High modulus oxide glasses

2015 ◽  
Vol 2015 (CICMT) ◽  
pp. 000038-000040
Author(s):  
K. Philipps ◽  
R. P. Stoffel ◽  
R. Dronskowski ◽  
R. Conradt
Keyword(s):  
Short Range ◽  
Density Functional ◽  
Elastic Moduli ◽  
Structural Changes ◽  
Glassy Phase ◽  
Oxide Glasses ◽  
High Modulus ◽  
Functional Theory ◽  
Crystalline Phases ◽  
Glassy Materials

Elastic properties of glassy materials were studied in comparison to the isochemical crystalline phases. Structural changes were studied by density-functional theory with respect to electronic, vibrational, mechanical and thermodynamic properties. It turned out that topology is essential for elastic moduli. For both, glasses and crystals, elastic moduli are a function of atomic packing density, short range order, and especially the nature of the connection of adjacent polyhedra. Both, glassy and crystalline phases, behave in a commensurable way so that the glassy phase can be handled as a member of a series of polymorphs with the same stoichiometry.

scholarly journals Defect Processes in Halogen Doped SnO2

2021 ◽  
Vol 11 (2) ◽  
pp. 551
Author(s):  
Petros-Panagis Filippatos ◽  
Nikolaos Kelaidis ◽  
Maria Vasilopoulou ◽  
Dimitris Davazoglou ◽  
Alexander Chroneos
Keyword(s):  
Electronic Properties ◽  
Tin Oxide ◽  
Density Functional ◽  
Structural Changes ◽  
High Dielectric Constant ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Optical And Electronic Properties ◽  
High Dielectric ◽  
Gap States

In the present study, we performed density functional theory calculations (DFT) to investigate structural changes and their impact on the electronic properties in halogen (F, Cl, Br, and I) doped tin oxide (SnO2). We performed calculations for atoms intercalated either at interstitial or substitutional positions and then calculated the electronic structure and the optical properties of the doped SnO2. In all cases, a reduction in the bandgap value was evident, while gap states were also formed. Furthermore, when we insert these dopants in interstitial and substitutional positions, they all constitute a single acceptor and donor, respectively. This can also be seen in the density of states through the formation of gap states just above the valence band or below the conduction band, respectively. These gap states may contribute to significant changes in the optical and electronic properties of SnO2, thus affecting the metal oxide’s suitability for photovoltaics and photocatalytic devices. In particular, we found that iodine (I) doping of SnO2 induces a high dielectric constant while also reducing the oxide’s bandgap, making it more efficient for light-harvesting applications.

scholarly journals Effect of chemical modification on electronic transport properties of carbyne

2021 ◽  
Author(s):  
G. R. Berdiyorov ◽  
U. Khalilov ◽  
H. Hamoudi ◽  
Erik C. Neyts
Keyword(s):  
Transport Properties ◽  
Electronic Transport ◽  
Density Functional ◽  
Structural Changes ◽  
Carbon Chain ◽  
Functional Formalism ◽  
Functional Theory ◽  
Carbon Allotrope ◽  
Electronic Transport Properties ◽  
Interface Structures

AbstractUsing density functional theory in combination with the Green’s functional formalism, we study the effect of surface functionalization on the electronic transport properties of 1D carbon allotrope—carbyne. We found that both hydrogenation and fluorination result in structural changes and semiconducting to metallic transition. Consequently, the current in the functionalization systems increases significantly due to strong delocalization of electronic states along the carbon chain. We also study the electronic transport in partially hydrogenated carbyne and interface structures consisting of pristine and functionalized carbyne. In the latter case, current rectification is obtained in the system with rectification ratio up to 50%. These findings can be useful for developing carbyne-based structures with tunable electronic transport properties.

EFFECTS OF SULFUR SUBSTITUTIONAL IMPURITIES ON ZnO STRUCTURE USING DENSITY FUNCTIONAL THEORY

2011 ◽  
Vol 10 (03) ◽  
pp. 381-390
Author(s):  
MANUEL ALBERTO FLORES-HIDALGO ◽  
DIANA BARRAZA-JIMÉNEZ ◽  
DANIEL GLOSSMAN-MITNIK
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Structural Changes ◽  
Theoretical Calculations ◽  
Plane Waves ◽  
Crystal Form ◽  
Functional Theory ◽  
Substitutional Impurity ◽  
Gap Energy ◽  
Other Substances

Zinc oxide ( ZnO ) electrical properties can be modified by addition of impurities or defects such as vacancies or other substances. We use sulfur ( S ) as a substitutional impurity and present a theoretical study on the characteristics of ZnO structures in its crystal form containing S in substitution of O . For theoretical calculations we used Density Functional Theory (DFT) with pseudopotentials and plane waves. ZnO in crystal form with S in substitution of O at heavy percentage was studied by analyzing properties like lattice characteristics, total energy, and gap energy. Lattice parameters a, b, c, and c/a ratio increase with the S -substituent percentage while the crystal stability decreases. Variation of gap energy shows a decreasing trend with increasing amount of substitution. In this paper, we provide a detailed data useful to identify the effects on ZnO in its crystal form when O is replaced by S that will help to predict if the structural changes on the modified ZnO structures may be suitable for applications in opto-electronics.

scholarly journals Strain-dependent structure and Raman behaviours in the heavy-ion irradiated manganite at extreme low dose

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Nam Nhat Hoang ◽  
Duc Huyen Yen Pham ◽  
The Nghia Nguyen
Keyword(s):  
Density Functional ◽  
Structural Changes ◽  
Low Dose ◽  
Blue Shift ◽  
Heavy Ion ◽  
Dynamic Calculation ◽  
Functional Theory ◽  
Lattice Dynamic Calculation ◽  
Strain Dependent ◽  
Shed Light

AbstractThe microstrains in heavy-ion irradiated manganite LaMnO3 can be managed in linear response of irradiation dose, and the corresponding internal pressure up to 8 GPa can be induced by varying doses. The response of structure under stress is studied by means of Density Functional Theory and Lattice Dynamic Calculation. All obtained Raman scattering lines are discussed in details to shed light onto structural changes during ion implantation. There appears new resonance peak at around 550 cm−1, which splits from broad features in the spectra, and attributes to the anti-symmetric vibrations of O6 cages. The blue shift of this peak scales to ~2.4 cm−1 per 1 GPa of stress. Another strong feature showing considerable blue shift is seen in the vicinity of 640 cm−1 and corresponds to one of rhombohedral distortion related soft modes. A weak mode, not frequently reported, is seen at around 420 cm−1 and corresponds to translation-like motions of fixed O6 cages.

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