The preparation and characterization of high surface area transition metal nitrides

Miscellaneous · Fri Jan 01 00:00:00 EST 1988

OSTI ID:7022477

Jaggers, C H

This study is concerned with the synthesis of high-surface-area molybdenum and vanadium nitrides by the reaction of oxide and ammonium oxide precursors with ammonia. The reactions have been followed using thermogravimetric analysis (TGA) and high temperature X-Ray diffraction (XRD) to determine reaction intermediates, while the development of surface area was investigated by interrupting the TGA experiments and measuring the surface area using the BET method. Molybdenum trioxide and ammonium paramolybdate react to form high surface area Mo{sub 2}N and a mixture of MoN and Mo{sub 2}N, respectively. Diammonium molybdate reacts with ammonia to form low surface area MoN. Each compound reacts through a different pathway to form a common MoO{sub x}N{sub 1-x} oxynitride intermediate, which subsequently reacts to form the nitride product. The nitride phase formed is determined by the temperature at which the oxynitride reacts, while the structure of the oxynitride precursor influences the ultimate surface area. The reactions of V{sub 2}O{sub 5}, VO{sub 2}, V{sub 2}O{sub 3}, and NH{sub 4}VO{sub 3} with ammonia all produce low surface area vanadium oxynitrides at 750C. Each reaction proceeds through a series of lower vanadium oxide intermediates. In all reaction, V{sub 2}O{sub 3} is the precursor to the oxynitride. The use of hydrogen bronzes of molybdenum trioxide and vanadium pentoxide as starting materials lowers the reaction temperatures, but does not alter the nitridification reaction networks. In the case of molybdenum trioxide, however, insertion of hydrogen eliminates the formation of molybdenum dioxide which is a by-product of the reaction of MoO{sub 3} with ammonia.

• Research Organization: California Univ., Berkeley, CA (USA)
• OSTI ID: 7022477
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
MOLYBDENUM NITRIDES
CHEMICAL PREPARATION
VANADIUM NITRIDES
AMMONIA
AMMONIUM COMPOUNDS
CHEMICAL PROPERTIES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
HYDROGEN
MOLYBDENUM OXIDES
OXIDES
REACTION INTERMEDIATES
SURFACE AREA
SURFACE PROPERTIES
THERMAL GRAVIMETRIC ANALYSIS
VANADIUM OXIDES
X-RAY DIFFRACTION
CHALCOGENIDES
CHEMICAL ANALYSIS
COHERENT SCATTERING
DIFFRACTION
ELEMENTS
GRAVIMETRIC ANALYSIS
HYDRIDES
HYDROGEN COMPOUNDS
KINETICS
MOLYBDENUM COMPOUNDS
NITRIDES
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NONMETALS
OXYGEN COMPOUNDS
PNICTIDES
QUANTITATIVE CHEMICAL ANALYSIS
REACTION KINETICS
REFRACTORY METAL COMPOUNDS
SCATTERING
SYNTHESIS
THERMAL ANALYSIS
TRANSITION ELEMENT COMPOUNDS
VANADIUM COMPOUNDS
400201* - Chemical & Physicochemical Properties