Thermodynamic aspects of transition metals doped ZnO

2011 ◽  
Vol 1309 ◽  
Author(s):  
David Sedmidubský ◽  
Zdeněk Sofer ◽  
Štěpán Huber ◽  
Jindřich Leitner
Keyword(s):  
Transition Metals ◽  
Ab Initio ◽  
Thermodynamic Data ◽  
Elevated Temperatures ◽  
Mixed Oxides ◽  
Enthalpies Of Formation ◽  
Full Potential ◽  
Substitution Defect ◽  
End Members ◽  
Relevant Range

ABSTRACTWe present a thermodynamic study of selected transition metals (TM=Cr, Mn, Fe and Co) solubility in ZnO based on the assessment of available thermodynamic data and ab-initio calculations in the respective TM-Zn-O systems. The ab-initio DFT calculations of enthalpies of formation of the involved phases and the energies of substitution defect (TM-Zn) formation were performed using the full-potential APW+lo technique (WIEN2k code) within GGA+U approximation. The calculated energies of mixed oxides and virtual (unstable) TMO end-members of (Zn,TM)O solid solutions are referred to well established thermodynamic data of binary oxides taken from SGTE database. The assessed thermodynamic data are subsequently used for calculation of phase equilibria and construction of the respective pO2-T-x phase (FactSage software). Whereas the solubility of Mn, Fe, and Co in ZnO is found not to exceed 1 mol% at low temperatures (T<900°C), the homogeneity range is substantially enlarged at elevated temperatures (~10 mol% at the eutectic temperature). By contrast, the solubility of Cr turned out to be negligible in the relevant range of T and pO2.

Thermodynamic Data of Iodine Reactions Calculated by Quantum Chemistry. Training Set of Molecules

2008 ◽  
Vol 73 (10) ◽  
pp. 1340-1356 ◽  
Author(s):  
Katarína Mečiarová ◽  
Laurent Cantrel ◽  
Ivan Černušák
Keyword(s):  
Quantum Chemistry ◽  
Ab Initio ◽  
Thermodynamic Data ◽  
Theoretical Calculations ◽  
Reactor Core ◽  
Fission Products ◽  
Vapour Phase ◽  
Reactor Accident ◽  
Training Set ◽  
Coolant System

This paper focuses on the reactivity of iodine which is the most critical radioactive contaminant with potential short-term radiological consequences to the environment. The radiological risk assessments of 131I volatile fission products rely on studies of the vapour-phase chemical reactions proceeding in the reactor coolant system (RCS), whose function is transferring the energy from the reactor core to a secondary pressurised water line via the steam generator. Iodine is a fission product of major importance in any reactor accident because numerous volatile iodine species exist under reactor containment conditions. In this work, the comparison of the thermodynamic data obtained from the experimental measurements and theoretical calculations (approaching "chemical accuracy") is presented. Ab initio quantum chemistry methods, combined with a standard statistical-thermodynamical treatment and followed by inclusion of small energetic corrections (approximating full configuration interaction and spin-orbit effects) are used to calculate the spectroscopic and thermodynamic properties of molecules containing atoms H, O and I. The set of molecules and reactions serves as a benchmark for future studies. The results for this training set are compared with reference values coming from an established thermodynamic database. The computed results are promising enough to go on performing ab initio calculations in order to predict thermo-kinetic parameters of other reactions involving iodine-containing species.

Modelling the thermodynamic data for hcp Zn and Cu–Zn alloys– an ab initio and calphad approach

Calphad ◽  
2021 ◽  
Vol 72 ◽  
pp. 102253
Author(s):  
Alan Dinsdale ◽  
Alexandra Khvan ◽  
Ekaterina A. Smirnova ◽  
Alena V. Ponomareva ◽  
Igor A. Abrikosov
Keyword(s):  
Ab Initio ◽  
Thermodynamic Data ◽  
Calphad Approach ◽  
Zn Alloys

scholarly journals Ab Initio Prediction of the Redox Potentials of 3d Transition Metals Embedded in a Semiconducting Host Lattice

2021 ◽  
Vol 125 (7) ◽  
pp. 4267-4276
Author(s):  
William Lafargue-Dit-Hauret ◽  
Camille Latouche ◽  
Stéphane Jobic
Keyword(s):  
Transition Metals ◽  
Ab Initio ◽  
Host Lattice ◽  
Redox Potentials ◽  
Ab Initio Prediction

Electronic Structure Of (AgSb)xPbn-2xTen

2003 ◽  
Vol 793 ◽  
Author(s):  
Daniel I Bilc ◽  
S.D. Mahanti ◽  
M.G. Kanatzidis
Keyword(s):  
Electronic Structure ◽  
Ab Initio ◽  
Density Functional ◽  
Full Potential ◽  
Generalized Gradient ◽  
Two Component System ◽  
Functional Theory ◽  
Covalent Interaction ◽  
Salt Structure ◽  
Linearized Augmented Plane Wave

ABSTRACTComplex quaternary chalcogenides (AgSb)xPbn-2xTen (0<x<n/2) are thought to be narrow band-gap semiconductors which are very good candidates for room and high temperature thermoelectric applications. These systems form in the rock-salt structure similar to the well known two component system PbTe (x=0). In these systems Ag and Sb occupy Pb sites randomly although there is some evidence of short-range order. To gain insights into the electronic structure of these compounds, we have performed electronic structure calculations in AgSbTe2 (x=n/2). These calculations were carried out within ab initio density functional theory (DFT) using full potential linearized augmented plane wave (LAPW) method. The generalized gradient approximation (GGA) was used to treat the exchange and correlation potential. Spinorbit interaction (SOI) was incorporated using a second variational procedure. Since it is difficult to treat disorder in ab initio calculations, we have used several ordered structures for AgSbTe2. All these structures show semimetallic behavior with a pseudogap near the Fermi energy. Te and Sb p orbitals, which are close in energy, hybridize rather strongly indicating a covalent interaction between Te and Sb atoms.

scholarly journals Magnetic Properties and the Electronic Structure of the Gd0.4Tb0.6Co2 Compound

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5481
Author(s):  
Marcin Sikora ◽  
Anna Bajorek ◽  
Artur Chrobak ◽  
Józef Deniszczyk ◽  
Grzegorz Ziółkowski ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Magnetic Measurements ◽  
Plane Waves ◽  
Full Potential ◽  
Theory Approach ◽  
Xps Spectra

We report on the comprehensive experimental and theoretical studies of magnetic and electronic structural properties of the Gd0.4Tb0.6Co2 compound crystallization in the cubic Laves phase (C15). We present new results and compare them to those reported earlier. The magnetic study was completed with electronic structure investigations. Based on magnetic isotherms, magnetic entropy change (ΔSM) was determined for many values of the magnetic field change (Δμ0H), which varied from 0.1 to 7 T. In each case, the ΔSM had a maximum around room temperature. The analysis of Arrott plots supplemented by a study of temperature dependency of Landau coefficients revealed that the compound undergoes a magnetic phase transition of the second type. From the M(T) dependency, the exchange integrals between rare-earth R-R (JRR), R-Co (JRCo), and Co-Co (JCoCo) atoms were evaluated within the mean-field theory approach. The electronic structure was determined using the X-ray photoelectron spectroscopy (XPS) method as well as by calculations using the density functional theory (DFT) based Full Potential Linearized Augmented Plane Waves (FP-LAPW) method. The comparison of results of ab initio calculations with the experimental data indicates that near TC the XPS spectrum collects excitations of electrons from Co3d states with different values of exchange splitting. The values of the magnetic moment on Co atoms determined from magnetic measurements, estimated from the XPS spectra, and results from ab initio calculations are quantitatively consistent.

Thermodynamics of metal-ligand bond formation. XII. Adducts of Monothio-β-diketone complexes with pyridine and bipyridine

1974 ◽  
Vol 27 (6) ◽  
pp. 1351 ◽  
Author(s):  
DR Dakternieks ◽  
DP Graddon
Keyword(s):  
Thermodynamic Data ◽  
Benzene Solution ◽  
Bond Formation ◽  
Enthalpies Of Formation ◽  
Calorimetric Titration ◽  
Metal Ligand ◽  
Ligand Bond

Thermodynamic data are reported for the addition of pyridine and bipyridine in benzene solution to monothio-β-diketone complexes, ML2, of nickel(11), copper(11), zinc(11) and mercury(11). NiL2 gives NiL2(py)2 and NiL(bpy); ZnL2 gives ZnL2(py) and ZnL2(bpy); in both cases the data show that bipyridine is bidentate. CuL2 gives CuL2 (py) and CuL2 (bpy), with almost equal enthalpies of formation, but the higher stability of CuL2(bpy) shows bipyridine is probably bidentate. HgL2 gives HgL2(py) and a reaction with bipyridine which shows that an extremely unstable adduct is formed. All data were obtained by calorimetric titration.

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