Analysis of nanostructure and nanochemistry by ASAXS: Accessing phase composition of oxyfluoride glass ceramics doped with ${\text{Er}}^{3+}/{\text{Yb}}^{3+}$

Analysis of nanostructure and nanochemistry by ASAXS: Accessing phase composition of oxyfluoride glass ceramics doped with ${Er}^{3 +} / {Yb}^{3 +}$

Sylvio Haas, Armin Hoell, Roman Wurth, Christian Rüssel, Peter Boesecke, and Ulla Vainio

Phys. Rev. B 81, 184207 – Published 18 May 2010

Abstract

Here, we describe the analysis of the nanostructure and average chemical compositions of each phase present in an oxyfluoride glass ceramic, which is composed of fluoride nanocrystals and an oxide glass matrix. The overall composition of the oxyfluoride glass ceramic as prepared is $21.1 % {SiO}_{2} 6.5 % B_{2} O_{3} 7.0 % {Al}_{2} O_{3} 21.0 % {PbF}_{2} 14.3 % {CdF}_{2} 11.0 % {YbF}_{3} 0.5 % {ErF}_{3} 11.0 % PbO 7.6 % CdO (mole %)$ . Nanocrystals begin to grow at temperatures above the glass transformation temperature at 678 K as observed by x-ray diffraction. We report results from anomalous small-angle x-ray scattering taken at energies of x-ray absorption edges of Er, Yb, Pb, and Cd. By nonlinear regression of the scattering curves obtained from different edges simultaneously, the nanocrystals were found to be describable as polydisperse spheroids. The length of the smaller axis was found to be $6.4 \pm 1.4 nm$ while the larger axis was found to be $17.7 \pm 3.9 nm$ . By analyzing the scattering contrast as a function of the x-ray energy we found cadmium only in the glass matrix.

Received 1 October 2009

DOI:https://doi.org/10.1103/PhysRevB.81.184207

Authors & Affiliations

Sylvio Haas^* and Armin Hoell

Institute of Applied Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, D-12489 Berlin, Germany

Roman Wurth and Christian Rüssel

Otto-Schott-Institut für Glaschemie, Friedrich-Schiller-Universität Jena, Fraunhoferstraße 6, D-07743 Jena, Germany

Peter Boesecke

European Synchrotron Radiation Facility (ESRF), 6 Rue Jules Horowitz, BP 220, 38043 Grenoble Cedex 9, France

Ulla Vainio

HASYLAB at DESY, Notkestraße 85, D-22607 Hamburg, Germany

^*sylvio.haas@helmholtz-berlin.de

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Vol. 81, Iss. 18 — 1 May 2010

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Figure 1
The energy dependency of the atomic scattering factors (pure elements) of Pb, Er, Yb, and Cd are shown. Close to x-ray absorption edges the values decrease up to 20% of the normal value (atomic number). Energies in the regions shaded in gray are used in the ASAXS experiments.Reuse & Permissions
Figure 2
(Color) Energy dependence of the differential scattering cross sections. (a) Differential scattering cross section of the sample annealed at 678 K for 30 min. For the white layered regions no data have been taken and the isolines of constant differential scattering cross section are linearly interpolated in these regions. The blue line highlights an isoline of constant differential scattering cross section. A change in the isoline in the vicinity of an absorption edge to smaller $q$ values while increasing energy means a decrease in the scattering contrast and vice versa. (b) Measured scattering curves at five different energies close to the $Yb L 3$ edge. The arrows indicate the change of the scattering contrast when the energy increases close to the particular absorption edge.Reuse & Permissions
Figure 3
(Color) TEM visualizations are shown of two similar glass ceramics as the investigated glass ceramic by TEM. The glass (a) contains less ${YbF}_{3}$ while glass (b) contains more ${YbF}_{3}$ than the investigated glass ceramic. In both cases the crystals are locally arranged in a dendritelike structure. In image (a) the approximation by spheroid-shaped particles used for the ASAXS modeling is made clear.Reuse & Permissions
Figure 4
Visualization of the nonlinear regression and obtained size distribution. (a) The comparison of experimental data ( $square = 8525 eV$ and $triangle = 8951 eV$ ) and the fitted theoretical model (solid lines) is shown. The reduced residuals are shown in the bottom part. (b) The volume weighted size distribution for the half axes of the spheroid-shaped particles (solid $line = smaller$ axes and dash line larger axis) is shown.Reuse & Permissions
Figure 5
Energy dependence of the scattering contrast. The circles, squares, and triangles are values obtained from the simultaneous nonlinear regression of all measured scattering curves. The solid line is the simulation using the best-fit parameters with a $Δ E = 1 eV$ .Reuse & Permissions
Figure 6
(Color) A simulation of the energy dependence of the differential scattering cross section is shown. For the calculations the best-fitting parameters were used. The white line marks an isoline of constant differential scattering cross section. The anomalous effects at all x-ray absorption edges (labeled on the right side) are clearly visible.Reuse & Permissions

Physical Review B

covering condensed matter and materials physics

Analysis of nanostructure and nanochemistry by ASAXS: Accessing phase composition of oxyfluoride glass ceramics doped with ${Er}^{3 +} / {Yb}^{3 +}$

Sylvio Haas, Armin Hoell, Roman Wurth, Christian Rüssel, Peter Boesecke, and Ulla Vainio

Phys. Rev. B 81, 184207 – Published 18 May 2010

Abstract

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Physical Review B

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Analysis of nanostructure and nanochemistry by ASAXS: Accessing phase composition of oxyfluoride glass ceramics doped with Er3+/Yb3+

Sylvio Haas, Armin Hoell, Roman Wurth, Christian Rüssel, Peter Boesecke, and Ulla Vainio

Phys. Rev. B 81, 184207 – Published 18 May 2010

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Analysis of nanostructure and nanochemistry by ASAXS: Accessing phase composition of oxyfluoride glass ceramics doped with ${Er}^{3 +} / {Yb}^{3 +}$