TY - JOUR
T1 - The Structure of High Pressure Ca(OD)2II from Powder Neutron Diffraction
T2 - Relationship to the ZrO2and EuI2Structures
AU - Leinenweber, Kurt
AU - Partin, Dan E.
AU - Schuelke, Udo
AU - O'Keeffe, Michael
AU - Von Dreele, Robert B.
N1 - Funding Information:
The authors acknowledge the support of the NSF Materials Research Group for Synthesis of High Pressure Materials (DMR-91 21570) and Grants EAR-9628678 (K.L.) and DMR 94 24445 (M.O.K.). This work has benefitted from the use of facilities at the Manual Lujan, Jr. Neutron Scattering Center, a national user facility funded as such by the DOE/Office of Basic Energy Sciences.
PY - 1997/9
Y1 - 1997/9
N2 - The "unquenchable" high pressure form of Ca(OD)2[Ca(OH)2II] has been synthesized at 9 GPa and 400°C and recovered to ambient pressure at cryogenic temperatures. The structure was determined from powder neutron diffraction data using the Rietveld technique. The symmetry is monoclinicP21/cwitha=5.3979(4) Å,b=6.0931(4) Å,c=5.9852(4) Å,β=103.581(6)°,Z=4 at 1 atm and 11 K.Rwp=2.8%,Rp=1.9%, reducedχ2=6.6. for 117 variables. The calcium and oxygen substructure is intermediate between that inα-PbO2and that in fluorite; it was previously described as isostructural with baddeleyite (ZrO2), but it is more accurately described as isostructural with EuI2. This structure is distinguished by the presence of a 36anion net parallel to (100). Only one of the two kinds of D atoms in the structure shows appreciable hydrogen bonding to O, with a second neighbor D ... O distance of 1.91 Å, and an O-D ... O angle of 153.2°; the other D atom has 3 second-neighbor oxygens near 2.6 Å away.
AB - The "unquenchable" high pressure form of Ca(OD)2[Ca(OH)2II] has been synthesized at 9 GPa and 400°C and recovered to ambient pressure at cryogenic temperatures. The structure was determined from powder neutron diffraction data using the Rietveld technique. The symmetry is monoclinicP21/cwitha=5.3979(4) Å,b=6.0931(4) Å,c=5.9852(4) Å,β=103.581(6)°,Z=4 at 1 atm and 11 K.Rwp=2.8%,Rp=1.9%, reducedχ2=6.6. for 117 variables. The calcium and oxygen substructure is intermediate between that inα-PbO2and that in fluorite; it was previously described as isostructural with baddeleyite (ZrO2), but it is more accurately described as isostructural with EuI2. This structure is distinguished by the presence of a 36anion net parallel to (100). Only one of the two kinds of D atoms in the structure shows appreciable hydrogen bonding to O, with a second neighbor D ... O distance of 1.91 Å, and an O-D ... O angle of 153.2°; the other D atom has 3 second-neighbor oxygens near 2.6 Å away.
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U2 - 10.1006/jssc.1997.7439
DO - 10.1006/jssc.1997.7439
M3 - Article
AN - SCOPUS:0001691572
SN - 0022-4596
VL - 132
SP - 267
EP - 273
JO - Journal of Solid State Chemistry
JF - Journal of Solid State Chemistry
IS - 2
ER -