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71.
A. A. Pronin S. V. Demishev N. E. Sluchanko N. A. Samarin D. V. Konarev R. N. Lyubobskaya 《Physics of the Solid State》2000,42(3):586-588
The permittivity ? of the molecular complexes (BTX)C60CS2, (DAN)C60(C6H6)3, and (S4N4)1.2C60(C6H6)0.8 has been studied at 100 MHz. A maximum has been observed to appear in the temperature dependence ?(T) at T≈90 K, which can be assigned to freezing of the orientational disorder. A region of anomalous growth of ? with decreasing temperature has been found in the low-temperature range T≤25 K, this feature being apparently sensitive to the actual packing pattern of C60 spheres in the molecular complex. 相似文献
72.
Crystallography Reports - According to the diffraction tomography data, the efficiency of minimization algorithms used to reconstruct the displacement field of a defect in a crystal depends on the... 相似文献
73.
Petukhov M. V. Konarev P. V. Dadinova L. A. Fedorova N. V. Volynsky P. E. Svergun D. I. Batishchev O. V. Shtykova E. V. 《Crystallography Reports》2020,65(2):258-263
Crystallography Reports - Small-angle X-ray scattering is an important structural tool for studying biological membranes; however, interpretation of scattering data remains a challenging problem.... 相似文献
74.
JETP Letters - To analyze polydisperse systems of nanoparticles, the particle size distribution function can be determined from small-angle X-ray and neutron scattering data using some algorithms.... 相似文献
75.
The temperature dependence of the x-ray absorption spectra above the L
3 absorption edge of bismuth in the superconducting oxide Ba0.6K0.4BiO3 are investigated. It is found that the local structure is different from the simple cubic structure indicated by x-ray and
neutron-diffraction data. It is shown that the oxygen atoms move in an anharmonic double-well potential arising as a result
of the existence of two nonequivalent types of octahedral environments of bismuth. Vibrations in such potential modulate the
Bi-O bond lengths at the low frequency of the rotational (“tilting” type) mode of the oxygen octahedra and thus give rise
to a strong electron-phonon interaction, which explains the quite high superconducting transition temperatures T
c
∼30 K.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 12, 977–982 (25 June 1998) 相似文献
76.
Coordination assemblies of metal tetraphenylporphyrins, MIITPP2.DMP (M=Mn, Zn) were shown to form ionic multicomponent and neutral complexes with fullerene, {(MnIITPP)2.DMP}.(C60-)2.(DMETEP+)2.(C6H4Cl2)5 (1) and {(ZnTPP)2.DMP}.(C60)2.(C6H5Cl)4 (2), where DMP=N,N'-dimethylpiperazine and DMETEP+=the cation of N,N'-dimethyl-N'-ethylthioethylpiperazine. The crystal structure of 1 contains zigzag chains of the (C60-)2 dimers alternating with the DMETEP+ cations in the channels formed by the (MnIITPP)2.DMP units, whereas in 2 zigzag chains of the C60 molecules are separated by the (ZnTPP)2.DMP units and C6H5Cl molecules. The (MIITPP)2.DMP assemblies (M=Mn, Zn) have axial M-N(DMP) bonds of 2.315(2) and 2.250(2) A length, average equatorial M-N(DMP) bonds elongated to 2.141(3) and 2.077(2) A, and MII atoms displaced from the porphyrin plane toward the ligand by 0.677 and 0.485 A, respectively. The single-bonded sigma-(C60-)2 dimer coexists in 1 with the (C60-)2 dimer bonded by two single bonds with 86/14 occupancy factors. The sigma-(C60-)2 dimers are unusually stable and begin to dissociate only above a temperature of 320-330 K that results in the increase of the magnetic moment of 1 from 8.33 microB (320 K) to 8.66 microB (360 K). The electron paramagnetic resonance (EPR) signal of the dimeric phase (T<320 K) with the features spread over the range of 0-0.7 T was attributed to the interacting Mn2+ centers in the (MnIITPP)2.DMP units. The dissociation of the sigma-(C60-)2 dimers to the EPR-active C60*- radical anions manifests a new broad Lorenz signal above 320 K with g=2.0179 and DeltaH=65.5 mT. This signal can appear due to the exchange coupling between paramagnetic (MnIITPP)2.DMP and C60*- species. The vis-NIR spectrum of the sigma-(C60-)2 dimers is discussed. 相似文献
77.
Strong Antiferromagnetic Coupling of Spins in the (MDABCO+)(C60.−) Salt with 3D Close Packing of the C60.− Radical Anions (MDABCO+: N‐Methyldiazabicyclooctanium Cation) 下载免费PDF全文
Dr. Dmitri V. Konarev Dr. Salavat S. Khasanov Dr. Akihiro Otsuka Prof. Hideki Yamochi Prof. Gunzi Saito Prof. Rimma N. Lyubovskaya 《化学:亚洲杂志》2014,9(6):1629-1635
A new salt, (MDABCO+)(C60.?) ( 1 ; MDABCO+=N‐methyldiazabicyclooctanium cation), was obtained as single crystals. The crystal structure of 1 determined at 250 and 100 K showed 3D close packing of fullerenes with eight fullerene neighbors for each C60.?. These neighbors are located at 10.01–10.11 Å center‐to‐center distances (250 K) and van der Waals interfullerene C???C contacts are formed with four fullerene neighbors arranged in the bc plane. Fullerene ordering observed below 160 K is accompanied by the appearance of one and a half independent C60.? and trebling of the unit cell along the b axis. Fullerenes are packed closer to each other at 100 K. As a result, fullerenes are located in the three‐dimensional packing at 9.91–10.12 Å center‐to‐center distances and 18 short interfullerene C???C contacts are formed for each C60.?. Although they are closed packed, fullerenes are not dimerized down to 1.9 K. Magnetic data indicate strong antiferromagnetic coupling of spins in the 70–300 K range with a Weiss temperature of Θ=?118 K. Magnetic susceptibility shows a round maximum at 46 K. Such behavior can be described well by the Heisenberg model for square two‐dimensional antiferromagnetic coupling of spins with an exchange interaction of J/kB=?25.3 K. This magnetic coupling is one of the strongest observed for C60.? salts. 相似文献
78.
Metallic and Mott Insulating Spin‐Frustrated Antiferromagnetic States in Ionic Fullerene Complexes with a Two‐Dimensional Hexagonal C60.− Packing Motif 下载免费PDF全文
Dr. Dmitri V. Konarev Dr. Salavat S. Khasanov Dr. Akihiro Otsuka Dr. Mitsuhiko Maesato Dr. Mikio Uruichi Dr. Kyuya Yakushi Dr. Artem F. Shevchun Prof. Dr. Hideki Yamochi Prof. Dr. Gunzi Saito Prof. Rimma N. Lyubovskaya 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(24):7268-7277
(MDABCO+)(C60.?)(TPC) ( 1 ), in which MDABCO+ is N‐methyldiazabicyclooctanium, TPC is triptycene, and both have threefold symmetry, is a rare example of a fullerene‐based quasi‐2D metal and contains closely packed hexagonal fullerene layers with interfullerene center‐to‐center distances of 10.07 Å at 300 K. Evidence for the metallic nature of 1 was obtained by optical and microwave conductivity measurements on single crystals. The metal is characterized by a nontypical Drude response and relatively large optical mass (m*/m0=6.7). The latter indicates a narrow‐band nature, which is consistent with the calculated bandwidth of 0.10–0.15 eV. The coexistence of metallic and antiferromagnetic nonmetallic 2D layers was observed in 1 above 200–230 K. It was assumed that the nonmetallic layers undergo a transition to the metallic state below 200 K due to ordering of the fullerene and cationic sublattices. New layered complex (MQ+)(C60.?)(TPC) ( 2 ) with a hexagonal arrangement of C60.? was obtained by increasing the interfullerene distance with the bulkier N‐methylquinuclidinium cations (MQ+) having threefold symmetry. The structure of 2 is characterized by increased interfullerene center‐to‐center distances in the layers (10.124, 10.155, and 10.177 Å at 250 K). Unit‐cell doubling parallel to the 2D layer (along the b axis) was observed at low temperatures. In contrast to metallic 1 , 2 exhibits a nonmetallic spin‐frustrated state with an antiferromagnetic interaction of spins (the Weiss temperature is ?27 K) and no magnetic ordering down to 1.9 K. It was supposed that the expanded interfullerene distances in the triangular arrangement decrease the bandwidth and suppress metallic conductivity in 2 , and thus a Mott–Hubbard insulating state with antiferromagnetically frustrated spins results. 相似文献
79.
Konarev DV Khasanov SS Otsuka A Saito G Lyubovskaya RN 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(20):5225-5230
Ionic multicomponent complexes containing the C60- anion, cobalt(II) octaethylporphyrin (OEP), and the noncoordinating tetramethylphosphonium cation (TMP+), [(TMP+){Co(II)OEP(C60-)}(C6H5CN)x(C6H4Cl2)(1-x)] (x congruent with 0.75) (1), or the coordinating cation of N-methyldiazabicyclooctane (MDABCO+), [{(MDABCO+)Co(II)OEP(C60-)}(C6H5CN)x(C6H4Cl2)(1-x)] (x congruent with 0.67) (2), were obtained. Diamagnetic sigma-bonded {Co(II)OEP(C60-)} units in 1 have the Co...C(C60-) distance of 2.268(1) A at 100 K and are stable up to 290 K. Both MDABCO+ and C60- coordinate to Co(II)OEP in 2. In this case, a noticeably longer Co...CC60-) distance of 2.508(4) A was observed at 100 K. As a result, the unprecedented reversible formation of the Co-C(C60-) coordination sigma bond is realized in 2 and is accompanied by a transition from a paramagnetic to a diamagnetic state in the 50-250 K range. It was shown, for the first time, that the Co...C distance of about 2.51 A is a boundary distance below which the Co-C(C60-) coordination bond is formed. 相似文献
80.
Synthesis,Structure, and Properties of the Fullerene C60 Salt of Crystal Violet, (CV+)(C60.−)⋅0.5 C6H4Cl2, which Contained Closely Packed Zigzagged C60.− Chains 下载免费PDF全文
Dr. Dmitri V. Konarev Dr. Alexey V. Kuzmin Dr. Salavat S. Khasanov Dr. Manabu Ishikawa Dr. Akihiro Otsuka Prof. Hideki Yamochi Prof. Dr. Gunzi Saito Prof. Rimma N. Lyubovskaya 《化学:亚洲杂志》2016,11(11):1705-1710
The reduction of fullerene C60 by zinc dust in the presence of crystal violet cations (CV+) yielded a deep‐blue solution, from which crystals of (CV+)(C60.?) ? 0.5 C6H4Cl2 ( 1 ) were obtained by slow mixing with n‐hexane. The salt contained isolated, closely packed zigzagged chains that were composed of C60.? radical anions with a uniform interfullerene center‐to‐center distance of 9.98 Å. In spite of the close proximity of the fullerenes, they did not dimerize, owing to spatial separation by the phenyl substituents of CV+. The room‐temperature conductivity of compound 1 was 3×10?2 S cm?1 along the fullerene chains. The salt exhibited semiconducting behavior, with an activation energy of Ea=167 meV. Spins localized on C60.? were antiferromagnetically coupled within the fullerene chains, with a Weiss temperature of ?19 K without long‐range magnetic ordering down to 1.9 K. 相似文献