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M. Kokta 《Journal of solid state chemistry》1973,8(1):39-42
An increased solubility of Nd3+ in YAG has been achieved by means of expansion of its crystal lattice with Sc3+ ions substituting for Al3+ ions in the octahedral sites. A number of other scandium substituted rare earth aluminum garnets of general formula {R3}[Sc2](Al3)O12 have been prepared and results are compared with similar compounds in {R3}[Sc2](Fe3)O12 systems. It is shown that the expansion of the YAG lattice by octahedral substitution significantly increases the solubility of Nd3+ on dodecahedral sites. The results of substitution of Sc in other rare earth-aluminum systems appear to be consistent with results obtained in the yttrium-aluminum system and so ions bigger than Gd3+, such as Eu3+ and Sm3+, can form garnets {Eu3}[Sc2](Al3)O12 and {Sm3}[Sc2](Al3)O12. 相似文献
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A series of pulps containing between 3.6 and 23% of lignin was prepared by a careful delignification of a high-yield bisulfite pulp. The pulps were subjected to isothermal pyrolysis in a Perkin-Elmer TGS-1 thermobalance. The measurements were carried out at 8 different temperatures from 325 to 360°C under nitrogen atmosphere. The results obtained indicate that the effect of lignin on degradation depends strongly on temperature. Below 330°C, the rate of degradation varied only little with lignin. This variation becomes more important at temperatures above 330°C in that the rate of degradation increases with decreasing lignin content. The apparent activation energy of degradation ranges from 41.4 kcal mol?1 at 23% of lignin to 67.0 kcal mol?1 at 3.7% of lignin. 相似文献
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It has been found possible to prepare garnets with magnetic trivalent rare-earth ions filling all or most dodecahedral sites while nonmagnetic Sc3+ ions fill all octahedral sites and magnetic Fe3+ ions fill all or most tetrahedral sites. Phase-pure garnets found include {RE3?yScy}[Sc2](Fe3)O12, where RE is Sm, Eu, Gd, Tb, or Dy, and y can be zero with Sm and Eu; {Nd3}[Sc2](FezGa3?z)O12; and other NdScFe garnets with small amounts of Y, Gd, or Lu added in order to bring z up to 3. Results are interpreted in terms of “size factor” and “comfort factor.” 相似文献
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Number of 59·5 keV-photons per decay of241Am equal to 0·355±0·003 was determined from activity and gamma-emission rate measurements. 相似文献
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Abstract AC and DC electrical measurements between 273 and 800 K were used to characterize the electrical conductivity of Al2O3: Mg single crystals containing [Mg]0 centers. At low fields contacts are blocking. At high fields, electrical current flows steadily through the sample and the I–V characteristic corresponds to a directly biased barrier with a series resistance (bulk resistance). AC measurements yield values for the junction capacitance as well as for the sample resistance, and provide reproducible conductivity values. The conductivity varies linearly with the [Mg]0 concentration and a thermal activation energy of 0.67 eV was obtained, which agrees very well with the activation energy previously reported for the motion of free holes. 相似文献
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The conversion coefficient
K=1·48±0·07 and the total conversion coefficient = =8·05±0·2 have been determined by means of the 4 scintillation counter.The authors are obliged to Mrs.Boukalov, Mrs.Vladykov and MissStíteská for the assistance in the elaboration of this paper. 相似文献
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