Phase diagram of the system Bi/sub 2/O/sub 3/-MoO/sub 3/

Journal Article · Sun Jul 01 04:00:00 EDT 1979 · J. Catal.; (United States)

OSTI ID:5854470

Egashira, M ^[1]; Matsuo, K; Kagawa, S; Seiyama, T

---

1. Nagasaki Univ., Japan

The phase diagram of the Bi/sub 2/O/sub 3/-MoO/sub 3/ system was studied by X-ray diffraction and differential thermal analysis, in particular in the range Bi/Mo = 2/1 approx. 2/3 of interest for catalysis. X-ray diffraction identified the following eight compounds: 7Bi/sub 2/O/sub 3/ . MoO/sub 3/, 3Bi/sub 2/O/sub 3/ . MoO/sub 3/, low and high temperature forms of 3Bi/sub 2/O/sub 3/ . 2MoO/sub 3/, koechlinite, and high temperature forms of Bi/sub 2/O/sub 3/ . MoO/sub 3/, Bi/sub 2/O/sub 3/ . 2MoO/sub 3/, and Bi/sub 2/O/sub 3/ . 3MoO/sub 3/. The low temperature form of 3Bi/sub 2/O/sub 3/ . 2MoO/sub 3/ is a new modification of the Bi/Mo = 3 compound, while 7Bi/sub 2/O/sub 3/ . MoO/sub 3/ corresponds to that reported hitherto as approx. 10Bi/sub 2/O/sub 3/ . MoO/sub 3/, and others are identical to those found before. Bi/sub 2/O/sub 3/ . 3MoO/sub 3/ forms eutectics with MoO/sub 3/ at 615/sup 0/C and with Bi/sub 2/O/sub 3/ . 2MoO/sub 3/ at 640/sup 0/C. Bi/sub 2/O/sub 3/ . 2MoO/sub 3/ is generated by the peritectic reaction of the liquid phase and the high temperature phase of Bi/sub 2/O/sub 3/ . MoO/sub 3/ at 665/sup 0/C. Bi/sub 2/O/sub 3/ . 2MoO/sub 3/ is stable in the range from 665 to 540/sup 0/C, below which it disproportionates into Bi/sub 2/O/sub 3/ . 3 MoO/sub 3/ and the koechlinite form of Bi/sub 2/O/sub 3/ . MoO/sub 3/. The high temperature form of Bi/sub 2/O/sub 3/ . MoO/sub 3/ is also formed by the peritectic reaction of the liquid and the high temperature phase of 3Bi/sub 2/O/sub 3/ . 2MoO/sub 3/. The transition temperatures between two modifications in Bi/sub 2/O/sub 3/ . MoO/sub 3/ and in 3Bi/sub 2/O/sub 3/ . 2MoO/sub 3/ are supposed to be 600 and 750/sup 0/C, respectively. 3Bi/sub 2/O/sub 3/ . MoO/sub 3/ forms a eutectic with 3Bi/sub 2/O/sub 3/ . 2MoO/sub 3/ at 950/sup 0/C, and a solid solution with Bi/sub 2/O/sub 3/. 6 figures, 3 tables.

• OSTI ID: 5854470
• Journal Information: J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 58:3; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
BISMUTH COMPOUNDS
BISMUTH OXIDES
CATALYSIS
CATALYTIC EFFECTS
CHALCOGENIDES
COHERENT SCATTERING
DIAGRAMS
DIFFERENTIAL THERMAL ANALYSIS
DIFFRACTION
DISPERSIONS
EUTECTICS
MIXTURES
MOLYBDENUM COMPOUNDS
MOLYBDENUM OXIDES
OXIDES
OXYGEN COMPOUNDS
PHASE DIAGRAMS
SCATTERING
SOLID SOLUTIONS
SOLUTIONS
STRUCTURAL CHEMICAL ANALYSIS
THERMAL ANALYSIS
TRANSITION ELEMENT COMPOUNDS
X-RAY DIFFRACTION