Abstract:The crystallization behavior of a glass with the composition 54.7 SiO2·10.9 Al2O3·15.0 MgO·3.4 ZrO2·16.0 Y2O3 is studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) including electron backscatter diffraction (EBSD) and (scanning) transmission electron microscopy [(S)TEM] including energy-dispersive X-ray spectrometry (EDXS). This glass shows the sole surface crystallization of four different yttrium silicates of the composition Y2Si2O7 (YS). The almost simultaneous but independent nucleat… Show more
“…Oriented nucleation has been described to occur in glass-ceramics containing Ba-fresnoite, , Sr-fresnoite, , or Ge-fresnoite . It has also been detected in other systems during the surface crystallization of BaAl 2 B 2 O 7 , , diopside, Sr 1– x /2 Al 2– x Si x O 4 ( x = 0.9, 0.7, and 0.5), walstromite, probably ε-Y 2 Si 2 O 7 , as well as yttrium stabilized ZrO 2 and after the crystallization of mullite at the surface of a glass melt during cooling . The arguments for oriented nucleation have been presented in detail in ref .…”
Glasses of the mol composition 2
BaO·TiO2·2
SiO2 + x SiO2 (with x = 0.0, 0.1, 0.2, 0.5, 0.75, 1.5, 2.0, and 3.0 mol) were
prepared, polished, and crystallized at 810 °C for 5 h or more.
All glasses showed the sole crystallization of Ba-fresnoite (Ba2TiSi2O8). The crystal orientations at
the immediate surfaces were analyzed by EBSD and showed that all glasses
exhibit a nonrandom orientation distribution, i.e., oriented nucleation
at the surface. While the glasses with x = 0.0, 0.1,
and 0.2 show rather broad orientation preferences in the form of c-axes tilted from the surface by roughly 10–50°,
the glasses with x = 1.5 or higher show discrete
textures where specific crystal orientations are significantly preferred
with orientation spreads of less than ±15°. While the glasses
with x = 0 and 0.1 show polygon crystals at the surface
and in the bulk, dendritic crystals are observed in the bulk of all
other analyzed compositions. Phase separation solely occurred in the
glass with x = 1.5 during the applied heat treatments.
“…Oriented nucleation has been described to occur in glass-ceramics containing Ba-fresnoite, , Sr-fresnoite, , or Ge-fresnoite . It has also been detected in other systems during the surface crystallization of BaAl 2 B 2 O 7 , , diopside, Sr 1– x /2 Al 2– x Si x O 4 ( x = 0.9, 0.7, and 0.5), walstromite, probably ε-Y 2 Si 2 O 7 , as well as yttrium stabilized ZrO 2 and after the crystallization of mullite at the surface of a glass melt during cooling . The arguments for oriented nucleation have been presented in detail in ref .…”
Glasses of the mol composition 2
BaO·TiO2·2
SiO2 + x SiO2 (with x = 0.0, 0.1, 0.2, 0.5, 0.75, 1.5, 2.0, and 3.0 mol) were
prepared, polished, and crystallized at 810 °C for 5 h or more.
All glasses showed the sole crystallization of Ba-fresnoite (Ba2TiSi2O8). The crystal orientations at
the immediate surfaces were analyzed by EBSD and showed that all glasses
exhibit a nonrandom orientation distribution, i.e., oriented nucleation
at the surface. While the glasses with x = 0.0, 0.1,
and 0.2 show rather broad orientation preferences in the form of c-axes tilted from the surface by roughly 10–50°,
the glasses with x = 1.5 or higher show discrete
textures where specific crystal orientations are significantly preferred
with orientation spreads of less than ±15°. While the glasses
with x = 0 and 0.1 show polygon crystals at the surface
and in the bulk, dendritic crystals are observed in the bulk of all
other analyzed compositions. Phase separation solely occurred in the
glass with x = 1.5 during the applied heat treatments.
“…Most of the Bi 2 Al 4 O 9 -domains in Fig. 7c share a common orientation with a tolerance of 5°, indicating that they originate from a common nucleus and grew along the existing channels of residual glass, similar to the behaviour of cordierite after the crystallisation of multiple yttrium silicates 29 or fresnoite after the crystallisation of BaTiO 3 30 in glasses. An epitaxial relationship similar to that observed between Bi 4 Ti 3 O 12 and Bi 2 SiO 5 in related glass-ceramics 24 could not be discerned.Figure 7( a ) SEM-micrograph showing the fine crystallisation at the bottom edge of glass-ceramic B.…”
A glass melt with the composition 24Bi2O3/40TiO2/10SiO2/10Nd2O3/16 Al2O3 was prepared and rapidly quenched between two copper blocks (sample A). A part of this glass was subsequently crystallised at 800 °C for 8 h (sample B). For the preparation of another two samples, the melt was slowly cooled on a cooper plate (sample C) or cast into a graphite mould and subsequently thermally treated at 300 °C for 3 h (sample D). As shown by X-ray diffraction (XRD) and scanning electron microscopy (SEM) including energy dispersive X-ray spectroscopy (EDXS) and electron backscatter diffraction (EBSD) measurements, the rapidly cooled samples contained notable amounts of uncrystallised glassy phase next to the Aurivillius phase Bi4Ti3O12. The latter occurred in higher concentrations in all other samples and formed oriented layers. Minor concentrations of Bi2Al4O9 and Al2O3 were also detected in the microstructure.
“… 15 , 16 EBSD can be used to identify the phases of low content in crystalline microstructures, which fail to be detected by X-ray diffraction. 10 , 17 − 20 However, EBSD needs a homogeneous crystal lattice to function as a diffraction lattice and enable the formation of Kikuchi bands. Hence, EBSD is probably not suited to analyze the thin rods and small particles resulting from the previously proposed sol–gel process.…”
Section: Introductionmentioning
confidence: 99%
“…As the information volume of EDXS usually exceeds an area of 1 μm in diameter (the applied acceleration voltage is not stated in ref , EDXS is not suited to resolve the composition of the proposed nanometer-sized grains. Microstructures containing multiple phases can appear homogeneous in an EDXS map , even if the crystals approach the micrometer scale in size; see, e.g. , the distribution of Mg in Figure 16d of ref .…”
Attempts to synthesize ZnY
2
O
4
are made via
a solid-state reaction in a high-temperature X-ray powder diffraction
chamber as well as analyzing Y
2
O
3
sinter ceramics
pressure infiltrated by ZnO in a scanning electron microscope using
energy-dispersive X-ray spectroscopy and electron backscatter diffraction
(EBSD). The microstructure of the sinter ceramic is composed of ZnO
grains dispersed in an Y
2
O
3
matrix. Superimposed
EBSD patterns of Y
2
O
3
are misindexed as ZnY
2
O
4
during the EBSD scan. The literature concerning
ZnY
2
O
4
is critically discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
