, a certain quantity of monomer remained without further polymerization. The effect of temperature and THF content on the final state was completely different in low and high temperature regions; at temperatures lower than ca. 20°C, the final monomer concentration decreased with increasing polymerization temperature and THF content. This is explained by the concept of “stopping of polymerization due to vitrification” of the polymerizing mixture. In fact, the final reaction mixture is really glassy in most cases and the red color of living polymer buried in the glass is discolored only very slowly when exposed to air. Detailed analysis of the results showed that the vitrification stopping holds only approximately. At temperatures higher than ca. 30°C, a normal equilibrium between propagation and depropagation holds, and the final monomer concentration increased with temperature. It is, however, far less than the equilibrium monomer concentration obtained in solution polymerization at the same temperature, and it increased appreciably with the increase in THF content. It is shown that the behavior of the equilibrium for the whole concentration range can be explained satisfactorily by a thermodynamic theory of ternary mixture. 相似文献
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Small projections of KCl grown on the tungsten substrate from the saturated solution were observed by field-emission microscopy in an ultrahigh vacuum. The observed fieldemission patterns consisted of many bright spots with different sizes and brightness, and some of the bright spots repeated periodically disappearance and reappearance under the application of a constant voltage at lower temperatures. The spots increased in number and in brightness as the applied voltage and the substrate temperature were increased. A phenomenon which seems to be a kind of vacuum arc was frequently observed with a periodicity and its period was found to decrease with increasing the applied voltage. 相似文献
100.
Y. Matsui M. Okuyama M. Noda Y. Hamakawa 《Applied Physics A: Materials Science & Processing》1982,28(3):161-166
Interface states in the ferroelectric-semiconductor junction have been investigated from analyses of DLTS andC-V data. Two trap levels are located at 0.21 and 0.36 eV below the conduction band near the silicon side of the interface in the MFS (Metal-Ferroelectric-Semiconductor) structure. The interface states density has been drastically reduced by putting an oxide layer between ferroelectric and semiconductor with certain heat treatment in H2 atmosphere at 500 °C. It has been found that the MFMOS (Metal-Ferroelectric-Metal-Oxide-Semiconductor) structure shows the least interface states density (less than 1011cm–2eV–1) with the maximal dielectric constant of PbTiO3 thin films. 相似文献