Studies of high temperature ternary phases in mixed-metal-rich early transition metal sulfide and phosphide systems

Thesis/Dissertation · Tue Jan 04 04:00:00 EST 1994

DOI:https://doi.org/10.2172/10119308· OSTI ID:10119308

Marking, Gregory Allen ^[1]

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1. Iowa State Univ., Ames, IA (United States)

Investigations of ternary mixed early transition metal-rich sulfide and phosphide systems resulted in the discovery of new structures and new phases. A new series of Zr and Hf - group V transition metal - sulfur K-phases was synthesized and crystallographically characterized. When the group V transition metal was Nb or Ta, the unit cell volume was larger than any previously reported K-phase. The presence of adventitious oxygen was determined in two K-phases through a combination of neutron scattering and X-ray diffraction experiments. A compound Hf₁₀Ta₃S₃ was found to crystallize in a new-structure type similar to the known gamma brasses. This structure is unique in that it is the only reported "stuffed" gamma-brass type structure. The metal components, Hf and Ta, are larger in size and more electropositive than the metals found in normal gamma brasses (e.g. Cu and Zn) and because of the larger metallic radii, sulfur can be incorporated into the structure where it plays an integral role in stabilizing this phase relative to others. X-ray single-crystal, X-ray powder and neutron powder refinements were performed on this structure. A new structure was found in the ternary Nb-Zr-P system which has characteristics in common with many known early transition metal-rich sulfides, selenides, and phosphides. This structure has the simplest known interconnection of the basic building blocks known for this structural class. Anomalous scattering was a powerful tool for differentiating between Zr and Nb when using Mo Kα X-radiation. The compounds ZrNbP and HfNbP formed in the space group Prima with the simple Co₂Si structure which is among the most common structures found for crystalline solid materials. Solid solution compounds in the Ta-Nb-P, Ta-Zr-P, Nb-Zr-P, Hf-Nb-P, and Hf-Zr-S systems were crystallographically characterized. The structural information corroborated ideas about bonding in metal-rich compounds.

• Research Organization: Ames Lab., IA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 10119308
• Report Number(s): IS-T--1646; ON: DE94006034
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202
CRYSTAL STRUCTURE
CRYSTALLOGRAPHY
HAFNIUM COMPOUNDS
NIOBIUM COMPOUNDS
PHASE STUDIES
PHOSPHIDES
STRUCTURAL CHEMICAL ANALYSIS
STRUCTURE AND PHASE STUDIES
SULFIDES
TANTALUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
ZIRCONIUM COMPOUNDS