New technique for the observation of x-ray CTR scattering by using an imaging plate detector

A new technique, using an Imaging Plate (IP) detector, was developed for the observation of X-ray crystal truncation rod (CTR) scattering. The use of an IP detector in conjunction with a synchrotron-radiation (SR) source is very effective for the observation of CTR scattering. The advantages and disadvantages of this technique are indicated by examples of the observation of CTR scattering from various samples: a naturally oxidized surface of an Si(111) wafer; MBE-grown GaAs/AlAs/GaAs on GaAs(001) substrate; Al-capped GaAs on an Si(111) substrate; and a cleavage NaCl(001) surface. It is also shown that it is possible to convert the observed intensity of the CTR scattering to an absolute scale if a stationary photograph is taken.Shimura, T. & Harada, J. (1993). J. Appl. Cryst. 26, 151-158, https://doi.org/10.1107/S0021889892010239

DETERMINATION OF THE ELECTRON DENSITY DISTRIBUTION IN TETRAGONAL BaTiOa USING THE MAXIMUM ENTROPY METHOD

ABSTRACT Synchrotron radiation and the maximum entropy method (MEM) were used to study the nature of chemical bonding in tetragonal BaTiOa, and the results were compared to those of cubic SrTiOa. The MEM charge-density map revealed that Ba is essentially ionic, while Ti-0 bond is covalent. A difference in the charge-density distributions of Ti-0 bonds in BaTi and SrTiOa is detected, even though the Ti-0 bonds in these compounds are essentially covalent in nature. The covalency of the Ti-0 bond is, however, weaker in BaTiOa than in SrTiOa. This suggests that BaTi is more ionic. The difference in structure phase transitions between BaTi and SrTiOs can be attributed to the variations in the nature of the Ti-0 bonds in these two compounds

Comment on “Observation of a Distributed Epitaxial Oxide in Thermally Grown SiO2 on Si(001)"

Takayoshi Shimura, Masataka Umeno, Isao Takahashi and Jimpei Harada. Comment on “Observation of a Distributed Epitaxial Oxide in Thermally Grown SiO_2 on Si(001)". Physical Review Letters, 79, 24, 4932. https://doi.org/10.1103/PhysRevLett.79.4932. Copyright 1997 by the American Physical Society

Short-Range Order Parameter of Disordered Cu-29.8 at.% Pd Alloy and the Correlative Microdomain Model

Short-range order diffuse scattering from disordered Cu-29.8 at.% Pd alloy measured by X-ray diffraction is analysed on the basis of the correlative microdomain model proposed by Hashimoto (Acta Cryst. A30 (1974)). By appling a trial and error method, a model was found which reproduces well the short-range order parameters determined by X-ray diffraction experiment, although the model could not be solved in the straightforward way from his expression