Vapour pressures of solid and liquid NbCl<sub>5</sub> and TaCl<sub>5</sub>

Sadoway, Donald R.; Flengas, S. N.

doi:10.1139/v76-240

Cited by 18 publications

(15 citation statements)

References 11 publications

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“…Since [I21 was derived by subtracting [5] from [6], given in Table 3, the temperature dependence on the equilibrium constant given by [13] may be calculated by combining [7] and [8] as: [14] In K c , = 1.799 -(951/T) st. dev. = 0.1097 A plot ofK,, vs. T (in "C) is shown in Fig.…”

Section: Discussionmentioning

confidence: 99%

“…The quartz spiral type gauge was used recently in this laboratory (8) and was found to be superior to both the spoon type Bourdon gauges (I, 2) and the molten tin isoteniscopes (3,4) used previously, because of its ability to sustain large and sudden pressure changes of a n order of 1 atni without shattering. This eliminated the need for close supervision of the apparatus.…”

Section: Introductionmentioning

confidence: 97%

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Equilibrium decomposition pressures of the compounds K₂ZrCl₆ and K₂HfCl₆

Kipouros¹,

Flengas²

1978

Can. J. Chem.

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The chemical equilibria representing the reactions[Formula: see text]and[Formula: see text]were investigated by direct vapour pressure measurements. The thermodynamic data for these reactions, such as free energies and enthalpies of reaction, have been calculated. With reference to the separation of Hf from Zr by a recently developed process based on the selective reactivity of ZrCI4 and HfCl4 vapours with alkali chlorides, it is shown that KCl is a better separating agent than LiCl.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Equilibrium decomposition pressures of the compounds K₂ZrCl₆ and K₂HfCl₆

Kipouros¹,

Flengas²

1978

Can. J. Chem.

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“…The same trend has been confirmed when using the 4-windowless EDS detectors separately, which rules out the influence of geometrical effects on these chemical maps. 39 Since the vapor pressure of TaCl 5 is higher than that of NbCl 5 , 40 it is suggested that the lower side of the imaged nanotube is indeed the root, while its upper side presents the top of the grown nanotube. The details of the growth mechanism of LaS-TaS 2 nanotubes have not been resolved as yet.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Along the long axis, the Nb/Ta ratio shows large variations, decreasing from 3.40 (position 1 top-center) to 0.73 (position 5 bottom-center). Again, the lower vapor pressure of NbCl 5 , compared to that of TaCl 5 , 40 suggests that the root of the tube is in the lower part of the image (5), whereas point 1 represents the termination of the nanotube growth. The La/ (Nb+Ta) ratio decreases from 0.92 in the bottom (5) to 0.70 in the top reflecting the enrichment of Nb in the NT lattice along the growth axis of the nanotube.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Nanotubes from the Misfit Compound Alloy LaS-Nb_xTa_(1–x)S₂

Stolovas¹,

Serra²,

Popovitz‐Biro³

et al. 2018

Chem. Mater.

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Misfit layered compounds (MLC) with the composition (LaS) 1.15 TaS 2 (for simplicity denoted as LaS-TaS 2) and LaS-NbS 2 were prepared and studied in the past. Nanotubes of LaS-TaS 2 could be easily synthesized, while tubular structure of the LaS-NbS 2 were found to be rather rare in the product. In order to understand this riddle, quaternary alloys of LaS-Nb x Ta (1-x) S 2 with ascending Nb concentration were prepared herein in the form of nanotubes (and platelets). Not surprisingly, the concentration of these quaternary nanotubes shrinked (and the relative density of platelets increased) with increasing Nb content in the precursor. The structure and chemical composition of such nanotubes was elucidated by electron microscopy. Conceivably, the TaS 2 in the MLC compounds LnS-TaS 2 (Ln=lanthanide atom) crystallizes in the 2H polytype. High resolution transmission electron microscopy showed however that, invariably MLC nanotubes prepared from 80 at% Nb content in the precursor belonged to the 1T polytype. Raman spectroscopy of individual tubes revealed that up to 60 at% Nb, they obey the standard model of MLC, while higher Nb lead to large deviations which are discussed in brief. The analysis indicated also that such nanotubes do not exhibit the pattern assigned to charge density wave transition so typical for binary 1T-TaS 2. The prospect for revealing interesting quasi-1D behavior of such quaternary nanotubes is also briefly discussed.

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“…The MCI, was heated to the temperature at which its pressure was approximately 1.5 atnl, i.e. 266°C for NbCI, and 257-C for TaCI, (7). Except in the case of the NaCl the other alkali chlorides were heated to approxin~ately 10'C above the melting point of the corresponding AMCI6 con~pound.…”

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confidence: 99%