HUANG Dianbing
,
KONG Lingtan
,
LIN ZongcaiUniversity of Science and Technology Beijing
,
Beijing. China
金属学报(英文版)
The oxidation rate of magnetite concentrate is ery quick at the reaction beginning, but it becomes much slower when the reaction is conducted to a certain level because the product layer on the micro particles resists the oxygen diffusion greatly. This phenomena are proved through experiments. And a function is put forward to calculating the quivalent osmosing thickness of the product layer. Based on the function, a mathematical model is established for the whole range reaction process of magnetite in pellets. It is proved that this model fits the real process very well under any condition.
关键词:
Magnetite
,
null
,
null
Physica B-Condensed Matter
The structural, mechanical, thermodynamics properties and phase transition of FeVSb are investigated extensively using the first principle calculations and the quasi-harmonic Debye model. From the calculated elastic constants of cubic FeVSb, some other mechanical quantities, such as bulk modulus and Poisson's ratio, are drawn. Surprisingly, it is found that almost all these mechanical quantities are larger than those of CoVSb (Bo Kong et al., J. Alloys Compd. 509 (2011) 2611); the obtained corresponding transition pressure from fcc to hcp is also larger than that of CoVSb. For these distinctions, their complete different electronic and magnetic behaviors in their cubic structures may be responsible. However, in their hexagonal structures, atomic configurations are similar in terms of the analysis of both the ground-state structure and enthalpy-pressure curves. It is also shown that the elastic instability of cubic FeVSb does not appear with pressure upto 120 GPa and should not be a reason for the pressure-induced phase transition. In addition, heat capacity, Debye temperatures, and so on are obtained successfully for cubic FeVSb under the quasi-harmonic Debye model. Furthermore, we attempt to explore the phase diagram of FeVSb with the model. (C) 2011 Elsevier B.V. All rights reserved.
关键词:
FeVSb;Mechanical properties;Thermodynamics properties;Phase;transition;Generalized gradient approximation;semi-heusler compounds;ab-initio calculations;electronic-structure;elastic-constants;thermoelectric-materials;transport-properties;crystals;pressure;gap;instabilities
