Crystal Structure and Electrical Property of Calcium under Very High Pressure

Exotic behavior and crystal structures of calcium under pressure.

Experimental studies established that calcium undergoes several counterintuitive transitions under pressure: fcc --> bcc --> simple cubic --> Ca-IV --> Ca-V, and becomes a good superconductor in the simple cubic and higher-pressure phases. Here, using ab initio evolutionary simulations, we explore the behavior of Ca under pressure and find a number of new phases. Our structural sequence differs...

Protein Crystal Growth Under High Pressure

High-pressure Synthesis and Crystal Structure of the Borate Sc3B5O12

The rare-earth borate Sc3B5O12 was synthesized under high-pressure / high-temperature conditions of 6 GPa and 1100 ◦C in a Walker-type multianvil apparatus. The single-crystal structure determination revealed an isotypy to RE3B5O12 (RE = Er–Lu). Sc3B5O12 crystallizes in the rare space group Pmna (Z = 4) with the parameters a = 1245.4(3), b = 443.46(9), c = 1222.1(2) pm, V = 0.675(1) nm3, R1 = 0...

Compressibility and crystal structure of sillimanite, Al2SiO5, at high pressure

R.T. Downs Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA Abstract The unit-cell dimensions and crystal structure of sillimanite at various pressures up to 5.29 GPa have been refined from single-crystal X-ray diffraction data. As pressure increases, a and b decrease linearly, whereas c decreases nonlinearly with a slightly positive curvature. The axial compression ...

High-pressure phases of CaCO3: Crystal structure prediction and experiment

Post-aragonite phase of CaCO3, experimentally known to be stable above 40 GPa [S. Ono, T. Kikegawa, Y. Ohishi, J. Tsuchiya, Post-aragonite phase transformation in CaCO3 at 40 GPa, Am. Mineral. 90 (2005) 667–671], is believed to be a major carboncontaining mineral in the Earth’s mantle. Crystal structure of this mineral phase could not be solved using experimental data or traditional theoretical...