The atomic heats of titanium, zirconium and hafnium

Wolcott, N. M.

doi:10.1080/14786435708244013

Cited by 46 publications

(9 citation statements)

References 14 publications

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“…By measuring the normal vibrational modes of GVDS of a system one can provide information regarding the temperature dependence of its thermophysical properties. Complex investigations combining calorimetric measurements [21] or INS techniques [22] have been performed only for metallic zirconium. Moreover, no complete data about the corresponding Debye characteristic temperature q D and its temperature dependence have been published for hydrides or deuterides of zirconium.…”

Section: Introductionmentioning

confidence: 99%

On the High-Frequency Limit of Lattice Vibrations in Zirconium Hydrides and Deuterides

Rădulescu

Padureanu

Rapeanu

et al. 2000

phys. stat. sol. (b)

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Section: Introductionmentioning

confidence: 99%

On the High-Frequency Limit of Lattice Vibrations in Zirconium Hydrides and Deuterides

Rădulescu

Padureanu

Rapeanu

et al. 2000

phys. stat. sol. (b)

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“…Transmission measurements with a double-pinhole 3 cm-path cell were made, to obtain the total cross section. The observed Debye temperatures, 420 _+ 9 °K for Ni and 240 _+ 6 °K for Hf, possess larger uncertainties than the calorimetric values, 440 °K for Ni (Rayne & Kemp, 1956) and 260 °K for Hf (Wolcott, 1957). Subsequently, the latter values were chosen and low-angle reflections were employed for the coherent intensity measurement.…”

Section: January 1964)mentioning

confidence: 99%

Slow-neutron cross sections of hafnium

Atoji¹

1964

Acta Cryst

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The slow-neutron scattering and related cross sections of hafnium pertinent to neutron diffraction study are the major subject of this paper. Nearly two dozen publications have dealt with cross sections of hafnium, since, apart from control and poison applications in nuclear reactors, the proton-neutron number correlation in hafnium isotopes provides an attractive subject for nuclear energy level studies. However, inconsistencies between the observed cross sections and those computed from the Breit-~¥igner dispersion formula suggest further study on the topic (see Itkin, 1962, for reference summary).The cross sections of naturally occurring hafnium at 293 -+3 °K have been re-examined at 0.0717 -+0.0002 eV (4 = 1.068 _+ ().002 A) and some at 0.0460 eV (/t = 1.333 /~) using a newly constructed neutron diffractometer (Atoji, 1964). The standard deviations cited for our experimental values are obtained from not less than six independent observations. No suitable hafnium compound with reliable composition and structural parameters was available. Consequently, the absolute intensities of hafnium metal filings, with nickel powder as standard, were measured based on the method of substitution and that of mixtures. Lack of sufficient impurity analysis apparently interfered with some of the earlier cross section values. The hafnium metal used in the present work was 99-13 wt. % pure, and was subjected to three independent spectroscopic analyses, which revealed, as major impurities, zirconium 8000 ppm, zinc 440 ppm, titanium 150 ppm and boron 1 ppm. These impurity contributions * Based on work performed under the auspices of the United States Atomic Energy Commission.t In Itkin's report, the mean level spacing of l~THf should read 3.58 eV and the reduced neutron width at 1 eV of 177Hf and 179Hf should be corrected to 2.11 and 0.843 mV respectively. January 1964)were not entirely insignificant in the data processing. Transmission measurements with a double-pinhole 3 cm-path cell were made, to obtain the total cross section. The observed Debye temperatures, 420 _+ 9 °K for Ni and 240 _+ 6 °K for Hf, possess larger uncertainties than the calorimetric values, 440 °K for Ni (Rayne & Kemp, 1956) and 260 °K for Hf (Wolcott, 1957). Subsequently, the latter values were chosen and low-angle reflections were employed for the coherent intensity measurement.The coherent scattering cross section of hafnium (13.2 barns for nickel) was then found to be 7-59 +0.27 barns at 0.0717 and 0-0460 eV, being significantly different from the previous value of 9.73 barns at about 0.046 eV (Sidhu, Heaton & Zauberis, 1956). The sign of the amplitude, b--0-777_+0.014× 10 -12 cm, was reconfirmed to be positive from the HfC0.95 data. For hafnium metal, the cross section values at 0.0717 eV for the total of coherent scattering with the finite diffraction effect (Bacon, 1962, p. 42). Debye thermal elastic incoherent scattering, and the sum of all other scattering are, respectively, 75.3 _+ 0.2, 5-77, 1.61 and approximately 4.0 barns. The paramagnetic sc...

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“…The authors assumed decomposition to the elements, according to the equation: Equilibrium constants for this reaction, calculated from the tables of thermodynamic functions and the heat of formation given in Chapter A2, are given in Table VIII Mixtures of lithium and carbon were investigated by Fedorov and Mezh-Tsz.en Su [27]. They measured the vapor pressure of mixtures containing 15 atomic°L C in the range 106?…”

Section: Bery Ilium Nitridementioning

confidence: 99%

“…for the dissociation energy of a molecule which they thought to be A1C, The species has not been otherwise observed. This value, reported in NBS Circular 500, is based on a single study of the heat of reaction of lithium carbide with water, by Guntz [27], but is probably not in serious error, because the carbide, an acetylide, is well defined. 13 The low-temperature heat-capacity phase of literature survey and data analysis described in the preliminary report (National 'Bureau of Standards Report No.…”

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confidence: 99%

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Preliminary report on the thermodynamic properties of selected light-element compounds:

1960

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The results of a comprehensive literature survey on the thermodynamic properties of the known nitrides and carbides of Li, Be. Mg, Al, and Ti are presented. Calorimetric heats of formation are examined critically. In the numerous cases where heat-content data are meager or totally lacking, entropies and high-temperature heat capacities were estimated as a basis for provisional tables of high-temperature thermodynamic functions presented for eleven solid (and liquid) nitrides and carbides. Tables are given also for graphite (revised), solid and liquid titanium, and nitrogen gas. These nitrides and carbides decompose by vaporization predominantly to the free elements under the experimental conditions investigated. The reported decomposition data are summarized', and the initial results of examining them for thermodynamic consistency with the thermal data are presented* New experimental data from the Bureau on the preparation and thermodynamic properties of five other light-element compounds are given.Beryllium hydride was prepared by a slight modification of a procedure reported in the literature. New precise heats of formation are given for the perchlorates of ammonium, lithium, and potassium.Preliminary data are given for the vapor pressure and degree of dissociation of the compound AlH^• 2N(CH02* Some results from other institutions are discussed, on (abreactions of ammonia with the hydrides of aluminum and beryllium, and (b) very recently determined entropies and heats of formation of a few light elements and their compounds.A few errors in the two earlier NBS Reports are corrected.iii I

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The atomic heats of titanium, zirconium and hafnium

Cited by 46 publications

References 14 publications

On the High-Frequency Limit of Lattice Vibrations in Zirconium Hydrides and Deuterides

On the High-Frequency Limit of Lattice Vibrations in Zirconium Hydrides and Deuterides

Slow-neutron cross sections of hafnium

Preliminary report on the thermodynamic properties of selected light-element compounds:

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