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Title: Thermodynamics of the volatilization of Tl[sub 2]O from Tl[sub 2]O, Tl[sub 4]O[sub 3], and Tl[sub 2]O[sub 3]

Abstract

Volatile thallous oxide, Tl[sub 2]O, is used in the fabrication of thallium-containing high-temperature superconducting powders and films. The partial pressure of thallous oxide was measured as a function of temperature and oxygen partial pressure by the transportation method over liquid and solid Tl[sub 2]O, liquid and solid Tl[sub 4]O[sub 3], and solid Tl[sub 2]O[sub 3]. At low oxygen partial pressure, condensed Tl[sub 2]O is stable with respect to Tl[sub 4]O[sub 3] and Tl[sub 2]O[sub 3]. It melts at 852 [+-] 10 K and is very volatile, with a vapor pressure of about 1.0 [times] 10[sup [minus]2] atm at 900 K. At high oxygen partial pressure, Tl[sub 2]O[sub 3] is stable with respect to Tl[sub 2]O and Tl[sub 4]O[sub 3]. It does not melt congruently below 1,067 K. It volatilizes congruently through the reaction Tl[sub 2]O[sub 3](c) = Tl[sub 2]O(g) + O[sub 2](g), and the equilibrium vapor pressure of Tl[sub 2]O in oxygen at atmospheric pressure reaches 1.0 [times] 10[sup [minus]2] atm at about 1,050 K. Tl[sub 4]O[sub 3] exists as a thermodynamically stable phase at intermediate oxygen partial pressure. It melts at 990 [+-] 2 K, and it volatilizes congruently through the reaction Tl[sub 4]O[sub 3](c) = 2 Tl[sub 2]O(g)more » + 1/2O[sub 2](g). Thermodynamic properties for Tl[sub 4]O[sub 3](c) are estimated to be [Delta][sub f]H[degrees][sub 298] = [minus]520.7 kJ/mol and S[degrees][sub 298] = 259.0 J/(mol K). The experimental results of this study were combined with data in previous studies to estimate the high temperature thermodynamic properties of the thallium oxide phases. These properties were used to generate a phase diagram for the Tl-O system and to determine the equilibrium vapor pressure of thallous oxide over the condensed phases as a function of temperature and oxygen partial pressure. 30 refs., 10 figs., 3 tabs.« less

Authors:
 [1]
  1. Du Pont Central Research Development, Wilmington, DE (United States)
Publication Date:
OSTI Identifier:
5713368
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry; (United States)
Additional Journal Information:
Journal Volume: 97:16; Journal ID: ISSN 0022-3654
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; THALLIUM OXIDES; EVAPORATION; THERMODYNAMIC PROPERTIES; EQUILIBRIUM; HIGH-TC SUPERCONDUCTORS; PARTIAL PRESSURE; PHASE DIAGRAMS; RAW MATERIALS; TEMPERATURE DEPENDENCE; THEORETICAL DATA; CHALCOGENIDES; DATA; DIAGRAMS; INFORMATION; MATERIALS; NUMERICAL DATA; OXIDES; OXYGEN COMPOUNDS; PHASE TRANSFORMATIONS; PHYSICAL PROPERTIES; SUPERCONDUCTORS; THALLIUM COMPOUNDS; 400201* - Chemical & Physicochemical Properties; 360600 - Other Materials; 360607 - Other Materials- Superconducting Properties- (1992-); 661300 - Other Aspects of Physical Science- (1992-)

Citation Formats

Holstein, W L. Thermodynamics of the volatilization of Tl[sub 2]O from Tl[sub 2]O, Tl[sub 4]O[sub 3], and Tl[sub 2]O[sub 3]. United States: N. p., 1993. Web. doi:10.1021/j100118a046.
Holstein, W L. Thermodynamics of the volatilization of Tl[sub 2]O from Tl[sub 2]O, Tl[sub 4]O[sub 3], and Tl[sub 2]O[sub 3]. United States. https://doi.org/10.1021/j100118a046
Holstein, W L. 1993. "Thermodynamics of the volatilization of Tl[sub 2]O from Tl[sub 2]O, Tl[sub 4]O[sub 3], and Tl[sub 2]O[sub 3]". United States. https://doi.org/10.1021/j100118a046.
@article{osti_5713368,
title = {Thermodynamics of the volatilization of Tl[sub 2]O from Tl[sub 2]O, Tl[sub 4]O[sub 3], and Tl[sub 2]O[sub 3]},
author = {Holstein, W L},
abstractNote = {Volatile thallous oxide, Tl[sub 2]O, is used in the fabrication of thallium-containing high-temperature superconducting powders and films. The partial pressure of thallous oxide was measured as a function of temperature and oxygen partial pressure by the transportation method over liquid and solid Tl[sub 2]O, liquid and solid Tl[sub 4]O[sub 3], and solid Tl[sub 2]O[sub 3]. At low oxygen partial pressure, condensed Tl[sub 2]O is stable with respect to Tl[sub 4]O[sub 3] and Tl[sub 2]O[sub 3]. It melts at 852 [+-] 10 K and is very volatile, with a vapor pressure of about 1.0 [times] 10[sup [minus]2] atm at 900 K. At high oxygen partial pressure, Tl[sub 2]O[sub 3] is stable with respect to Tl[sub 2]O and Tl[sub 4]O[sub 3]. It does not melt congruently below 1,067 K. It volatilizes congruently through the reaction Tl[sub 2]O[sub 3](c) = Tl[sub 2]O(g) + O[sub 2](g), and the equilibrium vapor pressure of Tl[sub 2]O in oxygen at atmospheric pressure reaches 1.0 [times] 10[sup [minus]2] atm at about 1,050 K. Tl[sub 4]O[sub 3] exists as a thermodynamically stable phase at intermediate oxygen partial pressure. It melts at 990 [+-] 2 K, and it volatilizes congruently through the reaction Tl[sub 4]O[sub 3](c) = 2 Tl[sub 2]O(g) + 1/2O[sub 2](g). Thermodynamic properties for Tl[sub 4]O[sub 3](c) are estimated to be [Delta][sub f]H[degrees][sub 298] = [minus]520.7 kJ/mol and S[degrees][sub 298] = 259.0 J/(mol K). The experimental results of this study were combined with data in previous studies to estimate the high temperature thermodynamic properties of the thallium oxide phases. These properties were used to generate a phase diagram for the Tl-O system and to determine the equilibrium vapor pressure of thallous oxide over the condensed phases as a function of temperature and oxygen partial pressure. 30 refs., 10 figs., 3 tabs.},
doi = {10.1021/j100118a046},
url = {https://www.osti.gov/biblio/5713368}, journal = {Journal of Physical Chemistry; (United States)},
issn = {0022-3654},
number = ,
volume = 97:16,
place = {United States},
year = {Thu Apr 22 00:00:00 EDT 1993},
month = {Thu Apr 22 00:00:00 EDT 1993}
}