Pressure-induced amorphization of cubic ZrW{sub 2}O{sub 8} studied in situ and ex situ by synchrotron x-ray diffraction and absorption
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400 (United States)
The behavior of cubic ZrW{sub 2}O{sub 8} on compression in a DAC to 7.6 GPa was examined in situ by a combination of synchrotron x-ray diffraction and x-ray absorption spectroscopy (XAS). These data were compared with x-ray absorption measurements on an amorphous sample of ZrW{sub 2}O{sub 8} recovered from 7.5 GPa in a multianvil apparatus. The in situ diffraction data show the complete formation of orthorhombic ZrW{sub 2}O{sub 8} at low pressure (<0.5 GPa), and amorphization onset at >2.4 GPa with completion at <7.6 GPa. The corresponding in situ XAS data suggest a continuous evolution of the local tungsten coordination environment on compression after forming the orthorhombic phase, with the average W-O bond length increasing, indicating an increase in the average coordination number, and the W L{sub I} pre-edge peak decreasing in magnitude, indicating a movement toward tungsten coordination that is closer to centrosymmetric These observations are inconsistent with a model for the amorphization that simply involves a loss of orientational/positional order among existing coordination polyhedra. The XANES data for the amorphous sample recovered from the multianvil apparatus are unlike any of the XANES seen in the in situ measurements, suggesting that the local structure in the glassy material relaxes on decompression. The XANES for the recovered sample are very similar to those for ammonium paratungstate, a material that contains tungsten in a variety of heavily distorted octahedral environments.
- OSTI ID:
- 20719122
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Journal Name: Physical Review. B, Condensed Matter and Materials Physics Journal Issue: 2 Vol. 72; ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
Similar Records
Structural Description of Pressure-Induced Amorphization in ZrW{sub 2}O{sub 8}
A new polymorph of ZrW{sub 2}O{sub 8} prepared using nonhydrolytic sol-gel chemistry