scholarly journals Tailoring the multiferroic behavior in BiFeO3 nanostructures by Pb doping

RSC Advances ◽  
2016 ◽  
Vol 6 (62) ◽  
pp. 57727-57738 ◽  
Author(s):  
Kuldeep Chand Verma ◽  
R. K. Kotnala
Keyword(s):  
Oxygen Vacancies ◽  
Lone Pair ◽  
Structural Transitions ◽  
Lattice Distortions ◽  
Pb Doping

Substituting Pb2+ for Bi3+ in BiFeO3 can induce lattice distortions and structural transitions to tune the lone-pair activity for ferroelectricity and neutralized oxygen vacancies to valence Fe2+/Fe3+ ions for ferromagnetism.

Interplay of electronic reconstructions, surface oxygen vacancies, and lattice distortions in insulator-metal transition ofLaAlO3/SrTiO3

2015 ◽  
Vol 92 (12) ◽  
Author(s):  
Jun Zhou ◽  
Teguh Citra Asmara ◽  
Ming Yang ◽  
George A. Sawatzky ◽  
Yuan Ping Feng ◽  
...  
Keyword(s):  
Oxygen Vacancies ◽  
Surface Oxygen ◽  
Insulator Metal Transition ◽  
Lattice Distortions

scholarly journals Lattice distortions and oxygen vacancies produced in Au+-irradiated nanocrystalline cubic zirconia

2011 ◽  
Vol 65 (8) ◽  
pp. 675-678 ◽  
Author(s):  
Philip D. Edmondson ◽  
William J. Weber ◽  
Fereydoon Namavar ◽  
Yanwen Zhang
Keyword(s):  
Oxygen Vacancies ◽  
Cubic Zirconia ◽  
Lattice Distortions

A NEW 50 K SUPERCONDUCTOR, Tl1+xBa2−x−yLayCuO5−δ, FIRST MEMBER OF THE SERIES TlA2Cam−1CumO2m+3

1989 ◽  
Vol 03 (15) ◽  
pp. 1143-1148 ◽  
Author(s):  
C. MARTIN ◽  
D. BOURGAULT ◽  
M. HERVIEU ◽  
J. PROVOST ◽  
C. MICHEL ◽  
...  
Keyword(s):  
Rock Salt ◽  
Oxygen Vacancies ◽  
Mixed Valence ◽  
Lone Pair ◽  
Tetragonal Structure ◽  
Zero Resistance

New superconductors Tl 1+x Ba 2−x−y La y CuO 5−δ(x = 0, y = 0.6 and x = 0.25, y = 0.75) have been isolated, which exhibit a zero resistance below 50 K and a diamagnetic fraction volume ranging from 7% to 35%. Their tetragonal structure corresponds to the intergrowth of single perovskite layers with double rock-salt type layers. These latter slabs exhibit two original features, presence of oxygen vacancies and distribution of thallium over two sorts of sites. This particular behavior is discussed in terms of mixed valence of thallium, Tl(I)/Tl(III) taking into account the 6s2 lone pair of T1(I).

Mechanistic insight into oxygen vacancy migration in SrFeO3–δ from DFT+U simulations

2021 ◽  
Author(s):  
Musa Alaydrus ◽  
Ikutaro Hamada ◽  
Yoshitada Morikawa
Keyword(s):  
Oxygen Vacancy ◽  
Oxygen Reduction ◽  
Oxygen Vacancies ◽  
Structural Transitions ◽  
Ion Conductor ◽  
Vacancy Migration ◽  
Oxygen Ion ◽  
Mechanistic Insight ◽  
Oxygen Ion Conductor ◽  
Insight Into

SrFeO3–δ is known to be an effective oxygen ion conductor and oxygen vacancies are central to its performance. SrFeO3–δ displays four crystallographic structural transitions as it undergoes oxygen reduction over...

Conditions for atomic imaging of mullite

1989 ◽  
Vol 47 ◽  
pp. 418-419
Author(s):  
T. A. Epicier ◽  
G. Thomas
Keyword(s):  
Oxygen Vacancies ◽  
High Resolution Electron Microscopy ◽  
Ceramic Materials ◽  
Work Conditions ◽  
Real Space ◽  
Potential Candidate ◽  
Silicate Mineral ◽  
Resolution Electron ◽  
The Subject ◽  
Aluminium Silicate

Mullite is an aluminium-silicate mineral of current interest since it is a potential candidate for high temperature applications in the ceramic materials field.In the present work, conditions under which the structure of mullite can be optimally imaged by means of High Resolution Electron Microscopy (HREM) have been investigated. Special reference is made to the Atomic Resolution Microscope at Berkeley which allows real space information up to ≈ 0.17 nm to be directly transferred; numerous multislice calculations (conducted with the CEMPAS programs) as well as extensive experimental through-focus series taken from a commercial “3:2” mullite at 800 kV clearly show that a resolution of at least 0.19 nm is required if one wants to get a straightforward confirmation of atomic models of mullite, which is known to undergo non-stoichiometry associated with the presence of oxygen vacancies.Indeed the composition of mullite ranges from approximatively 3Al2O3-2SiO2 (referred here as 3:2-mullite) to 2Al2O3-1SiO2, and its structure is still the subject of refinements (see, for example, refs. 4, 5, 6).

Investigation of Some Characterizations of Black TiO\(_2\) Nanotubes Via Spectroscopic Methods

2019 ◽  
Vol 29 (2) ◽  
pp. 189 ◽  
Author(s):  
Tho Truong Nguyen ◽  
Thi Minh Cao ◽  
Hieu Van Le ◽  
Viet Van Pham
Keyword(s):  
Water Splitting ◽  
Oxygen Vacancies ◽  
Light Response ◽  
Nanotube Arrays ◽  
Spectroscopic Methods ◽  
Visible Light Response ◽  
Uv Visible ◽  
Visible Reflectance ◽  
Splitting Effect ◽  
Anodization Method

The black TiO\(_2\) with substantial Ti\(^3+\) and oxygen vacancies exhibit an excellent photoelectrochemical water-splitting performance due to the improved charge transport the extended visible light response. In this study, black TiO\(_2\) nanotube arrays synthesized by the anodization method, and then, they have been investigated some characterizations by spectroscopic methods such as UV-visible reflectance (UV-vis DRS), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and photoluminescence spectrum. The results showed that some highlighted properties of the black TiO2 nanotube arrays and they could apply for water-splitting effect.

On the Crystal Chemistry of Inorganic Nitrides: Crystal-Chemical Parameters and Opportunities in the Exploration of Their Compositional Space

2020 ◽  
Author(s):  
Olivier Charles Gagné
Keyword(s):  
Functional Properties ◽  
A Priori ◽  
Lone Pair ◽  
Length Variation ◽  
Electronic Effects ◽  
Statistical Knowledge ◽  
Redox Active ◽  
Multiply Bonded ◽  
Jahn Teller ◽  
Compositional Space

The scarcity of nitrogen in Earth’s crust, combined with challenging synthesis, have made inorganic nitrides a relatively-unexplored class of compounds compared to their naturally-abundant oxide counterparts. To facilitate exploration of their compositional space via <i>a priori</i> modeling, and to help <i>a posteriori</i> structure verification not limited to inferring the oxidation state of redox-active cations, we derive a suite of bond-valence parameters and Lewis-acid strength values for 76 cations observed bonding to N<sup>3-</sup>, and further outline a baseline statistical knowledge of bond lengths for these compounds. We examine structural and electronic effects responsible for the functional properties and anomalous bonding behavior of inorganic nitrides, and identify promising venues for exploring uncharted compositional spaces beyond the reach of high-throughput computational methods. We find that many mechanisms of bond-length variation ubiquitous to oxide and oxysalt compounds (e.g., lone-pair stereoactivity, the Jahn-Teller and pseudo Jahn-Teller effects) are similarly pervasive in inorganic nitrides, and are occasionally observed to result in greater distortion magnitude than their oxide counterparts. We identify inorganic nitrides with multiply-bonded metal ions as a promising venue in heterogeneous catalysis, e.g. in the development of a post-Haber-Bosch process proceeding at milder reaction conditions, thus representing further opportunity in the thriving exploration of the functional properties of this emerging class of materials.<br>

An NBO-TS predictive approach for torquoselectivity of ring opening in 3-substituted cyclobutenes

2017 ◽  
Author(s):  
Arpita Yadav ◽  
Dasari L V K Prasad ◽  
Veejendra Yadav
Keyword(s):  
Transition State ◽  
Ring Opening ◽  
Natural Bond Orbital ◽  
Theoretical Calculations ◽  
Lone Pair ◽  
Product Distribution ◽  
Acceptor Substituent ◽  
Important Contributor ◽  
Predictive Approach ◽  
Donor Substituent

<p>The torquoselectivity, the inward or outward ring opening of 3-substituted cyclobutenes, is conventionally guided by the donor and/or acceptor ability of the substituent (S). It is typically predicted by estimating the respective ring opening transition state (TS) barriers. While there is no known dissent in regard to the outward rotation of electron-rich substituents from the approaches of TS calculations, the inward rotation was predicted for some electron-accepting substituents and outward for others. To address this divergence in predicting the torquoselectivity, we have used reliable orbital descriptors through natural bond orbital theoretical calculations and demonstrated that (a) interactions <i>n</i><i><sub>S</sub></i>→s*<sub>C3C4</sub> for a lone pair containing substituent, s<sub>S</sub>→s*<sub>C3C4</sub> for a s-donor substituent, s<sub>C3C4</sub>→p*<sub>S</sub> for a resonance-accepting substituent and s<sub>C3C4</sub>→s*<sub>S</sub> for a s-acceptor substituent constitute the true electronic controls of torquoselectivity, and (b) reversibility of the ring opening event is an additional important contributor to the observed product distribution.</p>

Bond-length distributions for ions bonded to oxygen: Metalloids and post-transition metals

2017 ◽  
Author(s):  
Olivier Charles Gagné ◽  
Frank Christopher Hawthorne
Keyword(s):  
Transition Metal ◽  
Transition Metals ◽  
Metal Ions ◽  
Bond Length ◽  
Lone Pair ◽  
Transition Metal Ions ◽  
Oxygen Lone Pair

Bond-length distributions are examined for thirty-three configurations of the metalloid ions and fifty-six configurations of the post-transition-metal ions bonded to oxygen. Lone-pair stereoactivity is discussed.

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