Bonding and site preferences in the new quasi-binary Zr{sub 2.7}Hf{sub 11.3}P{sub 9}

Journal Article · Sun Mar 01 04:00:00 EST 1998 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1006/jssc.1997.7684· OSTI ID:642169

Kleinke, H; Franzen, H F ^[1]

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1. Ames Lab., IA (United States)

The new quasi-binary Zr{sub 2.7}Hf{sub 11.3}P{sub 9} was synthesized by arc-melting of Zr, Hf, Co, and HfP in a ratio corresponding to the initial composition Zr{sub 2.25}Hf{sub 6.75}Co{sub 2}P{sub 4}. Zr{sub 2.7}Hf{sub 11.3}P{sub 9} crystallizes in the Zr{sub 14}P{sub 9} structure type, which is unknown in the binary Hf/P system. the ideal orthorhomibic lattice dimensions (space group Pnnm (No. 58), Z = 4) were refined to a = 16.640(7) {angstrom}, b = 27.40(2) {angstrom}, c = 3.619(1) {angstrom}, V = 1650(2) {angstrom}{sup 3}. The structure consists of three-dimensional condensed one-, two-, and three-capped trigonal (Zr, Hf){sub 6}P prisms, occurring with numerous short M-M bonds (M = Zr, Hf). Each of the 15 metal sites is statistically occupied by a mixture of Zr and Hf, which varies significantly from site to site. The Hf/Zr ratio in a given site depends on the M-M and M-P interactions. The systematic increase of this ratio with increasing total bond order, as evaluated via Mulliken overlap populations and Pauling bond orders, can be understood based on the trend that Hf forms stronger M-M and M-P bonds than Zr. As expected for a metal-rich phosphide, band structure calculations for the hypothetical Hf{sub 14}P{sub 9} carried out with the extended Hueckel approximation result in a significant density of states at the Fermi level.

• Sponsoring Organization: USDOE, Washington, DC (United States); Deutsche Forschungsgemeinschaft, Bonn (Germany)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 642169
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 2 Vol. 136; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
EXPERIMENTAL DATA
HAFNIUM PHOSPHIDES
LATTICE PARAMETERS
ORTHORHOMBIC LATTICES
STOICHIOMETRY
ZIRCONIUM PHOSPHIDES