Metastability of NbN in the ordered vacancy NbO phase.
نویسندگان
چکیده
A metastable phase of NbN with superconducting T c =16.4 K was reported recently by Treece and collaborators. The reported structure of the thin film sample deviates from the rocksalt (B1) NbN structure with 25% ordered vacancies on each sublattice (space group Pm3m) and a lattice constant of 4.442Å. Using full potential electronic structure methods, we contrast the electronic structure with that of B1 NbN. The calculated energy, 1.00 eV/molecule higher than B1 NbN, and calculated lattice constant of 4.214Å indicate that the new phase must be something other than the ordered stoichiometric Pm3m phase.
منابع مشابه
Polymorphism and metastability in NbN: Structural predictions from first principles.
We use ab initio pseudopotential total energy calculations with a plane wave basis set to investigate the structural energetics of various phases of polymorphic NbN. Particular attention is given to its recently discovered superconducting phase with a Tc of 16.4 K, reported to have the NbO structure type. Results of total energy calculations show that it is in fact energetically unfavorable for...
متن کاملThe Generalized Maxwell-Stefan Model Coupled with Vacancy Solution Theory of Adsorption for Diffusion in Zeolites
It seems using the Maxwell-Stefan (M-S) diffusion model in combination with the vacancy solution theory (VST) and the single-component adsorption data provides a superior, qualitative, and quantitative prediction of diffusion in zeolites. In the M-S formulation, thermodynamic factor (Г) is an essential parameter which must be estimated by an adsorption isotherm. Researchers usually utilize the ...
متن کاملDFT Study on Oxygen-Vacancy Stability in Rutile/Anatase TiO2: Effect of Cationic Substitutions
In this study, a full-potential density functional theory was used to investigate the effects of Ti substitution by different cations. In both rutile and anatase, Ti atom was replaced by Ce, Au, Sn, Ag, Mo, Nb, Zr, and Y. Phase stability, electronic structure and formation energy of oxygen vacancy were compared for rutile and anatase. The results indicated that substitution of Ce and Zr increas...
متن کاملFormation mechanism of superconducting phase and its three-dimensional architecture in pseudo-single-crystal KxFe2â‹TMySe2
We report how the superconducting phase forms in pseudo-single-crystal KxFe2−ySe2. In situ scanning electron microscopy (SEM) observation reveals that, as an order-disorder transition occurs, on cooling, most of the high-temperature iron-vacancy-disordered phase gradually changes into the iron-vacancy-ordered phase, whereas a small quantity of the high-temperature phase retains its structure an...
متن کاملThe simultaneous effect of 3d impurities of transition metals and oxygen vacancy defect on TiO2 anatase and rutile
In this work, the formation of oxygen-vacancy defect in 3d metals-doped TiO2 anatase and rutile structures is first investigated. The systematic calculations of formation energy, crystalline stability, band structure and density of state (DOS) of TiO2 samples of anatase and rutile doped with 3d transition metals with and without oxygen defect is done using FHI-aims as a software package based o...
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. B, Condensed matter
دوره 52 12 شماره
صفحات -
تاریخ انتشار 1995