Publication Date:
2018-06-27
Description:
The low-temperature polymorph β-Ca11B2Si4O22 crystallizes as a monoclinic structure [space group is P21/c, a=14.059(9), b=6.834(5), c=10.597(7) Å, β=100.735(8)°]. The crystal investigated by single-crystal X-ray diffraction was a twin composed of six individuals. The crystal structure is similar to that of mineral spurrite, Ca5(SiO4)2CO3, and can be described as a framework of [CaO5] and [CaO6] polyhedra, the cavities of which are filled with [SiO4] and [BO3] groups. The orientation relationship of twin domains was investigated by electron backscatter diffraction (EBSD). Thermal expansion was studied by high-temperature X-ray powder diffraction. It is slightly anisotropic: α11=10, α22=16, α33=12×10−6°C−1 at 200°C.
Print ISSN:
2194-4946
Electronic ISSN:
2196-7105
Topics:
Geosciences
,
Physics
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