High-pressure polymorphism ofPbF2to 75 GPa

High-pressure polymorphism of cyclopentanol (C5H10O): the structure of cyclopentanol phase-V at 1.5 GPa.

The fully ordered high-pressure crystal structure of cyclopentanol (C5H10O) has been solved using single-crystal X-ray diffraction techniques on station 9.8 at the SRS Daresbury Laboratory. At pressures above 1.5 GPa, cyclopentanol crystallizes in the monoclinic P2(1)/c space group with a=17.882 (3), b=5.4573 (3), c=9.6817 (14) A, beta=104.699 (8) degrees and Z'=2. The crystal structure is char...

High pressure structural studies on Nb5Si3 up to 26.2 GPa

High Pressure Polymorphism in Silica

Fundamental crystal chemistry and first-principles total-energy calculations are used to examine stable and metastable high-pressure silica structures. We find that a large class of energetically competitive phases can be generated from hcp arrays of oxygen with silicon occupying one-half of the octahedral sites. Calculations for specific structures provide an explanation for a number of recent...

High pressure polymorphism of β-TaON.

The high pressure behavior of TaON was studied using a combination of Raman scattering, synchrotron X-ray diffraction, and X-ray absorption spectroscopy in diamond anvil cells to 70 GPa at ambient temperature. A Birch-Murnaghan equation of state fit for baddeleyite structured β-TaON indicates a high bulk modulus value Ko = 328 ± 4 GPa with K = 4.3. EXAFS analysis of the high pressure XAS data p...

High pressure-temperature Raman measurements of H2O melting to 22 GPa and 900 K.

The melting curve of H(2)O has been measured by in situ Raman spectroscopy in an externally heated diamond anvil cell up to 22 GPa and 900 K. The Raman-active OH-stretching bands and the translational modes of H(2)O as well as optical observations are used to directly and reliably detect melting in ice VII. The observed melting temperatures are higher than previously reported x-ray measurements...