New Theoretical Insight into Fluorination and Fluorine–Fluorine Interactions as a Driving Force in Crystal Structures

2020 ◽  
Vol 20 (5) ◽  
pp. 2943-2951
Author(s):  
Goran V. Janjić ◽  
Stefan T. Jelić ◽  
Nemanja P. Trišović ◽  
Dragan M. Popović ◽  
Ivana S. Đorđević ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Driving Force ◽  
Fluorine Interactions ◽  
Theoretical Insight ◽  
Insight Into

Theoretical insight into the CdS/FAPbI3 heterostructure: a promising visible-light absorber

2021 ◽  
Author(s):  
Junli Chang ◽  
Liping Jiang ◽  
Guangzhao Wang ◽  
Yuhong Huang ◽  
Hong Chen
Keyword(s):  
Optical Absorption ◽  
Visible Light ◽  
Visible Light Range ◽  
Light Absorber ◽  
Absorption Performance ◽  
Theoretical Insight ◽  
Insight Into

The optical absorption performance of the perovskite FAPbI3 in the visible-light range is significantly improved by constructing a CdS/FAPbI3 heterostructure.

scholarly journals Theoretical Insight into the Reversal of Chemoselectivity in Diels-Alder Reactions of α,β-Unsaturated Aldehydes and Ketones Catalyzed by Brønsted and Lewis Acids

Organics ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 38-49
Author(s):  
Lakhdar Benhamed ◽  
Sidi Mohamed Mekelleche ◽  
Wafaa Benchouk
Keyword(s):  
Lewis Acids ◽  
Major Product ◽  
Diels Alder ◽  
Unsaturated Ketone ◽  
Unsaturated Aldehydes ◽  
Aldehydes And Ketones ◽  
Theoretical Insight ◽  
Insight Into ◽  
Good Agreement

Experimentally, a reversal of chemoselectivity has been observed in catalyzed Diels–Alder reactions of α,β-unsaturated aldehydes (e.g., (2E)-but-2-enal) and ketones (e.g., 2-hexen-4-one) with cyclopentadiene. Indeed, using the triflimidic Brønsted acid Tf2NH as catalyst, the reaction gave a Diels–Alder adduct derived from α,β-unsaturated ketone as a major product. On the other hand, the use of tris(pentafluorophenyl)borane B(C6F5)3 bulky Lewis acid as catalyst gave mainly the cycloadduct of α,β-unsaturated aldehyde as a major product. Our aim in the present work is to put in evidence the role of the catalyst in the reversal of the chemoselectivity of the catalyzed Diels–Alder reactions of (2E)-but-2-enal and 2-Hexen-4-one with cyclopentadiene. The calculations were performed at the ωB97XD/6-311G(d,p) level of theory and the solvent effects of dichloromethane were taken into account using the PCM solvation model. The obtained results are in good agreement with experimental outcomes.

scholarly journals Creating polar antivortex in PbTiO3/SrTiO3 superlattice

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Adeel Y. Abid ◽  
Yuanwei Sun ◽  
Xu Hou ◽  
Congbing Tan ◽  
Xiangli Zhong ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Phase Field ◽  
Driving Force ◽  
Topological Phase ◽  
Phase Field Simulation ◽  
Topological Structures ◽  
Field Simulation ◽  
Condensed Matters ◽  
Topological Phase Transitions ◽  
Insight Into

AbstractNontrivial topological structures offer a rich playground in condensed matters and promise alternative device configurations for post-Moore electronics. While recently a number of polar topologies have been discovered in confined ferroelectric PbTiO3 within artificially engineered PbTiO3/SrTiO3 superlattices, little attention was paid to possible topological polar structures in SrTiO3. Here we successfully create previously unrealized polar antivortices within the SrTiO3 of PbTiO3/SrTiO3 superlattices, accomplished by carefully engineering their thicknesses guided by phase-field simulation. Field- and thermal-induced Kosterlitz–Thouless-like topological phase transitions have also been demonstrated, and it was discovered that the driving force for antivortex formation is electrostatic instead of elastic. This work completes an important missing link in polar topologies, expands the reaches of topological structures, and offers insight into searching and manipulating polar textures.

Über einige Beziehungen zwischhen Kristallstrukturen

1956 ◽  
Vol 11 (11) ◽  
pp. 920-934b
Author(s):  
Konrad Schubert
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Spatial Correlation ◽  
Chemical Elements ◽  
Electron Gas ◽  
Lattice Constants ◽  
Hexagonal Close Packed ◽  
Binary Compounds ◽  
Atomic Radii ◽  
Insight Into

In determining structures we use physical propositions in order to find a likely crystal structure. The same propositions are of value for the ordering of known structures into a natural system. The atomic radii form such a proposition. Another proposition is contained in the spatial correlation of electrons in the electron gas. The question is, whether this correlation is of influence on the crystal structure or not. To gain a first insight into this question, it is useful to know whether the crystal structures are physically compatible with a certain spatial correlation of electrons. Some qualitative rules are given to assess the physical possibility of a spatial correlation of electrons in a crystal structure. For the crystal structures of some chemical elements proposals for electron correlation are given. These proposals account for rationalities existing between some lattice constants, e. g. the axial ratios of the hexagonal close packed structures of Co and Zn. The proposals are also applicable to some binary compounds. With regard to these commensurabilities, it seems possible that the examination of the spatial correlation of electrons may lead to a better understanding of the crystal-chemical empiry.

What makes court-referred mediation effective?

2014 ◽  
Vol 25 (1) ◽  
pp. 21-37 ◽  
Author(s):  
Amira Galin
Keyword(s):  
Design Methodology ◽  
Content Type ◽  
Process And Outcome ◽  
Refusal To Participate ◽  
The Impact ◽  
Practical Implications ◽  
Theoretical Insight ◽  
Insight Into ◽  
Low Rate

Purpose – The purpose of this paper is to obtain insight into court-referred mediation in the Israeli Labor Courts, by analyzing its processes and outcomes, as a function of tactics used by both the disputants and the mediator. Design/methodology/approach – Observation of 103 court-referred mediations, for each of which a detailed process and outcome were documented. Data on disputants' refusal to participate in the mediation was also collected. At the end of each mediation case, disputants were given a questionnaire in which they expressed their satisfaction with the outcome and their evaluation of the mediator's contribution. Findings – A low rate of refusal to participate in court-referred mediation was found. Also, the higher the ratio of soft tactics to pressure tactics employed (by all parties involved) during the process, the higher the rate of agreements. Mediators use significantly more soft tactics than disputants, and are more active in using tactics. The two significant variables that predict the mediation's agreement are the ratio between soft tactics to pressure tactics used by all parties, and mediator contribution to the process. Practical implications – The significant role of soft tactics in the process, outcome, and satisfaction of court-referred mediation may serve as a guideline for disputants and mediators. Originality/value – This unique research, which examines the impact of tactics on court-referred mediation, may provide added and significant theoretical insight into its process and outcome, as well as a better understanding of other “hybrid” (compulsory at the beginning, voluntary at the end) mediations.

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