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 · Sat Nov 15 00:00:00 EST 1986 · J. Chem. Phys.; (United States)

OSTI ID:5229969

Balducci, G; Gigli, G; Guido, M

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), Vol. 85:10
• Country of Publication: United States
• Language: English

Related Subjects

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