The Structures and Electronic Properties of Composite Material (LaxAl1-X)2O3 from First-Principles Study

2012 ◽  
Vol 583 ◽  
pp. 158-161
Author(s):  
Hui Yu Yan ◽  
Yan Rui Guo ◽  
Qing Gong Song
Keyword(s):  
Dielectric Constant ◽  
Composite Material ◽  
Band Gap ◽  
Electronic Properties ◽  
First Principles ◽  
Calculation Method ◽  
High Dielectric Constant ◽  
First Principles Calculation ◽  
Al Content ◽  
High Dielectric

The structures and electronic properties of (LaxAl1-x)2O3 are studied by first-principles calculation method. The results show that the composite material (LaxAl1-x)2O3 tend to be in sixfold-coordinated structure when x0.7. (LaxAl1-x)2O3 is in disorder structure and get the minimum band gap when x equals about 0.7. It suggest that (LaxAl1-x)2O3 can be synthesized as high dielectric constant material by doping La2O3 with a lower Al dopant concentrations or by fabricating (LaxAl1-x)2O3 with rich Al content.

Optical properties and band gap characterization of high dielectric constant oxides

2012 ◽  
Vol 520 (14) ◽  
pp. 4532-4535 ◽  
Author(s):  
O. Fursenko ◽  
J. Bauer ◽  
G. Lupina ◽  
P. Dudek ◽  
M. Lukosius ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Optical Properties ◽  
Band Gap ◽  
High Dielectric Constant ◽  
High Dielectric

First Principles Investigation on the Structural, Electronic and Optical Properties of Amorphous Silica Glass

2017 ◽  
Vol 268 ◽  
pp. 92-96
Author(s):  
R.M. Nor ◽  
S.N.M. Halim ◽  
Mohamad Fariz Mohamad Taib ◽  
M. Kamil Abd-Rahman
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Electronic Properties ◽  
Amorphous Silica ◽  
First Principles ◽  
Glass Structure ◽  
Small Sample ◽  
First Principles Calculation ◽  
Electronic And Optical Properties ◽  
Amorphous Quartz

The structural, electronic, and optical properties of an amorphous SiO2 (a-SiO2) model is investigated by using first-principles calculation. Most research works used beta-cristobalite glass structure as a reference to amorphous silica structure. However, only the electronic properties were been presented without any link towards the optical properties. Here, we demonstrate simultaneous electronic and optical properties, which closely matched to a-SiO2 properties by generating small sample of amorphous quartz glass. Using the Rietveld refinement, amorphous silica structure was generated and optimized using density functional theory in CASTEP computer code. A thorough analysis of the amorphous quartz structure obtained from different thermal treatment was carried out. The structure of amorphous silica was validated with previous theoretical and experimental works. It is shown that small sample of amorphous silica have similar structural, electronic and optical properties with a larger sample. The calculated optical and electronic properties from the a-SiO2 glass match closely to previous theoretical and experimental data from others. The a-SiO2 band gap of 5.853 eV is found to be smaller than the experimental value of ~9 eV. This is due to the underestimation and assumption made in DFT. However, the band gap value is in good agreement with the other theoretical works. Apart from the absorption edge at around 6.5 eV, the refractive index is 1.5 at 0eV. Therefore, this atomic structure can served as a reference model for future research works on amorphous structures.

scholarly journals Heat-Resistant Ferroelectric-Polymer Nanocomposite with High Dielectric Constant

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1439 ◽  
Author(s):  
Nikolay Mukhin ◽  
Valentin Afanasjev ◽  
Irina Sokolova ◽  
Dmitry Chigirev ◽  
Rene Kastro ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Composite Material ◽  
High Dielectric Constant ◽  
Composite Coatings ◽  
Polymer Nanocomposite ◽  
Ferroelectric Ceramics ◽  
Frequency Spectra ◽  
Ferroelectric Polymer ◽  
Heat Resistant ◽  
High Dielectric

The high dielectric constant ferroelectric-polymer nanocomposite was developed for producing the heat-resistant and chemical stable planar layers. According to the composite coatings formation conditions, the following value ranges of dielectric constant and loss factor were received: 30–400 for dielectric constant and 0.04–0.1 for loss tangent, accordingly. Unlike of composite components, the obtained composite material is characterized by thermo-stability of electrical parameters up to 250 °C. The dielectric frequency spectra of the composite exhibit two clearly visible peaks in contrast to the spectra of the polymer and ferroelectric ceramics. The developed composite material can be used as a built-in film capacitors material in microelectronic devices.

Synthesis and investigation into the structural, electronic and electrical properties of K2Pb(OCN)I3

2019 ◽  
Vol 48 (36) ◽  
pp. 13813-13819
Author(s):  
Amira Siai ◽  
Alexandru Oprea ◽  
Markus Ströbele ◽  
Hans-Jürgen Meyer
Keyword(s):  
Dielectric Constant ◽  
Solid State ◽  
Electrical Properties ◽  
Band Gap ◽  
Solid State Reaction ◽  
High Dielectric Constant ◽  
Compound K ◽  
Direct Band Gap ◽  
Direct Band ◽  
High Dielectric

The new compound K2Pb(OCN)I3 was synthesized by the solid-state reaction of PbI2 and KOCN. Built-up form two interpenetrating tetrahedral-octahedral frameworks, it is a direct band-gap semiconductor (2.4 eV) with rather high dielectric constant.

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