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- Author or Editor: T. Shigematsu x
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Abstract
Fullerenes, C60 and C70, were irradiated by 8 and 10 MeV deuterons. The irradiated samples were dissolved in CS2 and filtered to remove insoluble by-products. Finally, radioactive fullerenes and products, such as fullerene dimers, trimers labeled with13N, were isolated and detected in the liquid phase by radiochromatography. This suggests that the energy rich13N atoms successfully incorporated into the fullerene cages and that the disrupted cages reacted with neighboring cages.
Summary Specific heats on the single crystals of Sr2Nb2O7, Sr2Ta2O7 and (Sr1-xBax)2Nb2O7 were measured in a wide temperature range of 2-600 K. Heat anomalies of a λ-type were observed at the incommensurate phase transition of T INC (=495 K) on Sr2Nb2O7 and at the super-lattice phase transition of T SL (=443 K) on Sr2Ta2O7; the transition enthalpies and the transition entropies were estimated. Furthermore, a small heat anomaly was observed at the low temperature ferroelectric phase transition of T LOW (=95 K) on Sr2Nb2O7. The transition temperature T LOW decreases with increasing Ba content x and it vanishes for samples of x>2%.
Summary The phase diagram of the mixed crystal (K1-xRbx)2SeO4 was determined by means of thermal analysis and neutron scattering experiments. The hexagonal to orthorhombic phase transition line exists for any x. The normal-incommensurate phase transition temperature decreases continuously with increasing Rb content. However, the incommensurate-commensurate phase transition was not observed except for K2SeO4. According to the clear softening of the Σ2- Σ 3 phonon branches and the finite frequency at 0 K for x>0.34, an existence of the hypothetical phase transition was confirmed.
Abstract
The composition of superconducting oxide, BaPb1–xBixO3 (BPB), was analyzed in order to decide the accurate x value. Oxygen and barium were determined non-destructively by3He and neutron activation analysis. Lead and bismuth were determined by substoichiometric isotope dilution analysis. Precision was within 3%. The x value determined xd, was larger than the initial composition, x.
