Extinction-free electron diffraction refinement of bonding in SrTiO3.
Accurate low-order Fourier coefficients of the crystal potential of SrTiO(3) are measured by quantitative convergent-beam electron diffraction. The accuracy in the corresponding derived X-ray structure factors is about 0.1% for the strong low-order reflections (sin theta/lambda < 0.3 A(-1)). This accuracy is better than for conventional X-ray diffraction and equivalent to the accuracy of the X-ray Pendellosung method. Combination of these structure factors with high-order X-ray diffraction measurements allows accurate bonding information to be obtained from a multipole model fitted to the experimental data. It is shown that Ti-O has a covalent component and that the Sr-O bond is mainly ionic. The role of Ti 3d electrons in Ti-O bonding is also discussed.
Department of Physics, Norwegian University of Science and Technology, Trondeheim, Norway. jesper.friis@material.ntnu.no
Jesper
J
Friis
Bin
B
Jiang
John
J
Spence
Knut
K
Marthinsen
Randi
R
Holmestad