Authors:Xian'e Cia, Daichun Du, Youming Jin, and Yixiang Qian
N(C5F11)3 (Fluorint FC-70) has been chosen as the test material to compare the chemicophysical data obtained by static-sample and DSC
The normal boiling point, the molar enthalpy of vaporization, and the constants of the Antoine equation of fluorint FC-70
DSC can be developed into a simple and rapid routine instrument to determine the enthalpy of vaporization as well as the boiling
point of liquid, particularly at relative high temperature.
A CO2-laser cw system and a photoacoustic detection apparatus, based on a nonresonant gas cell, was constructed and built. Coincidences of D2O absorption with several laser lines were observed. The strongest absorption was observed with the line at 9.26 m, which was used in the experiments. Samples of deuterated water in the range from 10 to 100% deuterium were used to examine the behaviour of the photoacoustic signal under conditions of varying deuterium content and total vapour pressure. A principal calibration procedure with respect to this is proposed. The behaviour of the system on buffer gas introduction was examined with hydrogen and dry air. Self-buffering of water vapour is also discussed on the basis of the results.
Recent experiments are reviewed which used on-line isothermal gas chromatography techniques for studying chemical properties of transactinide elements. In these experiments the volatilities of chloride and bromide molecules in quartz columns were investigated. Measured chromatograms obtained with single molecules are shown to be correlated with the vapor pressure of the corresponding macroamounts. All existing data reveal that element 104 (rutherfordium) chloride has a volatility resembling very much those of the chlorides from the homologous elements hafnium and zirconium. For element 105 (hahnium) a surprisingly low volatility of the bromide compound, is found if compared to those of the corresponding bromides from the homologous elements tantalum and niobium. This latter experimental observation contrasts relativistic theoretical calculations which would predict a higher volatility for hahnium bromide if compared to those of tantalum and niobium bromides.
Authors:S. Sysoev, T. Cheremisina, L. Zelenina, S. Tkachev, K. Zherikova, N. Morozova, and N. Kuratieva
The comprehensive analysis of volatile β-diketonate compound—ruthenium(III) trifruoroacetylacetonate (Ru(tfac)3)—was carried out. By means of flow method in quasi-equilibrium conditions and static method the temperature dependencies
of saturated vapor pressure have been measured over solid and liquid cis- and trans-modifications of Ru(tfac)3 and isomer mixture. The thermodynamic characteristics of sublimation, evaporation, melting, and phase conversion have been
calculated for structural isomers. Also by differential-scanning calorimetry the temperature meanings and the thermodynamic
characteristics of melting have been determined for individual isomers of Ru(tfac)3 and their mixtures. By XRD the structures for cis- and trans-modifications have been determined. Both structures consist of neutral molecules arranged in pseudo layers.
E37 on Thermal Measurements published a new test method 'Standard Test
Method for Volatility Rate by Thermogravimetry' in June 1999 with the
designation E 2008. This approach to assessing volatility utilizes an extension
of the pinhole technology previously employed by E37 for vapor pressure determinations
using differential scanning calorimetry (ASTM E 1782). After publication of
the test method E 2008, an Interlaboratory Study was undertaken to develop
a 'Precision and Bias' statement to be assigned with the test
method. This paper provides some background data that supports the claim that
E 2008 is generally insensitive to experimental conditions other than temperature.
The Interlaboratory Study showing the statistical review is also discussed.
A differential microcalorimeter (E. Calvet) was used to study the processes of adsorption of five aliphatic alcohols (C1-C5) on α-Al2O3 at 25, 50, 100, 150 and 200°C. In particular, the importance of the thermokinetic study of the chemisorption of such alcohols
at different experimental temperatures was demonstrated, with regard to the variations in the thermokinetic parameters (tmax, t1/2 and t0) and the evolution of the alcohol vapor pressure on the adsorbent during the adsorption process. It was concluded that:
all the heat emission peaks of alcohol adsorption have the same rounded shape at 25°C;
on passing from methanol to 1-pentanol, the area of the adsorption peaks increases as the chain length or molecular weight
on passing from 25 to 200°C, the shape of the adsorption peaks becomes more pointed.
The present article describes the synthesis, spectral, coordination and thermal aspects of N,N′-polymethylene bis(1-phenyl-3-methyl-4-trifluoroacetylimino-2-pyrazoline-5-ol)oxovanadium(IV) or copper(II) Schiff base complexes with alkyl
backbones ranging from two to four carbons have been characterized on the basis of elemental analysis, magnetic moments, molar
conductivity measurements, spectra (FTIR, ESR, UV-Visible, MS), VPO and thermal studies. The vapour pressure osmometry (VPO)
and mass spectral studies indicate that the complexes are monomeric. An ESR study of all these complexes of VO(IV) and Cu(II)
are consistent with the square pyramidal and square planar geometries of these metal ions, respectively. In addition, the
kinetics and thermodynamic parameters for the different thermal decomposition steps of the complexes have been studied employing
Horowitz-Metzger and Freemen-Carroll methods.
Elementary thermochemical calculations show that in all cases of formation of solid product in the process of the congruent
dissociative vaporization of reactants, the equilibrium partial pressure of the main product greatly exceeds its saturation
vapour pressure, and therefore causes the appearance of vapour oversaturation. The oversaturation is responsible for the formation
and growth of nuclei, their shape and position, the transfer of condensation energy to the reactant, the existence of induction
and acceleration decomposition periods, the reaction localization, the epitaxial/topotaxy effects and the nanocrystal structure
of the solid product. Variations in the energy transfer explain an increase of the molar enthalpy with temperature and the
decelerating influence of melting on the rate of decomposition.
Authors:M. Suşeska, M. Rajiş, S. Matečiş-Mušaniş, S. Zeman, and Z. Jalový
TNAZ (1,3,3-trinitroazetidine) is a relatively new, powerful, steam castable, strained ring explosive. Owing these characteristics
it is of considerable interest to the energetic material community. A relatively high vapour pressure, volume contraction
and formation of shrinkage cavities in the solidification of its melt may be considered as some of its disadvantages. The
kinetics and heats of TNAZ sublimation and evaporation were studied by the non-isothermal and isothermal thermogravimetry
method. The activation energy of 94-102 kJ mol-1 was found for TNAZ sublimation, while the activation energy of 60-81 kJ mol-1 was found for TNAZ evaporation. The enthalpy of TNAZ sublimation at the melting temperature was found to be 95 kJ mol-1, and the enthalpy of TNAZ evaporation equals 66 kJ mol-1.
Authors:G. Golan, A. Axelevitch, B. Sigalov, and B. Gorenstein
Thermal effects in a low-pressure plane plasma discharge were obtained in a novel implementation of triode sputtering method.
This plane plasma discharge is formed in a relatively low vapor pressure of 0.03-0.65 Pa. Electron beam temperature and ion
beam concentration distribution, as well as their dependence on argon pressure within the plasma, were experimentally studied,
using the Langmuir probe technique. The influence of an external magnetic field on the ion beam concentration, and electron
beam temperature, were studied too. As a result of these studies, sputtering of various materials was done using the novel
plane plasma discharge method. This method enables the deposition of homogeneous thin film coatings. Analysis is done on Cu
sputtered layers with plane plasma discharge.