A thermodynamic calculation of the electron work function and the composition of the charge component of a saturated vapor has been performed for congruently evaporated alkali metals and Na3AlF6. It has been shown that similar calculations are valid for alkaline-earth metal oxides.

На примере конгруэнтно испаряющихся галогенидов щелочных металлов и Na 3 AlF 6 проведен термодинамический расчет их работ выхода электрона и состава заряженной компоненты насыщенного пара. Показана применимость аналогичных расчетов для оксидов щелочноземельных металлов.

The literature data on equilibrium with the participation of cobalt fluorides and their negative ions are analyzed. Enthalpies of formation −∆fH°(0 K) are determined (kJ/mol): CoF3, 568.9 ± 8; $${\text{CoF}}_{3}^{ - }$$ , 972.4 ± 10; CoF4, 639.4 ± 12; $${\text{CoF}}_{4}^{ - }$$ , 1228.0 ± 17.

The formation enthalpies of crystalline M3AlF6 and gaseous MAlF4 are confirmed and refined and the formation enthalpy of KAlF4(cryst.) is estimated for MF–AlF3 systems (M is Li, Na, or K) with a minimum in the total saturated vapor pressure.

The known first-order orientational phase transition in pure C-60 occurs at 260 K and is accompanied by the change from face-centered cubic (Fm3m) to simple cubic unit cell (Pa (3) over bar). While C-60 molecules rotate freely above 260 K, they are fixed in inversion centers below 260 K. The phase transition in methane-intercalated C-60, (CH4), (C-60), occurs at 236 +/- 2 K. It was studied by DSC and single crystal x-ray diffraction. Above 236 K, the intercalate adopts the face-centered cubic structure which is characterized by freely rotating C-60 and disordered CH4 molecules. The ordered low-temperature crystal structure possesses simple cubic unit cell in the space group Pa (3) over bar in which both C-60 and CH4 molecules are fixed on threefold inversion axes. In the structure of (CH4)(0.72)C-60 at 100 K, a C-60 molecule is fixed by its 12 C-60 neighbors due to donor-acceptor van der Waals interactions between electron-rich 6:6 C-C bonds and electron-deficient cage pentagons. At 200 K, the second orientation of a C-60 molecule is present (with 7.5% occupancy) in which 6:6 C-C bonds are directed to cage hexagons. The methane molecules are situated in octahedral holes and statistically disordered over two orientations around inversion centers. The phase transition temperature of (CH4) C-60 intercalate is lower than in C-60 by similar to 24 K due to the increased C-60 center dot center dot center dot C-60 separation. This study provides a reliable structural information about the low-temperature structure of the (CH4)(0.7)(C-60) intercalate thus demonstrating significant differences between orientational phase transitions in pure fullerite C-60 and C-60 intercalated with methane. In addition, the molecular structure of C-60 fullerene in the (CH4)(0.7)C-60 intercalate is distinguished by a high precision which is superior to the former experimental data for C-60 and its adducts reported in the literature.

ABSTRACT Fluorinated microwave exfoliated graphite oxide (MEGO) samples containing 5.7–29.3 at.% of fluorine were prepared by gas phase treatment of MEGO with XeF2. According to X-ray photoelectron spectroscopy and infrared spectroscopy data, fluorination of MEGO occurs at C=C bonds while leaving the oxygenated domains intact, and increases the O/C ratio. Cyclic voltammetry studies of fluorination effect on double layer capacitance of MEGO shows 67% growth of its specific capacitance, making such and related carbon materials prospective for supercapacitor applications.

The oxidation of C 60 and C 70 fullerites and C 60 /C 70 mixture is accompanied by the decomposition of the carbon frameworks of the molecules at annealing temperatures of 250 and 445°C. Fourier-IR and HPLC studies show that the oxidation/decomposition of C 70 molecules is more active than that of C 60 . The stages of fullerite interaction with oxygen while heating in air were determined.

Fullerite with the bulk formula Ar x C 60 , where 0.60 < x < 0.75, was synthesized by precipitation from a mixture of argon-saturated solutions. The fcc unit cell parameter in the sample was 1.422 nm; the orientational phase transition (OPT) temperature was 247 K. These values noticeably differ from the relevant parameters of undoped fullerite (1.416 nm and 260 K, respectively). Heating accompanied by argon evolution restores the fullerite C 60 structure.

Powder X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, and molecular dynamics have been employed to investigate structural transformations in hexagonal and cubic modifications of fullerite C 60 after the action of high pressure (4 GPa) within the temperature range 20–1450°C. It has been found that fullerene molecules polymerize to afford polymer structures only in the case of face-centered cubic samples. Under the effect of high pressure and temperature, fullerite C 60 with a hexagonal close-packed structure is initially transformed into the cubic modification and, then, forms polymerized structures, which, during an increase in the treatment temperature, become less stable and ordered than the same polymerized structures obtained directly from cubic fullerite C 60 . X-ray photoelectron spectroscopy measurements suggest deformation of the cages of fullerene molecules in the polymerized structures.

s189(Grenoble) (λ=0.3748Å) at 25 o and 250 o C, respectively, suggests that the coefficient of thermal expansion is highest for samples with low iron substitution.Split of triangular Cu2 positions increases with temperature and the halfoccupied Cu2 positions from different coordination triangles approach one another, down to 2.70-2.75Å in tennantite at 250 o C.There is insignificant residual electron density between the split Cu2 half-sites in tetrahedrite at 25 o C and its increase with temperature is moderate.The inter-site density is substantially higher in tennantite and it increases considerably with temperature, especially in the low-Fe sample.