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91.
Osami Yanagisawa Mitsuru Izumi Wei-Zhi Hu Kenji Nakanishi Hideo Nojima 《Journal of Superconductivity》1999,12(1):311-315
Electron-spin resonance (ESR) for the charge-ordered state in well-characterized Pr0.65Ca0.35MnO3 exhibited significant change of both the absorption profile and the effective spin susceptibility upon injection of laser light with photon energy of 1.17 eV provided by Nd-YAG laser. The increase of the effective spin susceptibility was clearly found out thanks to the injection of photons in the temperature range 90 K–80 K, which is below the transition temperature from the antiferromagnetic charge ordered state to the canted antiferromagnetic spin alternation state, T
CAF125 K. The temperature dependence of the change of the ESR profile excludes the possibility of heating by laser light. The present result suggests that a kind of photo-induced insulator–metal transition may occur due to propagation of the delocalized carriers via probable double exchange interaction in the charge-ordering collapsed state created by the injection of photons. 相似文献
92.
Osami Yanagisawa Mitsuru Izumi Wei-Zhi Hu Kenji Nakanishi Hideo Nojima 《Journal of Superconductivity》1999,12(1):307-310
The magnetic behavior of the distorted perovskite manganese, Pr0.65Ca0.35MnO3 was studied by X-band electron spin resonance for powder samples. We observed the onset of the charge-ordered state at T
CO215 K, the antiferromagnetic transition with the peak of the ESR linewidth, H
p–p
at T
AF180 K and the canted antiferromagnetic transition at T
CAF125 K associated with the abrupt increase of both the effective magnetization and H
p–p
. Below 90 K, the absorption intensity profile becomes weakened with decreasing temperature suggesting the existence of some kind of magnetic disorder below 90 K, which is responsible for a part of evidence of the existence of the spin-glass state as has been proposed by Yoshizawa et al., Phys. Rev. B
52, 1689 (1996). 相似文献
93.
M Okazaki H Tohda T Yanagisawa M Taira J Takahashi 《Canadian Metallurgical Quarterly》1998,19(7-9):611-616
Two types of heterogeneous fluoridated apatites, H-F and F-H, were synthesized by supplying fluoride over the whole range of the degree of fluoridation (X = 0-1.0) during the initial or final half of the experimental period. Although X-ray diffraction patterns and scanning electron microscopy (SEM) photographs of both H-F and F-H type apatites were not significantly different, high-resolution transmission electron microscopy (HR-TEM) showed quite different features; H-F type apatites were elongated hexagons with electron beam damage in the core, while F-H type apatites were rather wider hexagons and approached the typical hexagon of fluorapatite. These results supported the previous speculations on the two different types of heterogeneous fluoridated hydroxyapatites synthesized with fluoride concentration stoichiometrically equivalent to that of fluorapatite: hydroxyapatite covered with fluorapatite and fluorapatite covered with hydroxyapatite. The apparent solubility of H-F type apatites decreased with increases in degree of fluoridation, while that of F-H type apatites decreased markedly and then remained almost constant. 相似文献
94.
95.
96.
Takeshi Kuroki Takashi Sawaguchi Kazumasa Suzuki Shoaki Ide Tadashi Ikemura 《Polymer》1983,24(4):428-432
The distribution of double bonds in thermally degraded polyisobutylene was determined quantitatively by using pulsed Fourier transform 1H n.m.r. spectroscopic analysis. The double bonds in the degraded polymer did not exist in the interior but at the terminal positions of the polymer chain. These olefins were of the terminal trisubstituted and terminal vinylidene types. The content of the former was much greater than that of the latter. This shows that radical chain transfer predominantly occurs at the methylene hydrogen rather than at the methyl groups of the polymer chain. The average number of double bonds per molecule, f, was greater than 1 and tended to be near 2. Thereby most of the degraded polyisobutylene was shown to have two terminal unsaturations per molecule. 相似文献
97.
98.
Transparent La0.33NbO3 flakes were fabricated by a rapid quenching technique. The quenched La0.33NbO3 phase takes a simple cubic perovskite structure and cation vacancies are randomly distributed on the A sites. The cubic La0.33NbO3 phase is a new modification which is different from the well-known orthorhombic phase with ordered A-site vacancies. Transparent flakes were found to show the predominant orientation of (110) and (220) planes. 相似文献
99.
Summary The permeation characteristics of polymer blend membranes from poly(vinylidene fluoride) and poly-(ethylene glycol) to aqueous polymer solution were investigated under carefully controlled conditions. The permeation characteristics were influenced significantly by the blend ratio, the temperature and time of heat treatment, which changed the structure of the resulting membranes. 相似文献
100.
Hydrothermal crystal growth of perovskite-type fluorides 总被引:1,自引:0,他引:1
Shigeyuki S¯omiya Shin -Ichi Hirano Masahiro Yoshimura Kazumichi Yanagisawa 《Journal of Materials Science》1981,16(3):813-816
Single crystals of perovskite-type fluorides were grown from potassium fluoride and di-valent metal chloride solutions by
a hydrothermal method under a temperature gradient, at maximum temperature 600° C and pressure 98 MPa. Single-crystal cubes
of KMnF3, KFeF3, KCoF3 and KZnF3, of cube edge sizes ranging from 0.2 to 2.0 mm, were grown. Crystals of KNiF3 grew in rectangular prisms and those of KCdF3 in anhedral form. Single crystals of KCuF3 were grown in pure water from co-precipitated KCuF3 powder. KMgF3 crystals were not grown by this method. 相似文献