摘要:

The possibility of the high spin stable states in the Boron-Carbon layered network systems have theoretically investigated through several BC 6MR polyacene clusters. The HF/6–31G** calculations reveal that the alternant BC-benzene gives a quartet stable state rather than a doublet one, while a doublet state is more stable for the non-alternant BC-benzenes. Similarly, alternant BC-naphthalene gives a high-spin stable state (sextet) rather than lower ones (doublet, or quartet). These features are well understood by extending the Longuet-Higgins [1] theory to this BC system.

ISSN:1058-725X    

DOI:10.1080/10587250008025453

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Platinum chloride-graphite intercalation compounds (PtCl4-GICs) were synthesized from platinum chloride (PtCl4) and graphite under pressurized chlorine atmosphere. The analysis of XRD patterns showed that platinum chloride was inserted into graphite layers and the PtCI4-GICs with a stage 3 structure were formed. The curve-fitting analysis of Pt LIII-edge EXAFS showed that the distance of the Pt-Cl-Pt bond of 5 wt% PtCl4-GIC was 0.06 A longer than that of the PtCl4bulk, indicating that PtCl4had a distorted structure in graphite layers. PtCl4samples were reduced in hydrogen atmosphere to produce platinum metal particles in graphite layers. EXAFS analysis showed that the coordination numbers of Pt-Pt metal bond for PtCl4-GIC samples reduced at various temperatures were lower than those of the mixture of PtCl4and graphite (PtCl4-Gmix) samples reduced in the same manners.

ISSN:1058-725X    

DOI:10.1080/10587250008025454

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The behaviour of 2–4 stages graphite nitrate in different mediums: H2O, CH3COOH and their mixtures was analysed by potentiometry, calorimetry and X-ray on highly oriented pyrolytic graphite. The intercalation of 75–98.6% HNO3into dispersible graphite at the different mass ratio of reagents, and the influence of chemical treatment of graphite nitrate by CH3COOH solutions on properties of hydrolyzed samples (oxidized graphite) were studied.

ISSN:1058-725X    

DOI:10.1080/10587250008025455

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The interaction of highly oriented pyrolytic graphite with nitric acid in a wide range of its concentrations was studied by potentiometry and X-ray. The threshold values of HNO3concentration for the different stages of graphite nitrate formation have been determined during spontaneous and electrochemical intercalation. At anodic oxidation of graphite in 55–98% HNO3the typical step-like character of the dependence of potential E(Q) is observed. The polarization of graphite (I=100μA) in 55–98% HNO3results in obtaining the 2nd stage graphite nitrate. The increase of a current intensity (I) up to 1.5 mA allows to carry out synthesis of the 1st stage in 75–98% HNO3.

ISSN:1058-725X    

DOI:10.1080/10587250008025456

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

c-axis thermoelectric power (TEP)Scof stage-2 graphite intercalation compound with iodine monobromide (IBr-GIC) was measured below the room temperature, and the calculation was carried out by our theory. The major part ofSccomes from the diffusion TEPSc-d. However, a slight deviation exists betweenSc-dand the experimental resultScand it can be removed in consideration of phonon drag TEPSc-p. This situation was different from the case of graphite intercalation compound with iodine monochrolide (ICI-GICs). Above the room temperature, we attempted to measure the TEP of stage-2 IBr-GIC. It shows the phase transition similar to the case in ICI-GICs.

ISSN:1058-725X    

DOI:10.1080/10587250008025457

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A new model for the charge transfer mechanism and electronic states of the acceptor-type graphite intercalation compounds is proposed. The essential points of this model are the following two. One is the transformation of the molecular intercalate into another molecular form with the open shell electronic state. The other is the existence of the Fermi surface originated in the intercalate due to the incomplete charge transfer to its singly occupied molecular orbital.

ISSN:1058-725X    

DOI:10.1080/10587250008025458

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The paper deals with the synthesis, structure and electrochemical properties of CrO3-H2SO4-graphite bi-intercalation compound (CrO3-H2SO4-GBC) prepared at room temperature. In contrast to the two step process in which CrO3is first intercalated chemically followed by electrochemical bi-intercalation of H2SO4, the method described in the paper allows the simultaneous intercalation of CrO3and H2SO4into graphite to give CrO3-H2SO4-GBC. The electrochemical method appeared to be suitable both to distinguish the original CrO3-H2SO4-GBCs of different structures and to enrich them with H2SO4to provide stage-1 compound.

ISSN:1058-725X    

DOI:10.1080/10587250008025459

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

FeCl3-CrO3-graphite bi-intercalation compound (FeCl3-CrO3-GBC) encompassing the double FeCl3-CrO3co-intercalation layers was examined by FTIR spectroscopy and thermal analysis. The results obtained for FeCl3-CrO3-GBC were compared to those for the binary graphite intercalation compounds: FeCl3-GIC and CrO3-GIC. In FTIR spectrum for FeCl3-CrO3-GBC the bands observed in both FeCl3-GIC and CrO3-GIC were preserved with a slight shifting and new band around 1100–1200 cm−1appeared. The reason for this feature is suggested to arise from the donor-acceptor interaction within FeCl3-CrO3-graphite system. Such an explanation is consistent with TG, DSC and XRD measurements.

ISSN:1058-725X    

DOI:10.1080/10587250008025460

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

BxC1−xhost materials (0.1 < × < 0.25) and their intercalation compounds with heavy alkali metals prepared from the vapor reaction or from the reaction of cesium in ammonia solution were characterized using13C and11B NMR and EPR.13C NMR shifts and EPR dysonian lines (typical of conductors) found in intercalation compounds are qualitatively similar to those observed in their GIC analogues. Evidence are reported in favor of a breaking of the local axial symmetry due to interstitial boron atoms for highest × values and partial recover of this symmetry in the intercalation compounds.

ISSN:1058-725X    

DOI:10.1080/10587250008025461

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

FeCl3-IBr, -ICI, and -SbCl5-graphite bi-intercalation compounds (GBC's) have been synthesized from a stage 4 FeCI3-graphite intercalation compound (GIC). and their lattice dynamics has been investigated by Raman spectroscopy. First, layer sequences of these GBC's were determined by x-ray diffraction, and the sequence was determined to be G(FeCl3)G1G2(1)G3G4(FeCI3)G. where Gn, (FeCl3), and (1) refer to thenth graphite, FeCl3, and bi-intercalate layers, respectively. The sequences were the same irrespective of bi-intercalated species. These GBC's give only one peak identified as Raman active mode frequency in the Raman spectra. The peak frequencies were found to be affected by bi-intercalated species, and the frequencies were in the order of IBr <ICI <SbCl5. From this result, the degree of charge transfer was determined to be in the order of IBr < ICI < SbCl5.

ISSN:1058-725X    

DOI:10.1080/10587250008025462

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor