The vapour pressure and evaporation thermodynamics of sodium iodide

Mucklejohn, Stuart A.; O'Brien, N.W.

doi:10.1016/0021-9614(84)90061-2

Cited by 12 publications

(5 citation statements)

References 8 publications

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“…As far as the vaporization thermodynamics of ScI3 and NaI are concerned, perhaps the major contributions of this work are the independent torsion-effusion vapor molecular weights, showing that, in both instances, the dimers are relatively minor species in the saturated vapor, even up to (16), which were used in the analysis of some of the earlier work (14,15,17), suggest a much higher fraction of dimer, but these results ( 16) must be in error.…”

Section: Discussionmentioning

confidence: 74%

“…Our measurements indicate a total pressure of 3.2 x 10 -4 arm at the NaI melting point, 933 K. Our TGA vapor pressure data on molten NaI are about 25% lower than previous results by Mucklejohn and O'Brien ( 14) but 40% higher than those of Topor (15), both measured by the quasistatic method. These workers (14,15) used NaI vapor composition data from Datz and Smith (16) to derive monomer and dimer partial pressures, corresponding to dimer levels of 50-60 m/o. However, such a high dimer level is quite inconsistent with our torsion vapor molecular weights and derived thermodynamic properties, which predict a dimer abundance of about 10-15 m/o at 1200-1490 K. Interpretation of the NaI transpiration measurements by Work (17) is dependent 0n vapor Composition; it would seem that they could be best interpreted in terms of a largely monomeric vapor.…”

Section: Investigatormentioning

confidence: 99%

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Thermodynamics of Gaseous Species in the Sodium‐Scandium‐Iodine System

Hildenbrand

Lau

Russell

et al. 1990

J. Electrochem. Soc.

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The vaporization behavior of NaI(s), ScI3(s), and mixtures of these two phases containing 50, 92, 95, and 98 mole percent (m/o) NaI has been studied by effusion-beam mass spectrometry and by torsion-mass-effusion techniques in the approximate region 700-900 K. Vapor molecular weights show that NaI and SCI3 monomers make up 84 and 94 m/o, respectively, of the saturated vapors over the pure phases with the balance primarily dimer. NaScI4 is the maj or gaseous species over the mixtures, with a small amount of Na2ScI5 also present. Total vapor pressures of the pure phases and the mixtures were determined by the torsion method, and the enthalpies of sublimation of the monomer and dimer species over NaI and ScI3 were determined. The total vapor pressures of molten NaI and the NaI-ScI3 mixtures were also measured in the 10 2-10 -1 atm range by the TGA boiling point method, and vapor mass spectra were used to estimate the activities of'NaI and ScI3 in the liquid mixtures. Additionally, gaseous equilibria involving NaScI4 as well as the lower valent species ScI and ScI2 were studied by mass spectrometry. Vapor thermodynamic properties were derived and are compared with results in the literature.

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Section: Discussionmentioning

confidence: 74%

Section: Investigatormentioning

confidence: 99%

Thermodynamics of Gaseous Species in the Sodium‐Scandium‐Iodine System

Hildenbrand

Lau

Russell

et al. 1990

J. Electrochem. Soc.

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“…The limitations associated with the determination of partial pressure from vapor-pressure measurements and the equilibrium constant for the monomer + dimer equilibrium have been described in detail elsewhere. 19 Zaugg and Gregory11 only report the partial pressure of Fel2 above solid iron(II) iodide; they do not list the partial pressure of Fe2I4. We have determined the partial pressure of Fe2I4 from their work by subtracting p(FeI2+I2) from the total pressure measurements of Schafer and Hones.28 The partial pressures of Fel2 above solid iron(II) iodide from this work and from ref 11 are compared in Figure 5.…”

Section: Discussionmentioning

confidence: 99%

“…The details of our procedure and apparatus have been reported previously. 19 A series of five experiments were carried out requiring 15 g of sample for each. All handling operations were carried out in an argon-filled drybox.…”

Section: Methodsmentioning

confidence: 99%

High-purity iron(II) iodide: preparation, vapor pressure, and vapor composition, 792 to 1138 K

Mucklejohn¹,

O'Brien²,

Brumleve³

1985

J. Phys. Chem.

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“…Vapor pressure measurements were made using the Rodebush and Dixon method (19). Details of our apparatus and procedure have been reported previously (20). The sample cells were fabricated from Thermal Syndicate grade four electrically fused silica.…”

Section: Methodsmentioning

confidence: 99%

The Chemical Composition of Plasmas Generated in High Pressure Discharge Lamps Containing Tin and Sodium Halides

Mucklejohn¹,

Jones²,

Mottram³

et al. 1987

J. Electrochem. Soc.

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In order to model high pressure discharge lamps which contain metal halides, the chemical composition in the plasma region is required. We have developed a procedure for calculating the composition of a plasma in local thermodynamic equilibrium, between 1500 and 6000 K, including the effect of radial diffusion. Mixtures of tin halides and sodium halides, when added to high pressure mercury discharges, produce highly efficient white light sources. We have determined the saturated vapor phase composition of some tin halide/sodium halide mixtures using the results from Knudsen effusion/ mass spectrometric, vapor pressure, and transpiration studies. We report herein a detailed study of the SnC12 + NaC1 (50:50) system and a preliminary investigation of the SnC12 + NaI (50:50) system together with the plasma compositions for the corresponding lamps. These results show that radial diffusion has a highly significant effect on the plasma composition.Our understanding of high pressure sodium lamps has been deepened through the development of a computer model (1). The model is based on solving the energy balance equation to give the radial temperature distribution of an arc. We assume that the electrical energy dissipated in an elemental volume equals the sum of the net heat and radiation losses. The variation of the chemical composition of the plasma with temperature stands at the heart of the model, and is used in the calculations of thermal and electrical conductivities and of radiation losses.A knowledge of the temperature profile enables us to predict the electrical and spectral characteristics of the arc. We have used our model to investigate the variation of efficacy for a high pressure sodium lamp with arc tube bore and current (2), and with arc tube temperature and electrical power dissipation (3). The model has thus contributed directly to the development and improvement of high pressure sodium lamps.Metal halide lamps are able to combine good color appearance and good color rendition with compact size, giving rise to highly efficient white light sources. A large variety of metal halide lamps are available on the market, these are generally confined to powers above 150W. Such lamps are employed in many applications: industrial and commercial interior lighting; exterior floodlighting; theater and stage lighting; set lighting; image projection systems; photoprinting; water sterilization; plant growth; street lighting. The present trend is towards lower power lamps, say below 150W, for use in display lighting. The development of successful low wattage metal halide lamps has proved to be a considerable challenge to the lamp manufacturing industry. To date, only a few low power metal halide lamps are available.The addition of tin halide/sodium halide mixtures to high pressure mercury discharges has been shown to produce lamps which combine high efficacy with good color rendition (4). The inclusion of metal halide systems in high pressure lamps gives rise to both atomic and molecular radiation, the latter being broad-ba...

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The vapour pressure and evaporation thermodynamics of sodium iodide

Cited by 12 publications

References 8 publications

Thermodynamics of Gaseous Species in the Sodium‐Scandium‐Iodine System

Thermodynamics of Gaseous Species in the Sodium‐Scandium‐Iodine System

High-purity iron(II) iodide: preparation, vapor pressure, and vapor composition, 792 to 1138 K

The Chemical Composition of Plasmas Generated in High Pressure Discharge Lamps Containing Tin and Sodium Halides

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