Crystal structure of sibirskite (CaHB03) by Monte Carlo simulation and Rietveld refinement
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Affiliation |
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| Miura et al , Hiroyoki | Department of Natural History Sciences | Graduate School o/Science, Hokkaido University, Sapporo 060-0810, Japan | |
DESCRIPTOR(S)
The crystal structure of sibirskite (CaH80») was solved by the Monte Carlo simulation using powder X-ray diffraction data and confinned by the Rietveld refinement. The mineral sibirskite is monoclinic with space group P21/a and cell constants of a = 8.643(6), b = 9.523(2), c = 3.567(3) A, and f3 = 119.23(3)° The unit cell consists of independent atoms such as calcium, boron, hydrogen, and three oxygen atoms. The calcium atom is surrounded by six oxygen atoms in an octahedral coordination, and a symmetrical pair of edge-shared Ca06 octahedra forming a double chain elongates the crystallographic c axis. The Ca06 double chains are not directly connected to each other. The 80) triangles are linked to one vertical and two shared oxygen atoms in three Ca06 double chains to form the sibirskite structure. Sibirskite is isostructural with nahcolite (NaHCO»), which consists of a06 double chains and CO) triangles.