Polarisation charge switching through the motion of metal atoms trapped in fullerene cages

2014 ◽  
Vol 16 (43) ◽  
pp. 23869-23873 ◽  
Author(s):  
G. Raggi ◽  
A. J. Stace ◽  
E. Bichoutskaia
Keyword(s):  
Stable States ◽  
Endohedral Fullerenes ◽  
Large Group ◽  
Metal Atoms ◽  
Molecular Cages

Calcium containing endohedral fullerenes are representative of a large group of molecular cages, which can be reversibly toggled between two stable states defined by the distribution of the polarisation charge.

Methods for the Synthesis of Endohedral Fullerenes

2021 ◽  
Vol 21 (4) ◽  
pp. 2446-2459
Author(s):  
Nazym Yerlanovna Akhanova ◽  
Dmitry Viktorovich Shchur ◽  
Anatoly Petrovich Pomytkin ◽  
Alexander Dmitrievich Zolotarenko ◽  
Anatoly Dmitrievich Zolotarenko ◽  
...  
Keyword(s):  
Plasma Temperature ◽  
Inert Atmosphere ◽  
Metal Alloys ◽  
Synthesis Methods ◽  
Metal Carbide ◽  
Energy Potential ◽  
Endohedral Fullerenes ◽  
Metal Atoms ◽  
Wide Range ◽  
Electric Arc Process

In the present manuscript the authors show the progress recorded regarding the main synthesis methods of metal endo-fullerenes. Shown, that nowadays, the most productive and common method of producing endohedral fullerenes is the electric arc process due to the fact that (a) it is simple enough to introduce atoms into the plasma from solids and gases; (b) its performance is the highest among other methods; (c) gives a wide range of produced types of metallofullerenes in an inert atmosphere-mono-, di-, tri-metalfullerenes, metal carbide clusters, in a reactive atmosphere (N2, NH3)-metal nitride and cyanide clusters, heterofullerenes; (d) provides the greatest energy potential, which is likely to allow the introduction into the cells of fullerene molecules metal atoms with higher ionization energies than titanium (≥7 eV). The yield of metal endofullerenes is substantially higher than the “empty” fullerenes. In this case, the stabilization of both metal atoms and fullerene cells occurs. The quantitative and qualitative output of MEF is significantly affected by: (a) conditions of the process in the reactor: the gas pressure, its flow rate, temperature, amperage; the distance between the electrodes, and others, that is, those factors that determine the plasma temperature and the residence time of the reaction particles in it; (b) the composition of solid additives (salts, oxides, metal alloys) in the graphite anode and their quantitative (mol) ratio with carbon; (c) replacement of the inert atmosphere of the synthesis with the active one (helium-with nitrogen, ammonia, water vapor, CO and other gases).

scholarly journals Structural Studies of Giant Empty and Endohedral Fullerenes

2020 ◽  
Vol 8 ◽  
Author(s):  
Song Wang ◽  
Qing Chang ◽  
Guizhi Zhang ◽  
Fukun Li ◽  
Xingmin Wang ◽  
...  
Keyword(s):  
Fullerene Cage ◽  
Intramolecular Electron Transfer ◽  
Structural Studies ◽  
Single Crystal Diffraction ◽  
Comprehensive Overview ◽  
Endohedral Fullerenes ◽  
Practical Solution ◽  
X Ray ◽  
Metal Atoms ◽  
Chloro Derivatives

Structure elucidations of giant fullerenes composed of 100 or more carbon atoms are severely hampered by their extremely low yield, poor solubility and huge numbers of possible cage isomers. High-temperature exohedral chlorination followed by X-ray single crystal diffraction studies of the chloro derivatives offers a practical solution for structure elucidations of giant fullerenes. Various isomers of giant fullerenes have been determined by this method, specially, non-classical giant fullerenes containing heptagons generated by the skeletal transformations of carbon cages. Alternatively, giant fullerenes can be also stabilized by encapsulating metal atoms or clusters through intramolecular electron transfer from the encapsulated species to the outer fullerene cage. In this review, we present a comprehensive overview on synthesis, separation and structural elucidation of giant fullerenes. The isomer structures, chlorination patterns of a series of giant fullerenes C2n (2n = 100-108) and heptagon-containing non-classical fullerenes derived from giant fullerenes are summarized. On the other hand, giant endohedral fullerenes bearing different endohedral species are also discussed. At the end, we propose an outlook on the future development of giant fullerenes.

Novel Structure of Fullerenes and Endohedral Fullerenes

2003 ◽  
Vol 775 ◽  
Author(s):  
Chun-Ru Wang ◽  
Chun-Li Bai ◽  
Hisanori Shinohara
Keyword(s):  
Molecular Magnet ◽  
Spectroscopic Techniques ◽  
Hplc Separation ◽  
X Ray Diffraction ◽  
Endohedral Fullerenes ◽  
X Ray ◽  
Metal Atoms ◽  
Novel Structure ◽  
First Time ◽  
Novel Structures

AbstractBy using Krätschmer-Huffman synthesis and HPLC separation method we have isolated a series of novel fullerenes and endohedral fullerenes. Various spectroscopic techniques, e.g., MS, NMR, UV-vis-NIR, TEM, X-ray diffraction spectrometry etc., were adopted to characterize the isolated fullerenes. Several fullerenes were revealed to hold novel structures and electronic properties. For examples, C80(D5d) was isolated and characterized to have an ellipsoidal structure which is in fact one of the shortest SW-nanotubes; The isolation of Sc2@C66 breaks the well-known isolated-pentagon-rule (IPR) for the first time, which shows that the unconventional fullerenes may be dramatically stabilized through encaging metal atoms; Sc2C2@C84 is a novel molecular endohedral fullerene in which the Sc2C2 cluster rotates rapidly along the main C2 axis of C84(D2d). This fullerene is predicted to be a molecular magnet and may be used as nano-switcher in electronics.

Zone-axis ALCHEMI for the rapid assessment of site occupancies in garnets

1986 ◽  
Vol 44 ◽  
pp. 706-707
Author(s):  
M.T. Otten ◽  
P.R. Buseck
Keyword(s):  
Single Crystals ◽  
Rapid Assessment ◽  
Site Occupancy ◽  
Zone Axis ◽  
Synthetic Compounds ◽  
X Ray ◽  
Large Group ◽  
Crystallographic Planes

ALCHEMI (Atom Location by CHannelling-Enhanced Microanalysis) is a TEM technique for determining site occupancies in single crystals. The method uses the channelling of incident electrons along specific crystallographic planes. This channelling results in enhanced x-ray emission from the atoms on those planes, thereby providing the required site-occupancy information. ALCHEMI has been applied with success to spinel, olivine and feldspar. For the garnets, which form a large group of important minerals and synthetic compounds, the channelling effect is weaker, and significant results are more difficult to obtain. It was found, however, that the channelling effect is pronounced for low-index zone-axis orientations, yielding a method for assessing site occupancies that is rapid and easy to perform.

Incommensurate modulated phases of the NbxTa1-xTe4 charge density wave system

1992 ◽  
Vol 50 (1) ◽  
pp. 58-59
Author(s):  
S. Ritchie ◽  
J. C. Bennett ◽  
A. Prodan ◽  
F.W. Boswell ◽  
J.M. Corbett
Keyword(s):  
Charge Density ◽  
Charge Density Wave ◽  
Direct Evidence ◽  
Density Wave ◽  
Wave System ◽  
Modulated Phases ◽  
Metal Atoms ◽  
Incommensurate Modulation ◽  
End Members ◽  
Modulation Wave Vector

A continuous sequence of compounds having composition NbxTa1-xTe4; 0 ≤ x ≤ 1 have been studied by electron diffraction and microscopy. Previous studies have shown that the end members of the series, TaTε4 and NbTε4 possess a quasi-one-dimensional character and exhibit charge density wave (CDW) distortions. In these compounds, the subcell structure is tetragonal with axes (a × a × c) and consists of the metal atoms (Nb or Ta) centered within an extended antiprismatic cage of Te atoms. At room temperature, TaTε4 has a commensurate modulation structure with a 2a × 2a × 3c unit cell. In NbTε4, an incommensurate modulation with × ∼ 16c axes is observed. Preliminary studies of the mixed compounds NbxTα1-xTε4 showed a discontinuous jump of the modulation wave vector commensurate to incommensurate when the Nb dopant concentration x, exceeded x ≃ 0.3, In this paper, the nature of the compositional dependence of is studied in greater detail and evidence is presented for a stepwise variation of . This constitutes the first direct evidence for a Devil's staircase in CDW materials.

Ultra high resolution SEM at high voltage images individual fab fragments applied as molecular label to cell surface receptors

1989 ◽  
Vol 47 ◽  
pp. 70-71
Author(s):  
Klaus-Ruediger Peters
Keyword(s):  
High Resolution ◽  
High Energy ◽  
Metal Coating ◽  
Beam Diameter ◽  
Surface Receptors ◽  
Surface Mobility ◽  
Metal Atoms ◽  
Shadowing Effect ◽  
Imaging Mode ◽  
Deposition Techniques

Topographic ultra high resolution can now routinely be established on bulk samples in cold field emission scanning electron microscopy with a second generation of microscopes (FSEM) designed to provide 0.5 nm probe diameters. If such small probes are used for high magnification imaging, topographic contrast is so high that remarkably fine details can be imaged on 2DMSO/osmium-impregnated specimens at ribosome surfaces even without a metal coating. On TCH/osmium-impregnated specimens topographic resolution can be increased further if the SE-I imaging mode is applied. This requires that beam diameter and metal coating thickness be made smaller than the SE range of ~1 nm and background signal contributions be reduced. Subnanometer small probes can be obtained (only) at high accelerating voltages. Subnanometer thin continuous metal films can be produced under the following conditions: self-shadowing effect between metal atoms must be reduced through appropriate deposition techniques and surface mobility of metal atoms must be diminished through high energy sputtering and/or specimen cooling.

An ecological basis for large group size in Colobus angolensis in the Nyungwe Forest, Rwanda

2001 ◽  
Vol 39 (1) ◽  
pp. 83-92 ◽  
Author(s):  
Cheryl Fimbel ◽  
Amy Vedder ◽  
Ellen Dierenfeld ◽  
Felix Mulindahabi
Keyword(s):  
Group Size ◽  
Large Group ◽  
Colobus Angolensis ◽  
Ecological Basis

Pengembangan Bahan Ajar Matematika Bisnis Berbasis Komputer Untuk Mahasiswa Jurusan Akuntansi Politeknik Negeri Bali

Epigram ◽  
2019 ◽  
Vol 16 (2) ◽  
pp. 99-110
Author(s):  
I Made Wijana ◽  
Anak Agung Putri Suardani ◽  
I Gede Made Karma
Keyword(s):  
Small Group ◽  
Mathematics Teaching ◽  
Needs Analysis ◽  
Average Score ◽  
Teaching Materials ◽  
Initial Product ◽  
Large Group ◽  
Computer Based ◽  
Large Groups ◽  
Expert Validation

This research aims to produce prototype of computer-based business mathematics teaching materials to improve student achievement of Accounting Department, Politeknik Negeri Bali (PNB). In this research, to reach the target of teaching materials of computer-based business mathematics, the development using Borg and Gall method with some modifications into five steps: needs analysis and curriculum majoring in accounting, initial product development, education expert validation, small group trial , and large group trials. Trial of small group and large group by involving first semester student of Diploma IV Managerial Accounting Study Program, Accounting Department, PNB. Based on curriculum analysis and needs analysis, teaching materials are developed in the form of modules with Microsoft Excel application and the result of the initial product are five modules with topics of Formula, Linear and Non Linear Functions, Interest Calculation, Annuity, and Linear Programming. Education expert validation using five aspects resulted in an average score of 4.13 (good). Trial of the teaching materials by measuring student perceptions using three aspects for small groups resulted in an average score of 3.81 (good) and for large groups resulted in an average score of 4.23 (good). Furthermore, results of evaluation in large groups indicate a significant increase in mean of student scores from before and after using computer-based Business Mathematics teaching materials 

Pengembangan Perangkat Pembelajaran Matematika Model Pembelajaran Berbasis Masalah untuk Meningkatkan Kualitas Proses dan Hasil Belajar di SMP

2019 ◽  
Vol 2 (2) ◽  
Author(s):  
Rini Dian Anggraini ◽  
Titi Solfitri
Keyword(s):  
High School ◽  
Small Group ◽  
Junior High School ◽  
Junior High ◽  
Lesson Plan ◽  
Mathematics Learning ◽  
Research Use ◽  
Large Group ◽  
Statistics And Probability ◽  
Group Trial

Penelitian ini bertujuan untuk mengembangkan perangkat pembelajaran matematika untuk sekolah menengah pertama yaitu kurikulum Silabus, Rencana Pembelajaran dan Lembar Kerja Siswa 2013 tentang statistik dan probabilitas dengan menggunakan model pembelajaran berbasis masalah. Penelitian ini menggunakan model pengembangan oleh Borg dan Gall yang dimodifikasi oleh Sugiyono (2008) melalui langkah-langkah: (1) potensi dan masalah; (2) pengumpulan data; (3) desain produk; (4) validasi desain; (5) revisi desain; (6) uji coba kelompok kecil; (7) revisi produk; (8) uji coba kelompok besar; (9) revisi produk. Pada tahap potensi dan masalah, para peneliti melakukan analisis potensi dan masalah. Kemudian, peneliti mengumpulkan data yang diperlukan sebagai referensi untuk desain perangkat pembelajaran matematika yang akan dikembangkan. Desain perangkat pembelajaran yang telah dikembangkan kemudian divalidasi oleh tiga validator dan direvisi berdasarkan saran validator. Hasil perancangan perangkat pembelajaran kemudian diujicobakan dalam uji coba kelompok kecil yang subjeknya 8 siswa kelas VII SMP Negeri 23 Pekanbaru. Setelah dicoba dalam uji coba kelompok kecil, kemudian direvisi berdasarkan kuesioner dari siswa yang mengikuti uji coba kelompok kecil. Setelah itu, para peneliti melakukan uji coba dalam kelompok besar yang subjeknya adalah 39 siswa kelas VII SMP Negeri 23 Pekanbaru, direvisi lagi dan disempurnakan. Berdasarkan hasil analisis dan diskusi data, perangkat pembelajaran yang telah dikembangkan valid yang nilai untuk Silabus adalah 3,39, rata-rata nilai untuk 5 Rencana Pelajaran adalah 3,41. Nilai rata-rata untuk 5 Lembar Kerja Siswa adalah 3,34. Lembar Kerja Siswa yang telah dikembangkan adalah persyaratan praktis yang memenuhi syarat untuk digunakan oleh siswa sekolah menengah pertama.   This research aimed to develop mathematics learning device for junior high school that are Syllabus, Lesson Plan and Students Worksheet curriculum 2013 on statistics and probability by used problem based learning model. This research use development model by Borg and Gall modified by Sugiyono (2008) through the steps : (1) potentials and problems; (2) data collection; (3) design product; (4) validation of design; (5) revision of design; (6) small group trial; (7) revision of product; (8) large group trial; (9) revision of product. At potentials and problems stage, the researchers conducted analysis of potentials and problems. Then, researchers collect the necessary data as reference to design of mathematics learning device that will be developed. Design of learning device that had been developed then validated by three validators and revised based on validator suggestion. The result of learning device design and then try out in small group trial which subjects are 8 students of VII SMP Negeri 23 Pekanbaru. After try out in small group trial, then it revised based on questionnaire from the students who take the small group trial. After that, the researchers conducted try out in large group trial which subjects are 39 students of VII SMP Negeri 23 Pekanbaru, revised again and refined. Based on result of data analysis and discussion, learning device that had been developed is valid which value for Syllabus is 3,39, the average of value for 5 Lesson Plan are 3,41. The average of value for 5 Students Worksheet are 3,34. Students Worksheet that had been developed is qualify practical requirement to used by students of junior high school.

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