New three-dimensionalk→·p→model for the electronic structure ofA−15compounds and application to anomalous properties ofV3Si andNb3Sn in the cubic phase

1978 ◽  
Vol 17 (12) ◽  
pp. 4931-4941 ◽  
Author(s):  
Ting-Kuo Lee ◽  
Joseph L. Birman
Keyword(s):  
Electronic Structure ◽  
Cubic Phase

Fundamental Studies of Plutonium Aging

MRS Bulletin ◽  
2001 ◽  
Vol 26 (9) ◽  
pp. 679-683 ◽  
Author(s):  
Brian D. Wirth ◽  
Adam J. Schwartz ◽  
Michael J. Fluss ◽  
Maria J. Caturla ◽  
Mark A. Wall ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Conduction Band ◽  
Ambient Pressure ◽  
Radioactive Decay ◽  
Bound State ◽  
Environmental Safety ◽  
Structure Theory ◽  
Cubic Phase ◽  
High Symmetry ◽  
Safety And Health

Plutonium metallurgy lies at the heart of science-based stockpile stewardship. One aspect is concerned with developing predictive capabilities to describe the properties of stockpile materials, including an assessment of microstructural changes with age. Yet, the complex behavior of plutonium, which results from the competition of its 5f electrons between a localized (atomic-like or bound) state and an itinerant (delocalized bonding) state, has been challenging materials scientists and physicists for the better part of five decades. Although far from quantitatively absolute, electronic-structure theory provides a description of plutonium that helps explain the unusual properties of plutonium, as recently reviewed by Hecker. (See also the article by Hecker in this issue.) The electronic structure of plutonium includes five 5f electrons with a very narrow energy width of the 5f conduction band, which results in a delicate balance between itinerant electrons (in the conduction band) or localized electrons and multiple lowenergy electronic configurations with nearly equivalent energies. These complex electronic characteristics give rise to unique macroscopic properties of plutonium that include six allotropes (at ambient pressure) with very close free energies but large (∼25%) density differences, a lowsymmetry monoclinic ground state rather than a high-symmetry close-packed cubic phase, compression upon melting (like water), low melting temperature, anomalous temperature-dependence of electrical resistance, and radioactive decay. Additionally, plutonium readily oxidizes and is toxic; therefore, the handling and fundamental research of this element is very challenging due to environmental, safety, and health concerns.

scholarly journals Thermodynamic Parameters of PbTe Crystals: DFT-Calculations

2015 ◽  
Vol 16 (1) ◽  
pp. 28-33
Author(s):  
D. M. Freik ◽  
B. P. Volochanska ◽  
T. O. Parashchuk
Keyword(s):  
Density Functional Theory ◽  
Free Energy ◽  
Electronic Structure ◽  
Thermodynamic Parameters ◽  
Quantum Chemical ◽  
Density Functional ◽  
Cubic Phase ◽  
Functional Theory ◽  
Temperature Dependences ◽  
Analytical Expressions

Based on the analysis of the crystal NaCl type and electronic structure of cubic phase CdS crystals the cluster models have been built for calculation of the geometric and thermodynamic parameters. According to density functional theory (DFT) and using the hybrid valence base set B3LYP the temperature dependence of the energy ΔE and the enthalpy ΔH of formation, Gibbs free energy ΔG, entropy ΔS, specific heat at constant volume CV and pressure CP of the crystals have been found. The analytical expressions of the temperature dependences of presented thermodynamic parameters which was approximated from the quantum- chemical calculations data and with using mathematical package Maple 14 have been received.

Probing the Electronic Structure of Hybrid Perovskites in the Orientationally Disordered Cubic Phase

2020 ◽  
Vol 11 (14) ◽  
pp. 5719-5727 ◽  
Author(s):  
Pronoy Nandi ◽  
S. K. Pandey ◽  
Chandan Giri ◽  
Vijay Singh ◽  
L. Petaccia ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Cubic Phase

scholarly journals Photocurrent generation in carbon nanotube/cubic-phase HfO2 nanoparticle hybrid nanocomposites

2016 ◽  
Vol 7 ◽  
pp. 1075-1085 ◽  
Author(s):  
Protima Rauwel ◽  
Augustinas Galeckas ◽  
Martin Salumaa ◽  
Frédérique Ducroquet ◽  
Erwan Rauwel
Keyword(s):  
Electronic Structure ◽  
Hybrid Material ◽  
Visible Region ◽  
Hybrid Nanocomposites ◽  
Intrinsic Defect ◽  
Cubic Phase ◽  
Free Standing ◽  
Photocurrent Generation ◽  
Defect Sites ◽  
Resonance Band

A hybrid material consisting of nonfunctionalized multiwall carbon nanotubes (MWCNTs) and cubic-phase HfO2 nanoparticles (NPs) with an average diameter of 2.6 nm has been synthesized. Free standing HfO2 NPs present unusual optical properties and a strong photoluminescence emission in the visible region, originating from surface defects. Transmission electron microscopy studies show that these NPs decorate the MWCNTs on topological defect sites. The electronic structure of the C K-edge in the nanocomposites was probed by electron energy loss spectroscopy, highlighting the key role of the MWCNT growth defects in anchoring HfO2 NPs. A combined optical emission and absorption spectroscopy approach illustrated that, in contrast to HfO2 NPs, the metallic MWCNTs do not emit light but instead expose their discrete electronic structure in the absorption spectra. The hybrid material manifests characteristic absorption features with a gradual merger of the MWCNT π-plasmon resonance band with the intrinsic defect band and fundamental edge of HfO2. The photoluminescence of the nanocomposites indicates features attributed to combined effects of charge desaturation of HfO2 surface states and charge transfer to the MWCNTs with an overall reduction of radiative recombination. Finally, photocurrent generation under UV–vis illumination suggests that a HfO2 NP/MWCNT hybrid system can be used as a flexible nanodevice for light harvesting applications.

Electronic Structure and Lattice Dynamics of BaCeO3 Compound in Cubic Phase

2014 ◽  
Vol 43 (11) ◽  
pp. 4301-4307 ◽  
Author(s):  
Murat Aycibin ◽  
Bahattin Erdinc ◽  
Harun Akkus
Keyword(s):  
Electronic Structure ◽  
Lattice Dynamics ◽  
Cubic Phase

Electronic structure of the high-temperature cubic phase of SrFeO2.5

JETP Letters ◽  
2015 ◽  
Vol 102 (5) ◽  
pp. 307-311 ◽  
Author(s):  
M. A. Korotin ◽  
V. M. Zainullina ◽  
V. L. Kozhevnikov
Keyword(s):  
Electronic Structure ◽  
High Temperature ◽  
Cubic Phase

Electronic structure of the cubic phase of zirconium dioxide

1994 ◽  
Vol 34 (5) ◽  
pp. 701-705
Author(s):  
A. E. Krasovskii ◽  
A. S. Katashinskii ◽  
N. V. Parkhomenko
Keyword(s):  
Electronic Structure ◽  
Zirconium Dioxide ◽  
Cubic Phase

scholarly journals Fe-doped effects on phase transition and electronic structure of CeO2 under compressed conditions from ab initio calculations

2021 ◽  
Vol 127 (10) ◽  
Author(s):  
Karnchana Sathupun ◽  
Komsilp Kotmool ◽  
Prutthipong Tsuppayakorn-aek ◽  
Prayoonsak Pluengphon ◽  
Arnab Majumdar ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Electronic Structure ◽  
Ab Initio ◽  
Orthorhombic Phase ◽  
Cubic Phase ◽  
Fe Doping ◽  
Lattice Constants ◽  
High Pressure Phase Transition ◽  
Average Bond

AbstractAb initio study of high-pressure phase transition and electronic structure of Fe-doped CeO2 with Fe concentrations of 3.125, 6.25, and 12.5 at% has been reported. At a constant-pressure consideration, the lattice constants and the volume of the supercell were decreased with an increasing concentration of Fe. The average bond length of Fe–O is lower than that of Ce–O. As a result, Fe doping induces the reduced volume of the cell, which is in good agreement with previous experiments. At high pressure (~ 30 GPa), it was found that the transition pressure from the fluorite to the cotunnite orthorhombic phase decreases at a higher concentration of Fe, indicating that the formation energy of the compound is induced by Fe-doping. Furthermore, compression leads to interesting electronic properties too. Under higher pressures, the bandgap increases in the cubic structure under compression and then suddenly plummets after the transition to the orthorhombic phase. The 3d states of Fe mainly induced the impurity states in the bandgap. In both the undoped and Fe-doped systems, the bandgap increased in the cubic phase at high pressure, while the gap and p-d hybridization decrease in the orthorhombic phase.

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