Thermodynamic properties of gaseous niobium chlorides

Keneshea, F. J.; Cubicciotti, Daniel

doi:10.1021/j100843a046

Cited by 5 publications

(2 citation statements)

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“…Above 345 K, the high-temperature heat capacities derived from equations (1), (2), (3) and (4) were used. 50 The thermodynamic functions appear in Table 4 (joules) and Table 5 (calories). In Table 6 are given selected values of the thermodynamic functions which resulted from a preliminary smoothing and integration;…”

Section: Thermodynamic Functions Of Bariummentioning

confidence: 99%

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Interim report on the thermodynamics of chemical species important to rocket technology

1970

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FOREWORD Structure, propulsion, and guidance of new or improved weapons delivery systems are dependent in crucial areas of design on the availability of accurate thermodynamic data.Data on high-temperature materials, new rocket propellant ingredients, and combustion products (including exhaust ions) are, in many cases, lacking or unreliable.This broad integrated research program at the National Bureau of Standards supplies new or more reliable thermodynamic properties essen¬ tial in several major phases of current propulsion development and application. Measured are compounds of those several chemical elements important in efficient propulsion fuels; those substances most affecting ion concentrations in such advanced propulsion concepts as ion propulsion; and the transition and other refractory metals (and their pertinent compounds) which may be suitable as construction materials for rocket motors, rocket nozzles, and nose cones that will be durable under extreme conditions of high temperature and corrosive environment.The properties determined extend in temperature up to 6000 degrees Kelvin.The principal research activities are experimental, and involve developing new measurement techniques and apparatus, as well as measur¬ ing heats of reaction, of fusion, and of vaporization; specific heats; equi¬ libria involving gases; fast processes at very high temperatures; spectra of the infrared, matrix-isolation, microwave, and electronic types; and mass spectra.Some of these techniques, by relating thermodynamic properties to molecular or crystal structures, make it possible to tabulate reliably these properties over far wider ranges of temperature and pressure than those actually employed in the basic investigations. ABSTRACTThis report presents in detail the results and critical analyses of several recently completed NBS experimental investigations, literature surveys, and de¬ velopments of new measurement methods.The heat of formation of C£F was measured by burning it with 1^ in a flame calorimeter; the result is shown to favor the new lower dissociation energy of Y32.0 kcal per mol, but not unambiguously owing to uncertain interpretations of necessary auxiliary data.A transpiration search for chemical reaction between HF and gaseous A£F^ revealed none detectable, near 1200 K and up to 0.75 atm of HF, beyond the sensitivity of the method (1-2%). Selected values of the standard heats, free energies, and entropies of formation of a number of niobium compounds resulting from an up-to-date critical review of the literature are discussed and tabulated.The heat capacity, electrical resistivity, and hemispherical total and normal spectral emittances of tantalum metal were measured by an accurate high-speed pulse technique from 1900 to 3200 K; the spectral emittance (at a wavelength of 650 nm) was found to decrease approxi¬ mately 3.5% during the initial one-third of the melting period.The pulse heating technique is adapted to measuring the melting points of thin-wire electrical con¬ ductors above 2000 K, and checked by fi...

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Section: Thermodynamic Functions Of Bariummentioning

confidence: 99%

“…NbCl4(g), NbCl3(g) Addition A study of the equilibria of Nb(s) and NbCl^Cg) in the tempera¬ ture range 1100-1700 K by transpiration measurements and mass spectro¬ metry made by Kenshea and Cubiciotti [50] was called to our attention after the previous analysis was completed.…”

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confidence: 99%