Search

Rare-earth ultraphosphate glasses with nominal R2O3 fractions of 10 and 15 mol% and small ionic radius (large atomic number) R3+ ions (R = Tb, Tm, Lu) are measured by X-ray diffraction at a synchrotron with photons of 119 keV (maximum scattering vector 260 nm− 1). The total correlation functions T(r) show well-resolved R–O and O–O first-neighbor peaks. In contrast to all ultraphosphate RP5O14 crystals and the ultraphosphate glasses of larger R3+ ions, where RO8 polyhedra (mean R–O coordination numbers of ~ 8 for the glasses) are observed, the R3+ ions in glasses with R = Lu, Tm, Tb have mean R–O coordination numbers of ~ 7.5. The R–O first-neighbor peaks extracted from the T(r) functions are compared with those obtained from atomic coordinates of related RP5O14 and RP3O9 crystals. The R–O distances of the ultraphosphate glasses studied are found to fall between those of the two crystals but with tails to the side of longer bonds.

The Basic Energy Sciences Synchrotron Radiation Center Collaborative Access Team has built three independent beamlines, which simultaneously utilize the X-ray radiation from an elliptical multipole wiggler, located at Sector 11 of the Advanced Photon Source. This insertion device produces circularly polarized X-rays on-axis and linearly polarized X-rays above and below the ring plane. The lower linearly polarized radiation is used in the monochromatic 11ID-D station for scattering and spectroscopy experiments in the 5–40 keV range. The on-axis circularly polarized photons are used for magnetic Compton scattering experiments in the 11ID-B station. The upper linearly polarized radiation is utilized by the high-energy diffraction station, 11ID-C. We report here on the beamline optics and experimental station equipment.

The Basic Energy Sciences Synchrotron Radiation Center (BESSRC) has designed and built a diffractometer specialized for high energy synchrotron radiation ( E >60 keV) at the Advanced Photon Source (APS). The diffractometer, which is installed at the elliptical multipole wiggler, uses linearly polarized light (U. Rutt et al., Proc. SPIE 3348 (1998) 132.). The instrument is a triple-axis diffractometer allowing high resolution measurement in two dimensions of the reciprocal space. As opposed to the other diffractometers for high photon energies at HASYLAB (Germany) and ESRF (France) (R. Bouchard et al., 5 (1998) 90; K.-D. Liss et al., J. Synchrotron Rad. 5 (1998) 82), this diffractometer utilizes the vertical scattering plane to take full advantage of the small vertical divergence of the beam and to allow horizontal focusing of the broad beam from the wiggler without disturbing the resolution of the instrument. The instrument is designed to carry heavy sample equipment up to a weight of 200 kg, while maintaining high resolution and low background. First tests have been done to check the overall performance, stability, background and resolution of the diffractometer.

The Basic Energy Sciences Synchrotron Radiation Center Collaborative Access Team (BESSRC-CAT) has built a bending magnet beamline for spectroscopy and scattering experiments at the Advanced Photon Source (APS). The windowless beamline uses a water cooled, double crystal, fixed exit monochromator with Si 1 1 1 crystals as the first optical element. The monochromator is capable of operations from 55° to 3° allowing experiments from approximately 2.5–30 keV. A monochromatc double mirror system located in the white-beam enclosure focuses the beam in the experimental station. When the first mirror is removed energies above the mirror cutoff (∼22 keV) can be used. The 12BM-B user station is equipped for scattering (Huber 6-circle diffractometer) and spectroscopy (optical table, ion chambers and solid state detectors) experiments.