EBSD and EDX Analyses of a Multiphase Glass-Ceramic Obtained by Crystallizing an Yttrium Aluminosilicate Glass

Abstract

A glass with the mol % composition 23.82 Y2O3·39.82 Al2O3·28.50 SiO2·2.91AlF3·4.95 ZrO2 doped with 2 mol % CeF3 is crystallized at 1250 °C for 20 h. The crystallized samples are studied using X-ray diffraction (XRD), the SEM-based methods EBSD and EDX, as well as fluorescence microscopy. Six crystalline phases are detected in the residual glass including alumina, YAG, Y-stabilized zirconia (YSZ), and three different yttrium silicates of the composition Y2Si2O7. Chemistry-assisted indexing (ChI) is successfully applied to separate YAG and YSZ in EBSD-scans. YAG displays polygon as well as dendritic growth. Some crystals show both mechanisms at opposite ends, indicating that the growth mechanism is influenced by the chemistry of the surrounding glass matrix.

Surface Crystallization of a MgO/Y2O3/SiO2/Al2O3/ZrO2 Glass: Growth of an Oriented β-Y2Si2O7 Layer and Epitaxial ZrO2

“…Although the problems of analyzing samples containing multiple phases of the composition Y 2 Si 2 O 7 have been illustrated2526272829, XRD-patterns acquired from various glass-ceramic samples annealed in this system are presented in Fig. 1 along with the theoretical patterns of phases indicated in this system by EBSD-analyses which will be presented later.…”

“…By analogy, many compositions in the Y 2 O 3 /Al 2 O 3 /SiO 2 system show the crystallization of various crystallographically different YS phases and yttrium aluminum garnet (YAG)26272829. At least seven YS phases have been described in the literature so far3031 and a small overview of the literature was recently presented in ref.…”

“…However, β-, δ- and ε-YS have been shown to simultaneously occur in some YAG-containing glass-ceramics26272829 while α-YS was additionally observed in glass-ceramics grown from an SiO 2 -MgO-Al 2 O 3 -ZrO 2 -Y 2 O 3 glass with a higher Al content25. These results also illustrated that an X-ray diffraction (XRD)-analysis of these phases is problematic if they occur simultaneously due to multiple peak super positions, a problem illustrated in detail in ref.…”

Oriented Nucleation of both Ge-Fresnoite and Benitoite/BaGe4O9 during the Surface Crystallisation of Glass Studied by Electron Backscatter Diffraction

“…for the separation of cubic and hexagonal ZnS44, or by chemistry assisted indexing (ChI) which combines EBSD with energy dispersive X-ray spectroscopy (EDS) to enable a chemistry based phase attribution to a data point, e.g. used to separate the cubic phases YAG and yttrium stabilized zirconia45. The first approach has been unsuccessful so far and ChI is unsuitable for the given problem because both phases contain Ba and the only suitable separator of the phases would be via the Ti content.…”

Analysis of the cordierite X-phase and phase transformation by electron backscatter diffraction (EBSD)

“…Thus it seems reasonable to assume that the quantity of indialite is below the detection limit of XRD in this sample, explaining why it was never detected via XRD under comparable conditions in the past, a similar problem to that posed for the X-ray analysis of the X-phase. It must be noted that XRD recently failed to detect an Alenriched crystalline phase forming structures larger than 10 μm in a YAG-containing glass ceramic [25]. This puzzling effect raises the question whether XRD can be utilized as actual proof for the absence of a phase or the amorphicity of a sample.…”