scholarly journals A DFT investigation of the role of oxygen vacancies on the structural, electronic and magnetic properties of ATiO3 (A = Mn, Fe, Ni) multiferroic materials

2018 ◽  
Vol 20 (45) ◽  
pp. 28382-28392 ◽  
Author(s):  
R. A. P. Ribeiro ◽  
E. Longo ◽  
J. Andrés ◽  
S. R. de Lazaro
Keyword(s):  
Magnetic Properties ◽  
First Principles ◽  
Oxygen Vacancies ◽  
First Principles Calculations ◽  
Deep Insight ◽  
Multiferroic Materials ◽  
Multiferroic Properties ◽  
Surface Models ◽  
Insight Into

In order to achieve deep insight into the multiferroic behavior and electronic properties of intrinsic oxygen vacancies in ATiO3 (A = Mn, Fe, Ni), first-principles calculations were carried out for bulk and non-polar (110) surface models, showing that controlling oxygen vacancies can be a valuable strategy to tailor the multiferroic properties.

Solubility Products for Precipitate Phases in Steels from First-principles Calculations

2011 ◽  
Vol 1296 ◽  
Author(s):  
Tetyana Klymko ◽  
Chaitanya Krishna Ande ◽  
Marcel Sluiter
Keyword(s):  
Ab Initio ◽  
First Principles ◽  
First Principles Calculations ◽  
Experimental Phase Diagram ◽  
Formation Enthalpies ◽  
Enthalpy And Entropy ◽  
Solubility Products ◽  
Diagram Analysis ◽  
Insight Into

ABSTRACTThe work presented gives an insight into using formation enthalpies determined from ab initio calculations for computing solubility products in steels. The role of enthalpy and entropy contributions to the solubility product is discussed. As an illustration of the method, we present solubility products for observed stoichiometric precipitate phases in ferrite from first-principles calculations and in austenite as obtained from the combined approach based on ab initio and experimental phase diagram analysis. The results are compared with experimental data where available.

Adsorption and splitting of H2S on 2D-ZnO1−xNy: first-principles analysis

2014 ◽  
Vol 16 (22) ◽  
pp. 10719-10726 ◽  
Author(s):  
Summayya Kouser ◽  
Umesh V. Waghmare ◽  
Nacir Tit
Keyword(s):  
First Principles ◽  
Oxygen Vacancies ◽  
First Principles Calculations ◽  
Novel Applications ◽  
Green Fuel

Based on first-principles calculations, we report novel applications of an inorganic analogue of graphene (2D-ZnO) in the detection and capture of toxic H2S gas, its dissociation and conversion to a green fuel, hydrogen, highlighting the role of N-substitution and oxygen vacancies.

Evaluation of the role of oxygen vacancies in La3GaGe5O16:Tb3+ persistent phosphor

2017 ◽  
Vol 31 (13) ◽  
pp. 1750144 ◽  
Author(s):  
He Duan ◽  
Ze Jia Lin ◽  
You Zhong Dong ◽  
Yan Huang
Keyword(s):  
First Principles ◽  
Oxygen Vacancies ◽  
Oxygen Deficiency ◽  
Ring Structure ◽  
Persistent Luminescence ◽  
First Principles Calculations ◽  
Color Tunable ◽  
Luminescence Performance ◽  
Trap Levels

The persistent luminescence performance of a novel color-tunable Tb[Formula: see text]-doped La[Formula: see text]GaGe[Formula: see text]O[Formula: see text] phosphor has been modified by oxygen-deficiency control with an aim to explore the strategy to improve the persistent luminescence property. First-principles calculations were combined with thermoluminescence (TL) measurements to evaluate the role of oxygen vacancies in persistent luminescence of La[Formula: see text]GaGe[Formula: see text]O[Formula: see text]:Tb[Formula: see text] persistent phosphor. Our results show that the oxygen vacancies that act as an electron trap center have a limited contribution to the persistent luminescence. The formation of the ring structure of La[Formula: see text]GaGe[Formula: see text]O[Formula: see text] crystal and the resulting localized trap levels are very different from that of other outstanding persistent phosphors, like Sr[Formula: see text]MgSi[Formula: see text]O[Formula: see text], etc. Such differences are closely related to the inferior performance of La[Formula: see text]GaGe[Formula: see text]O[Formula: see text]:Tb[Formula: see text] persistent phosphor.

Theory of Point Defects and Complexes in GaN

1995 ◽  
Vol 395 ◽  
Author(s):  
Jörg Neugebauer ◽  
Chris G. Van de Walle
Keyword(s):  
First Principles ◽  
State Of The Art ◽  
Growth Parameters ◽  
Free Carrier ◽  
First Principles Calculations ◽  
Acceptor Doping ◽  
Native Defects ◽  
Chemical Potentials ◽  
Insight Into

ABSTRACTWe have studied the electronic and energetic properties of native defects, impurities and complexes in GaN applying state-of-the-art first-principles calculations. An analysis of the numerical results gives direct insight into defect concentrations and impurity solubility with respect to growth parameters (temperature, chemical potentials) and into the mechanisms limiting the doping levels in GaN. We show how compensation and passivation by native defects or impurities, solubility issues, and incorporation of dopants on other sites influence the acceptor doping levels. The role of hydrogen in enhancing the p-type doping is explained in detail. We also discuss the mechanisms responsible for the experimentally observed limitation of the free-carrier concentration in p-type GaN.

scholarly journals Oxygen Defect-Mediated Magnetism in Fe-C Codoped TiO2

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Zhaorui Zou ◽  
Zhongpo Zhou ◽  
Haiying Wang ◽  
Meng Du
Keyword(s):  
Magnetic Properties ◽  
First Principles ◽  
Spin Coating ◽  
Room Temperature ◽  
Oxygen Vacancies ◽  
Room Temperature Ferromagnetism ◽  
Sol Gel ◽  
Experimental Results ◽  
Oxygen Defect ◽  
First Principles Calculations

The magnetic properties of the C doped and C-Fe codoped TiO2films fabricated by sol-gel and spin coating have been investigated combining experiments and first-principles calculations. All the samples exhibit the anatase crystal phase and the room temperature ferromagnetism. The values of the saturation magnetizations are in the order of Fe-C codoped TiO2> Fe-C codoped TiO2(annealed in O2) > C doped TiO2> C doped TiO2(annealed in O2). The calculated net moment values are in the order of Fe-C codoped TiO2> C doped TiO2with oxygen vacancies existing, in accord with the experimental results. The hybridization of Fe 3d, C 2p,and O 2p(nearest to the Fe defect) led to the spin split of Fe 3d, C 2p,and O 2pwhich contributed to the ferromagnetism.

Distribution and self-assisted diffusion of Be and Mg impurities in ZnO

2016 ◽  
Vol 18 (29) ◽  
pp. 19631-19636 ◽  
Author(s):  
Dingyu Yong ◽  
Haiyan He ◽  
Zikang Tang ◽  
Bicai Pan
Keyword(s):  
First Principles ◽  
First Principles Calculations ◽  
Deep Insight ◽  
And Diffusion ◽  
Insight Into ◽  
Diffusion Behaviors

By performing first-principles calculations, a deep insight into the distribution and diffusion behaviors of Be and Mg impurities in ZnO is provided.

First principles calculations of optical and magnetic properties of SrFe 2 O 4 compound under pressure

2014 ◽  
Vol 378 (35) ◽  
pp. 2644-2650 ◽  
Author(s):  
Zohre Javdani ◽  
Hojat Allah Badehian ◽  
Hamdollah Salehi ◽  
Peiman Amiri
Keyword(s):  
Magnetic Properties ◽  
First Principles ◽  
First Principles Calculations ◽  
Optical And Magnetic Properties

An effective and efficient approach to p-type AlN by Be2:O codoping from first-principles calculations

2016 ◽  
Vol 30 (20) ◽  
pp. 1650257
Author(s):  
Meng Zhao ◽  
Wenjun Wang ◽  
Jun Wang ◽  
Junwei Yang ◽  
Weijie Hu ◽  
...  
Keyword(s):  
First Principles ◽  
Ionization Energy ◽  
Hole Concentration ◽  
Valence Band Maximum ◽  
First Principles Calculations ◽  
Mutual Compensation ◽  
Efficient Approach ◽  
P Type ◽  
Codoping Method

Various Be:O-codoped AlN crystals have been investigated via first-principles calculations to evaluate the role of the different combinations in effectively and efficiently inducing p-type carriers. It is found that the O atom is favored to bond with two Be atoms. The formed Be2:O complexes decrease the acceptor ionization energy to 0.11 eV, which is 0.16 eV lower than that of an isolated Be in AlN, implying that the hole concentration could probably be increased by 2–3 orders of magnitude. The electronic structure of Be2:O-codoped AlN shows that the lower ionization energy can be attributed to the interaction between Be and O. The Be–O complexes, despite failing to induce p-type carriers for the mutual compensation of Be and O, introduce new occupied states on the valence-band maximum (VBM) and hence the energy needed for the transition of electrons to the acceptor level is reduced. Thus, the Be2:O codoping method is expected to be an effective and efficient approach to realizing p-type AlN.

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