Hydrogen Atom Positions in Kaolinite by Neutron Profile Refinement

J. M. Adams
Edward Davies Chemical Laboratories, University College of Wales, Aberystwyth, Dyfed, SY23 1NE, United Kingdom

Abstract: A structure refinement of kaolinite made using the Rietveld neutron profile refinement technique has given non-hydrogen atom positions which were not significantly different from those given by B. B. Zvyagin in 1960. All of the hydrogen atoms have been located; the three inner-surface hydrogen atoms are involved in interlayer hydrogen bonds with lengths of 2.95(4), 2.95(4), and 3.06(4) Å with O-H … O angles of 168(4)°,and 144(4)° and 146(4)° respectively. The inner hydrogen atom is located in a position consistent with that found earlier in dickite and muscovite which are the only dioctahedral layer silicates studied by neutron diffraction to date. The O-H vector makes an angle of 34° with the (001) plane, away from the octahedral sheet, and the projection of the vector on to (001) is at ∼30° to the b axis.

Key Words: Crystal structure • Hydrogen • Kaolinite • Neutron profile refinement • O-H vector • Rietveld method

Clays and Clay Minerals; October 1983 v. 31; no. 5; p. 352-356; DOI: 10.1346/CCMN.1983.0310504
© 1983, The Clay Minerals Society
Clay Minerals Society (www.clays.org)