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Determination of the atomization energies of the gaseous molecules Nb/sub 2/O/sub 4/, Nb/sub 2/O/sub 5/, Nb/sub 4/O/sub 9/, and Nb/sub 4/O/sub 10/

Journal Article · · J. Chem. Phys.; (United States)
OSTI ID:5229969
; ;

The complex gaseous niobium oxide molecules Nb/sub 2/O/sub 4/, Nb/sub 2/O/sub 5/, Nb/sub 4/O/sub 9/, and Nb/sub 4/O/sub 10/ were identified for the first time in a Knudsen cell-mass spectrometric study of the vapors in equilibrium over a condensed phase resulting from extensive vaporization of lithium niobate with lithium depletion. These molecules were characterized thermochemically from the study of several all-gas equilibria. The resulting atomization energies are ..delta..H/sup 0//sub 0,at/(Nb/sub 2/O/sub 4/) = 3322 +- 45 kJ mol/sup -1/; ..delta..H/sup 0//sub 0,at/(Nb/sub 2/O/sub 5/) = 3910 +- 59 kJ mol/sup -1/; ..delta..H/sup 0//sub 0,at/(Nb/sub 4/O/sub 9/) = 7958 +- 82 kJ mol/sup -1/; ..delta..H/sup 0//sub 0,at/(Nb/sub 4/O/sub 10/) = 8595 +- 71 kJ mol/sup -1/. The corresponding standard heats of formation are ..delta..H/sup 0//sub f//sub ,298/(Nb/sub 2/O/sub 4/,g) = -909 +- 45 kJ mol/sup -1/; ..delta..H/sup 0//sub f//sub ,298/(Nb/sub 2/O/sub 5/,g) = -1252 +- 59 kJ mol/sup -1/; ..delta..H/sup 0//sub f//sub ,298/(Nb/sub 4/O/sub 9/,g) = -2889 +- 82 kJ mol/sup -1/; ..delta..H/sup 0//sub f//sub ,298/(Nb/sub 4/O/sub 10/,g) = -3281 +- 71 kJ mol/sup -1/.

Research Organization:
Dipartimento di Chimica, Universita di Roma-La Sapienza, 00185 Roma, Italy
OSTI ID:
5229969
Journal Information:
J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 85:10; ISSN JCPSA
Country of Publication:
United States
Language:
English

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Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
ALKALI METAL COMPOUNDS
ATOMIZATION
CHALCOGENIDES
ENTHALPY
EQUILIBRIUM
EVAPORATION
FLUIDS
FORMATION HEAT
GASES
LITHIUM COMPOUNDS
MASS SPECTROSCOPY
NIOBATES
NIOBIUM COMPOUNDS
NIOBIUM OXIDES
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
REACTION HEAT
REFRACTORY METAL COMPOUNDS
SPECTROSCOPY
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS