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Phase diagram in the Bi-Pb-Sr-Ca-Cu-O system

Buffer effect of non-superconducting phases on oxygen exchange of the superconducting ones

Journal of Thermal Analysis and Calorimetry
Authors: A. Sebaoun, P. Satre, M. Mansori, and A. L'Honore

TG-DTA and X-ray diffraction measurements at different temperatures and under different oxygen partial pressures were carried out on the species Bi1.6Pb0.4Sr2CuO6±x, Bi1.6Pb0.4Sr2CaCu2O8±y and Bi1.6Pb0.4Sr2Ca2Cu3O10±z to analyse the influence of the oxygen chemical potential on the phase transformations. A new phase was found at isobaric invariant equilibrium for 0.5≤ /PTot≤1 at 884°C. This new phase presents a buffer effect towards oxygen exchange between superconducting oxides and the gas phase.

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Abstract  

Competing groups in a population will be integrated or segregated depending on their contest strategies. In this work a population of a fixed proportion of hawks and doves is supposed to be able to employ two different contest strategies, one more competitive than the other one. Energies are derived for populations employing these strategies and these energies depend on the availability of the resource for which hawks and doves compete. The energy for the less competitive strategy is lower than the other one when the resource is abundant. In that case hawks and doves can be in cohabitation in all proportions. If, however, the resource is scarce, the energy of the more competitive strategy is lower than the other one. In that case complete segregation of hawks and doves into colonies will result. The situation is akin to the phase pressure diagram of a binary solution with eutectic point, miscibility gap in the liquid phase and complete miscibility in the vapour phase.

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Abstract  

A systematic study of Al-Zn-Sn ternary alloys by using a Tian-Calvet calorimeter with slow heating and cooling rate was carried out and supplemented by scanning electron microscopic observations. The results have shown that crystallization coupled with dissolution of tin into the αss′ ternary solid solution on heating is an endothermic process, while melting coupled with tin expulsion on cooling is an exothermic one. It seems that the thermal effects of phase transition are outweighed by much stronger ones due to a large composition change of the αss′ ternary phase.

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The phase diagram of V2O5-MoO3-Ag2O SYSTEM

Part V. Phase diagram of the ternary system

Journal of Thermal Analysis and Calorimetry
Authors: E. Wenda and A. Bielański

Abstract  

The paper summarizes the results concerning the different parts of the ternary system V2O5-MoO3-Ag2O and presents projection of the diagram on the basal triangle as well as its three-dimensional presentation of the diagram drawn by the AutoCAD programme.

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The phase diagram of V2O5-MoO3-Ag2O system

Part IV. Molybdenum-rich part of the diagram

Journal of Thermal Analysis and Calorimetry
Authors: E. Wenda and A. Bielański

Abstract  

The results concerning the synthesis, structure and thermal properties of V2O5-MoO3-Ag2O samples in the molybdenum rich region of ternary system are presented in the form of quasi-binary systems: β-AgVO3-β-Ag2MoO4, AgVMoO6-MoO3, AgVMoO6-Ag2Mo4O13, AgVMoO6-Ag2Mo2O7, AgVMoO6-β-Ag2MoO4 and also of the system in which at V2O5/MoO3 molar ratio 3:7 the content of Ag2O was variable. The ternary phase AgVMoO6 was not described earlier in the literature.

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A new method (based on DTA and TG) for the determination of the eutectic composition is proposed for systems in which one of the components is unstable in the vicinity of the eutectic melting temperature. The eutectic composition established by means of this method for the CaCO3-CaF2 system is in very good agreement with the results obtained in a classical way.

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