scholarly journals Mn ions' site and valence in PbTiO3 based on the native vacancy defects

2021 ◽  
Vol 24 (2) ◽  
pp. 23705
Author(s):  
H. Xin ◽  
Q. Pang ◽  
D. L. Gao ◽  
L. Li ◽  
P. Zhang ◽  
...  
Keyword(s):  
First Principles ◽  
Formation Energy ◽  
Lattice Distortion ◽  
First Principles Calculations ◽  
Equilibrium Conditions ◽  
Vacancy Defects ◽  
Domain Movement ◽  
Ion Substitution ◽  
A Site ◽  
Mn Doped

Mn ions' doping site and valence were studied in PbTiO3 (PT) with the native vacancy defects by the first-principles calculations. Firstly, the native vacancy defects of Pb, O and Ti in PT were investigated and it was found that Pb vacancy is preferred to others. And then the growth of Mn doped PT should be preferred to Mn ion substituting for an A-site Pb ion with +3 valence when Pb is deficient under equilibrium conditions driven solely by minimization of the formation energy, and this could result in a larger lattice distortion of PT. In addition, when Mn enters the Pb site, the electronegativity of O becomes weaker which makes the domain movement easier in PT to improve the performance of PT, while Mn ion substitution for a B-site Ti ion is the opposite.

Electronic and magnetic properties of F atoms adsorbed on TiO2:Mn(001) diluted magnetic semiconductor surfaces: First-principles calculations

2014 ◽  
Vol 28 (18) ◽  
pp. 1450096 ◽  
Author(s):  
Chunlei Wang ◽  
Dan Li ◽  
Yuan Niu ◽  
Hongmin Zhao ◽  
Chunjun Liang
Keyword(s):  
First Principles ◽  
Formation Energy ◽  
Diluted Magnetic Semiconductor ◽  
Magnetic Moments ◽  
Magnetic Semiconductor ◽  
First Principles Calculations ◽  
Ion Doping ◽  
Diluted Magnetic ◽  
The Stability ◽  
Mn Doped

We performed first-principles calculations for two Mn -doped structures in which Mn atoms substitute Ti atoms to determine whether (i) it is more conducive to Mn ion doping and (ii) ferromagnetism can occur in F adsorption anatase TiO 2 surfaces. Ferromagnetic (FM) coupling is more stable than antiferromagnetic (AFM) coupling for all doping configurations as the adsorption of F atoms on the surface significantly lowers the formation energy of the TiO 2: Mn system. The magnetic moments of the Mn ions are reduced, whereas those of O atoms on the surface are increased. The magnetic moment of the O atoms is mainly derived from the spin polarization p x and p y orbitals. F adsorption promotes doping of Mn atoms and to a certain extent improves the stability of the structure, magnetism and metallicity.

scholarly journals Anion ordering and vacancy defects in niobium perovskite oxynitrides

2021 ◽  
Vol 2 (7) ◽  
pp. 2398-2407
Author(s):  
Joshua J. Brown ◽  
Youxiang Shao ◽  
Zhuofeng Ke ◽  
Alister J. Page
Keyword(s):  
First Principles ◽  
First Principles Calculations ◽  
Defect Engineering ◽  
Vacancy Defects ◽  
The Stability

First-principles calculations predict the stability and mobility of vacancy defects in niobium perovskite oxynitrides, aiding defect engineering for enhanced photocatalysis.

Electronic Structure and Optical Properties of a Mn-Doped InSe/WSe2 van der Walls Heterostructure: First Principles Calculations

2020 ◽  
Vol 77 (7) ◽  
pp. 587-591
Author(s):  
Rundong Liang ◽  
Xiuwen Zhao ◽  
Guichao Hu ◽  
Weiwei Yue ◽  
Xiaobo Yuan ◽  
...  
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
First Principles ◽  
First Principles Calculations ◽  
Mn Doped

scholarly journals Effect of Defects on Spontaneous Polarization in Pure and Doped LiNbO3: First-Principles Calculations

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 100 ◽  
Author(s):  
Weiwei Wang ◽  
Dahuai Zheng ◽  
Mengyuan Hu ◽  
Shahzad Saeed ◽  
Hongde Liu ◽  
...  
Keyword(s):  
Spontaneous Polarization ◽  
First Principles ◽  
Density Functional ◽  
Lattice Distortion ◽  
Stable Structure ◽  
First Principles Calculations ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Specific Configuration ◽  
The Relationship

Numerous studies have indicated that intrinsic defects in lithium niobate (LN) dominate its physical properties. In an Nb-rich environment, the structure that consists of a niobium anti-site with four lithium vacancies is considered the most stable structure. Based on the density functional theory (DFT), the specific configuration of the four lithium vacancies of LN were explored. The results indicated the most stable structure consisted of two lithium vacancies as the first neighbors and the other two as the second nearest neighbors of Nb anti-site in pure LN, and a similar stable structure was found in the doped LN. We found that the defects dipole moment has no direct contribution to the crystal polarization. Spontaneous polarization is more likely due to the lattice distortion of the crystal. This was verified in the defects structure of Mg2+, Sc3+, and Zr4+ doped LN. The conclusion provides a new understanding about the relationship between defect clusters and crystal polarization.

scholarly journals First principles calculations of the thermodynamic stability of Ba, Zr, and O vacancies in BaZrO3

RSC Advances ◽  
2019 ◽  
Vol 9 (59) ◽  
pp. 34158-34165 ◽  
Author(s):  
N. Raja ◽  
D. Murali ◽  
S. V. M. Satyanarayana ◽  
M. Posselt
Keyword(s):  
Temperature Dependence ◽  
Thermodynamic Stability ◽  
First Principles ◽  
Formation Energy ◽  
First Principles Calculations ◽  
Reservoir Conditions ◽  
Charge States ◽  
Atomic Reservoir

The temperature dependence of the free formation energy of Ba, Zr and O vacancies in BaZrO3 is investigated for all possible charge states and atomic reservoir conditions.

First-principles study on the stability and magnetoelectric properties of multiferroic materials XTiO3 (X = Mn, Fe, Co, Ni)

2018 ◽  
Vol 32 (09) ◽  
pp. 1850105 ◽  
Author(s):  
Xing-Yuan Chen ◽  
Guo-Xia Lai ◽  
Di Gu ◽  
Wei-Ling Zhu ◽  
Tian-Shu Lai ◽  
...  
Keyword(s):  
Magnetic Property ◽  
First Principles ◽  
Phonon Dispersion ◽  
Critical Conditions ◽  
First Principles Calculations ◽  
Multiferroic Materials ◽  
Equilibrium Conditions ◽  
Magnetoelectric Properties ◽  
Strong Hybridization ◽  
The Stability

The XTiO3 (X = Mn, Fe, Co and Ni) materials with R3c structure could be grown under critical conditions based on first-principles calculations and thermodynamic stability analysis. FeTiO3 and MnTiO3 could be synthesized relatively easily under metal-rich and O-poor conditions, while NiTiO3 could be stable under Ni-rich, O-rich and Ti-poor conditions. The predicted R3c CoTiO3 under thermodynamic equilibrium conditions is suggested to be synthesized under Co-rich, O-rich and Ti-poor conditions, but the calculated phonon dispersion indicates R3c CoTiO3 becomes unstable under the dynamical conditions. The ferroelectric behavior in the XTiO3 (X = Mn, Fe, Co and Ni) system could be dominated by the Ti ion with d0 state and the strong hybridization between Ti and O, while the magnetic property is mainly caused by the contribution of 3d transition metal.

scholarly journals Identification of a monoclinic metallic state in VO2 from a modified first-principles approach

2019 ◽  
Vol 33 (12) ◽  
pp. 1950148
Author(s):  
Yongcheng Liang ◽  
Ping Qin ◽  
Zhiyong Liang ◽  
Lizhen Zhang ◽  
Xun Yuan ◽  
...  
Keyword(s):  
First Principles ◽  
Lattice Distortion ◽  
Insulator Transition ◽  
Metallic State ◽  
Strongly Correlated ◽  
Electron Systems ◽  
First Principles Calculations ◽  
Monoclinic Structure ◽  
Metal Insulator Transition ◽  
Metal Insulator

Metal-insulator transition (MIT) underlies many remarkable and technologically important phenomena in VO2. Even though its monoclinic structure had before been the reserve of the insulating state, recent experiments have observed an unexpected monoclinic metallic state. Here, we use a modified approach combining first-principles calculations with orbital-biased potentials to reproduce the correct stability ordering and electronic structures of different phases of VO2. We identify a ferromagnetic monoclinic metal that is likely to be the experimentally observed mysterious metastable state. Furthermore, the calculations show that an isostructural insulator-metal electronic transition is followed by the lattice distortion from the monoclinic structure to the rutile one. These results not only explain the experimental observations of the monoclinic metallic state and the decoupled structural and electronic transitions of VO2, but also provide a useful understanding for the metal-insulator transition in other strongly correlated d electron systems.

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