IPs, which comprise phtostimulable BaFX : Eu (X=Br, I) phosphor, are coming into use in the field of not only medical diagnostics but also biological and material sciences. Here, after the principle of image acquistion by means of the IP is reviewed, the possible mechanism of the photostimulation of BaFX : Eu, the characteristics of all types of the present IPs, and the changes of the luminescent light emitted from the series of ST-type IPs are presented.
The present status of electron-density studies on high-Tc superconductors is reviewed within the X-ray diffraction method. Difference-Fourier maps of La2-xSrxCuO4, YBa2Cu3O7-x and Tl2CaBa2Cu2O8 have been reported so far. Since the superconductivity always appears associated with copper atoms in distorted perovskite structures, the electron-density distribution around the atoms is discussed on the electronic states. Although severe termination effect of Fourier series was observed in Tl2CaBa2Cu2O8, recent treatments on anharmonic thermal vibrations gradually make it possible to study the electron densities in a superconductive state below Tc.
Crystal structures of YBa2Cu4O8 doped with Co, Fe, Ni and Ca are examined by nears of electron diffraction and high-resolution transmission electron microscopy (HRTEM) . Substitutions of Cu with Co and Fe result in an increase of planar defects due to replacement of (CuO) 2 double chain layers with (CuO) single ones. On the other hand, Ni-substitution has no significant effect on the 1-2-4 structure. As for the arrangement of (CuO) 2 double chain layers and (CuO) single ones, Co-substitution has a trend of ordered arrangements to form 2-4-7 or 3-6-11 structures at higher Co content, wheras Fe-substitution prefers a random one. In the Ca-doped specimens, three kinds of planar defects are observed: the planar defect due to the replacement of (CuO) 2 double chain layer with (CUO) single one, the 90° rotational twinning along the c-direction and the defect due to insertion of an additional Y (or Ca) layer between the two CuO layers of a (CuO) 2 double chain layer.
Surface-selective topographic observations have been performed by extremely asymmetric diffraction, in which the glancing angle of the incident x-rays is near the critical angle of total reflection; this was achieved by using the wavelength tunability of synchrotron radiation. Mechano-chemical polished surfaces of Si (001) and Si (111) wafers were investigated. Strain images arising from the polished surfaces were obtained by adjusting the penetration depth to be several tens of nanometers.
An EXAFS spectrometer with a high-temperature furnace operating in a single or double-crystal mode has been developed for obtaining atomic scale structure of molten materials. The surface of molten materials is always held in the horizontal position by means of vertical-type goniometer with a movable X-ray generator, so that the free surface of melts can be measured.
X-Ray powder diffractometer for synchrotron radiation was designed and constructed at the experimental station BL-4B in Photon Factory, Tsukuba. Main characteristics of the hard ware and soft ware of the diffractometer are : 1) the accurate alignment of the optical axis can be done without special training, 2) the selection of X-ray wavelength in 4 digits can be attained with one calibration in a run of measurements, and 3) the soft ware supplies an easy operation of the diffractometer.