Experiments concerning the information depth of electron backscatter diffraction (EBSD) are performed on samples featuring an amorphous wedge on a crystalline substrate and a crystalline wedge on an ...amorphous substrate. The effects of the acceleration voltage and exemplary software settings on the ability to measure through an amorphous layer are presented. Changes in the EBSD-signal could be detected through a ≈142nm thick layer of amorphous Si while orientation measurements could be performed through a ≈116nm thick layer when using a voltage of 30kV. The complexity of the information depth significant to a given EBSD-pattern and the multiple parameters influencing it are discussed. It is suggested that a “core information depth” is significant to high quality patterns while a larger “maximum information depth” becomes relevant when the pattern quality decreases or the sample is inhomogeneous within the information volume, i.e. in the form of partially crystalline materials or crystal layers in the nm scale.
•Experimental evidence of the significant information depth of EBSD is presented.•Effects of the voltage and exemplary software settings are discussed.•Dependence of the significant information depth on the pattern quality is proposed.•The information depth may reach up to 142nm in Si when using a voltage of 30kV.•The information depth depends on the available technology.
Alkali-activated composites of lightweight aggregates (LWAs, with beneficial insulating properties) and alkali-activated foams (AAFs, higher added value products due to their production from waste ...materials at well below 100 °C) allow for the expectation of superior properties if a chemical bonding reaction or mechanical interlocking occurs during production. However, the interfaces between LWAs and an AAF have not been studied in detail so far. Chemical reactions are possible if the LWA contains an amorphous phase which can react with the alkaline activators of the AAF, increase the bonding, and thus, also their mechanical strengths. These, in turn, allow for an improvement of the thermal insulation properties as they enable a further density reduction by incorporating low density aggregates. This work features a first-detailed analyses of the interfaces between the LWAs' expanded polystyrene, perlite, expanded clay and expanded glass, and the alkali-activated foam matrices produced using industrial slags and fly ash. Some are additionally reinforced by fibers. The goal of these materials is to replace cement by alkali-activated waste as it significantly lowers the environmental impact of the produced building components.
Alkali Activated Materials (AAMs) are important potential substitutes for cement in many materials. The AAMs presented here are based on industrial ground granulated blast furnace slag (GGBFS) and ...fly ash (FA). They are tested for their suitability as adhesives for joining concrete, ceramic tiles, a wood-based geopolymer (WGP) and a high density geopolymer (HDGP). After mixing multiple batches and performing preliminary tests of the resulting shrinkage, bending-, compressive- and pull-of-strengths to standard ceramic tiles, selected mixtures are tested for their open time and applied to bond intended substrates. The interfacial zones (ITZ) of an AAM containing additional KOH and the most comparable KOH-free AAM to concrete, ceramic tiles, WPG and HDGP are subsequently characterized in detail using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDXS). Both mechanical interlocking and areas of probable chemical bonding are identified.
This review provides an overview of methods to extract valuable resources from the ash fractions of sewage sludge, municipal solid waste, and wood biomass combustion. The resources addressed here ...include critical raw materials, such as phosphorus, base and precious metals, and rare earth elements for which it is increasingly important to tap into secondary sources in addition to the mining of primary raw materials. The extraction technologies prioritized in this review are based on recycled acids or excess renewable energy to achieve an optimum environmental profile for the extracted resources and provide benefits in the form of local industrial symbioses. The extraction methods cover all scarce and valuable chemical elements contained in the ashes above certain concentration limits. Another important part of this review is defining potential applications for the mineral residues remaining after extraction. Therefore, the aim of this review is to combine the knowledge of resource extraction technology from ashes with possible applications of mineral residues in construction and related sectors to fully close material cycle loops.
Glass-ceramics grown from a glass of the composition Sr2TiSi2.45O8.9 (STS 45) are analyzed by scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). Oriented nucleation with ...the c-axes preferably perpendicular to the surface is detected. A very strong 001-texture is observed after only 10 μm of growth into the bulk, making this the first system in which an orientation preferred during nucleation prevails during growth into the bulk in glass-ceramics. Piezoelectric measurements are performed and d33-values presented and discussed. The obtained results are critically viewed with respect to the two growth models describing Sr2TiSi2O8 growth in glasses.
It has been shown that transparent SrAl
2
O
4
-SrAl
2
Si
2
O
8
ceramics can be synthesized from glasses by complete crystallization. This article features three tectosilicate (SrO/Al
2
O
3
= 1) ...glasses in the system Sr
1−
x
/2
Al
2−
x
Si
x
O
4
with decreasing amounts of SiO
2
(
x
= 0.9, 0.7 and 0.5),
i.e.
with an increasing amount of SrO. The glasses are doped with Eu and produced
via
aerodynamic levitation coupled to laser-heating. Further application of the appropriate single-step heat treatment leads to the complete and congruent crystallization of these glasses
via
surface nucleation and subsequent crystal growth into the bulk. Bulk nucleation does not occur. Analysing the resulting transparent ceramics by scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and X-ray diffraction (XRD) shows that these visually very similar materials exhibit very different microstructures. All three materials show oriented nucleation but the orientations preferred during nucleation never prevail during growth into the bulk where these materials show strong crystallographic textures,
i.e.
they are highly oriented. A previously unknown monoclinic phase with the composition Sr
0.55
Al
1.1
Si
0.9
O
4
is detected at the immediate surface of the corresponding glass after crystallization.
Oriented nucleation is proven in three surface crystallizing tectosilicate (SrO/Al
2
O
3
= 1) glasses in the system Sr
1−
x
/2
Al
2−
x
Si
x
O
4
.
Abstract
The non-isochemical crystallization of glasses leads to glass-ceramics in which the chemical composition of the amorphous matrix differs from that of the parent glass. It is challenging to ...solely analyse the properties of these residual glassy phases because they frequently contain finely dispersed crystals. In this study, the composition of the residual glass matrix after the crystallization of a glass with the mol% composition 50.6 SiO
2
· 20.7 MgO · 20.7 Al
2
O
3
· 5.6 ZrO
2
· 2.4 Y
2
O
3
is analysed by scanning transmission electron microscopy (STEM) including energy dispersive X-ray analysis (EDXS). A batch of the residual glass with the determined composition is subsequently melted and selected properties are analysed. Furthermore, the crystallization behaviour of this residual glass is studied by X-ray diffraction, scanning electron microscopy including electron backscatter diffraction and STEM-EDXS analyses. The residual glass shows sole surface crystallization of indialite and multiple yttrium silicates while bulk nucleation does not occur. This is in contrast to the crystallization behaviour of the parent glass, in which a predominant bulk nucleation of spinel and ZrO
2
is observed. The crystallization of the residual glass probably leads to different crystalline phases when it is in contact to air, rather than when it is enclosed within the microstructure of the parent glass-ceramics.
Attempts to synthesize ZnY2O4 are made via a solid-state reaction in a high-temperature X-ray powder diffraction chamber as well as analyzing Y2O3 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 Y2O3 matrix. Superimposed EBSD patterns of Y2O3 are misindexed as ZnY2O4 during the EBSD scan. The literature concerning ZnY2O4 is critically discussed.
Glass samples with the composition 2SrO·TiO
2
·2.75 SiO
2
were polished, subsequently covered with graphite or alumina powder and finally annealed at 970 °C for 20 h in order to induce surface ...crystallisation. The effect of the surface treatment on the preferred crystal orientations during growth into the bulk is analyzed using X-ray diffraction (XRD) and electron backscatter diffraction (EBSD). Furthermore, the effect of the surface treatment on the piezoelectric d
33
-value is described and referenced to polished samples annealed without previous surface treatment.
The surface crystallisation of Sr
2
TiSi
2
O
8
-type fresnoite from a glass was modified using graphite and alumina powders in order to increase the piezoelectric coefficients. Crystal orientations and piezoelectric properties were analyzed using XRD, SEM, EBSD and a d
33
-meter.
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