摘要:

Graphite intercalation compounds (GICs) with the trichlorides of Y, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu have been prepared and characterized by chemical analysis and X-ray diffraction. Attempts to synthesize binary GICs with LaCl3, CeCl3, PrCl3, and NdCl3failed. By heating mixtures of YCl3+ LnCl3(Ln = La - Lu) with graphite ternary GICs were obtained. The molar ratios LnCl3:YCl3in the GICs were found to increase from La to Dy which runs parallel to the decrease in the ionic radii of the Ln3+ions.

ISSN:1058-725X    

DOI:10.1080/10587259808045317

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The structural properties of second and third stage of graphite intercalation compounds graphite-EuCl3have been studied using x-ray diffraction. The c-axis repeat distances of second and third stage are 13.11 ± 0.07 Å and 16.48 ± 0.06 Å respectively. The EuCl3intercalate layer forms a three-layer sandwich of Cl-Eu-Cl with the structure to that of YC13type.

ISSN:1058-725X    

DOI:10.1080/10587259808045318

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The action of MCl2-AlCl3molten salt systems (M˭Cu, Cd, Pd, Co) does not permit the intercalation into graphite the heteromolecules MAl2Cl8which exist in the liquid. All these molten chloroaluminate reagents give intercalated species which correspond to an AlCl3layer with low divalent ionic content the basal plane structure of which appears to be dependent on the divalent metal. In the case of copper, palladium and cobalt, this 2D order corresponds to a hexagonal cell (a=600pm) whose study based on the experimental and calculated (hko) intensities suggests a substitutional process between the Al3+and M2+ions in the intercalated layers.

ISSN:1058-725X    

DOI:10.1080/10587259808045319

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The temperature dependence of the thermal expansion coefficient α in highly oriented pyrolytic graphite (HOPG), first stage graphite intercalation compound (GIC) C8.1ICl1.1, second stage GIC C16.3ICl1.1, hetero-intercalated compounds C12FeCl3(ICl)0.75and C10CuCl2(ICl)0.6in the main crystallographic directions in the temperature range 40<T<350 K has been investigated. It was shown that the Debye temperatures in plane and in the perpendicular direction are different in ICl graphite intercalation compounds.

ISSN:1058-725X    

DOI:10.1080/10587259808045320

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Physisorption of molecular N2in the 2nd stage CsC24was studied as a junction of temperature and pressure using neutron diffraction The new structures resulting from reaction were determined from the analysis of the 001 lines and they were related to the intercalation rate of N2

ISSN:1058-725X    

DOI:10.1080/10587259808045321

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Using neutron diffraction, a second stage physintercalation of molecular N2into C24Rb has been observed in which the N2molecules reside inside everysecondRb layer. The new phase, C48Rb2(N2)x, coexists below 175 K with pure C24Rb and the 1st stage C24Rb(N2)x. The tilt of the N2molecular axes relative to the graphene planes was determined versus T using the nuclear resonance photon scattering (NRPS) technique and found to be almost parallel to the graphene planes of the C24Rb sample.

ISSN:1058-725X    

DOI:10.1080/10587259808045322

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The intercalation of fluorine into graphite leads to graphite intercalation compounds (F-GICs) exhibiting potential properties such as the storage and transport of fluorine. Stage-1 compounds with C2.5F to C4F compositions are obtained by fluorination treatments at room temperature of ex-pitch, high-temperature treated carbon fibres under 10 bars F2pressure in the presence of gaseous HF. The deintercalation process of fluorine species has been studied by evolved gas analysis: the F-GICs are decomposed using the Controlled transformation Rate Thermal Analysis (CRTA) method. The thermal analysis curve obtained for stage-1 F-GICs exhibits three decomposition steps. The first two steps correspond to a simultaneous deintercalation of atomic fluorine F and gaseous HF and the third step (above 460°C) to the degradation of the compound with formation of C2F4and CF4which further dissociate in the spectrometer to CFn(1 ≤ n ≤ 3) species.

ISSN:1058-725X    

DOI:10.1080/10587259808045323

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The possible formation of a fcc Cs3C60phase which should have a high critical temperature is critically reviewed. Temptative synthesis of this derivative has been realized by playing on the kind of defects present in solid C60and also by reacting C60either with cesium vapor or with cesium dissolved in liquid ammonia. Whatever the experimental conditions, the fcc phase was never formed. Moreover, we could not observe the formation of bcc Cs3C60. Opposite to many statments, temperature does not modify drastically the nature of the phases formed, and even heat treatment up to 750°C leads, after cooling down, to a mixture of A15 and bct phases, whatever the method of preparation.

ISSN:1058-725X    

DOI:10.1080/10587259808045324

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

C60fullerene was converted with IBr as well as ICl. Two methods of preparation were used: Either the molten interhalogen compound was mixed up with C60, or C60was exposed to the vapour phase of the interhalogen compounds. After removing excess IBr or ICl respectively by gentle warming, the reaction products were ascertained to have the compositions C60(IBr)2.6and C60(ICl)3.2X-ray diffraction and Raman spectroscopy proved these compounds to be intercalation compounds. However besides intercalation, part of the C60balls were found to undergo halogenization or dimerization. EPR spectra show two singlet lines corresponding to the C60+radical cation and a paramagnetic partially negatively charged interhalogen species. The C60+signal is comparatively broad, indicating a strong coupling between paramagnetic centers.

ISSN:1058-725X    

DOI:10.1080/10587259808045325

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Syntheses of new inorganic fluorides - fullerenes compounds with IrF6, NbF5and TaF5were investigated. X-ray diffraction, IR and NMR measurements revealed the presence of anionic and reduced fluoride species. Some reactions with NbF5, TaF5, TiF4were performed under chlorine atmosphere as a result of which chlorinated compounds were obtained.

ISSN:1058-725X    

DOI:10.1080/10587259808045326

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor