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Title: Enthalpy of formation of gallium nitride

Abstract

A major discrepancy in the literature concerning the enthalpy of formation of GaN has been resolved using oxidative oxide melt solution calorimetry. Four samples of differing nitrogen contents were measured by dropping them into molten 3Na{sub 2}O{center_dot}4MoO{sub 3} in a calorimeter at 975 K with oxygen gas bubbling through the solvent. The samples were characterized by X-ray diffraction, chemical analysis, transmission electron microscopy, particle size analysis, and BET measurements. The enthalpy of drop solution (kJ/g) varied approximately linearly with nitrogen content. Extrapolated to stoichiometric GaN, the data yield a value of {minus}156.8 {+-} 16.0 kJ/mol for the standard enthalpy of formation from the elements at 298 K. The relatively large error reflects the deviation of individual points from the straight line rather than uncertainties in each set of data for a given sample. This new directly measured enthalpy of formation is in excellent agreement with that obtained from the temperature dependence of the equilibrium pressure of nitrogen over GaN, {minus}157.7 kJ/mol, measured by Madar et al. and Karpinski and Porowski. This value of {minus}156.8 kJ/mol should replace the commonly tabulated value of {minus}110 kJ/mol determined by Hahn and Juza using combustion calorimetry on an uncharacterized sample over 50 years ago.

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Univ. of California, Davis, CA (US)
Sponsoring Org.:
USDOE
OSTI Identifier:
20050841
DOE Contract Number:  
FG03-97ER45654
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical
Additional Journal Information:
Journal Volume: 104; Journal Issue: 17; Other Information: PBD: 4 May 2000; Journal ID: ISSN 1089-5647
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; GALLIUM NITRIDES; FORMATION HEAT; SYNTHESIS; CALORIMETRY; MOLTEN SALTS; MOLYBDATES; SODIUM COMPOUNDS; SOLVENTS

Citation Formats

Ranade, M.R., Tessier, F., Navrotsky, A., Leppert, V.J., Risbud, S.H., DiSalvo, F.J., and Balkas, C.M. Enthalpy of formation of gallium nitride. United States: N. p., 2000. Web. doi:10.1021/jp993752s.
Ranade, M.R., Tessier, F., Navrotsky, A., Leppert, V.J., Risbud, S.H., DiSalvo, F.J., & Balkas, C.M. Enthalpy of formation of gallium nitride. United States. doi:10.1021/jp993752s.
Ranade, M.R., Tessier, F., Navrotsky, A., Leppert, V.J., Risbud, S.H., DiSalvo, F.J., and Balkas, C.M. Thu . "Enthalpy of formation of gallium nitride". United States. doi:10.1021/jp993752s.
@article{osti_20050841,
title = {Enthalpy of formation of gallium nitride},
author = {Ranade, M.R. and Tessier, F. and Navrotsky, A. and Leppert, V.J. and Risbud, S.H. and DiSalvo, F.J. and Balkas, C.M.},
abstractNote = {A major discrepancy in the literature concerning the enthalpy of formation of GaN has been resolved using oxidative oxide melt solution calorimetry. Four samples of differing nitrogen contents were measured by dropping them into molten 3Na{sub 2}O{center_dot}4MoO{sub 3} in a calorimeter at 975 K with oxygen gas bubbling through the solvent. The samples were characterized by X-ray diffraction, chemical analysis, transmission electron microscopy, particle size analysis, and BET measurements. The enthalpy of drop solution (kJ/g) varied approximately linearly with nitrogen content. Extrapolated to stoichiometric GaN, the data yield a value of {minus}156.8 {+-} 16.0 kJ/mol for the standard enthalpy of formation from the elements at 298 K. The relatively large error reflects the deviation of individual points from the straight line rather than uncertainties in each set of data for a given sample. This new directly measured enthalpy of formation is in excellent agreement with that obtained from the temperature dependence of the equilibrium pressure of nitrogen over GaN, {minus}157.7 kJ/mol, measured by Madar et al. and Karpinski and Porowski. This value of {minus}156.8 kJ/mol should replace the commonly tabulated value of {minus}110 kJ/mol determined by Hahn and Juza using combustion calorimetry on an uncharacterized sample over 50 years ago.},
doi = {10.1021/jp993752s},
journal = {Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical},
issn = {1089-5647},
number = 17,
volume = 104,
place = {United States},
year = {2000},
month = {5}
}