Prediction and hydrogen acceleration of ordering in iron-vanadium alloys.
نویسندگان
چکیده
Ab initio calculations of binary metallic systems often predict ordered compounds in contrast to empirical reports of solid solutions or disordered phases. These discrepancies are usually attributed to slow kinetics that retains metastable structures at low temperatures. The Fe-V system is an example of this phenomenon, in which we predict two ordered stable ground states, Fe3V and FeV3, whereas a disordered σ phase is reported. We propose to overcome this difficulty by hydrogen absorption, which facilitates metal atom mobility through vacancy formation and separation between the two elements due to their opposite affinities towards it, thus accelerating transformation kinetics. Hydrogen also increases the relative stability of the ordered structures compared with that of the σ phase without affecting the shape of the phase diagram. The hydrogen-induced formation of the ordered structures is expressed by a reversible decrease of the electrical resistivity with increasing hydrogen pressure. Such behavior has not been reported before in thin H absorbing films. Formation of the ordered structures is further substantiated by the kinetics of the resistivity changes upon variation of the hydrogen pressure, where two stages are distinguished: a fast initial stage and a much slower subsequent process in which the resistivity changes direction, associated with hydrogen dissolution and phase transformation, respectively.
منابع مشابه
Nano composite mixed-addenda vanadium substituted polyoxometalate-TiO2 as a green, reusable and efficient catalyst for rapid and efficient synthesis of symmetric disulfides under ultrasound irradiation
Mixed-addenda vanadium substituted polyoxometalate supported on anatase TiO2 crushed nano leaf was synthesized by an unusual reaction with titanium tetraisopropoxide at 100 ºC via sol–gel method under oil-bath condition. The materials characterized by XRD, TEM, IR and UV–vis techniques. In the present work, efficient oxidative of thiols with polyoxometalate-TiO2/hydrogen peroxide ...
متن کاملComparison of doped combination zirconium-tungsten, zirconium- molybdenum and molybdenum-tungsten on single-wall vanadium oxide nanotube in hydrogen gas adsorption
In this study, doped vanadium oxide nanotubes were evaluated using different software to study the absorption of hydrogen gas. Vanadium oxide nanotubes are one of the options for absorption and storage hydrogen gas. In this research study for the first time, the Monte Carlo simulation was used to investigate the hydrogen gas absorption behavior in molybdenum-tungsten, molybdenum-zirconium and z...
متن کاملQuantum Theoretical studies of Nanostructures onto Hydrogen Adsorption on V-surface
We have studied the adsorption processes of H2 on the V (100) surface of Vanadium using self consistent field theory.Dissociative adsorptions of H2 are significantly favored compared to molecular adsorptions. There is a significant charge transfer from the first layer of the vanadium surface to the Hydrogen atoms. Three possible adsorption sites, top, bridge and center site, were considered in ...
متن کاملSelective oxidation of sulfides to sulfoxides by a vanadium-based catalyst using 30% hydrogen peroxide
The vanadium-based catalyst, acts as a homogeneous catalyst for the selective oxidation of various kinds of sulfides with 30% aqueous H2O2. Vanadium-based catalyst was successfully used as the oxygen source for the oxidation of sulfides to sulfoxides for the first time. The sulfoxides were obtained in a good way to high yields without any detectable over-oxidation to sulfones under normal condi...
متن کاملOn the Twist Effect of V-h Alloys Associated with the Precipitation of Hydrides
A vanadium wire containing hydrogen begins to twist by itself, when cooled, at the onset of hydride precipitation. The magnitude of the twist is greatly increased, if the specimen is plastically deformed in torsion prior to observations. The effect of the elastic stress is systematically studied by observing the zero point drift on cooling and heating under the applied torque; both the precipit...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Physical review letters
دوره 108 21 شماره
صفحات -
تاریخ انتشار 2012