X-ray Peak Research Articles

Relationship Between Solar Millimeter and Soft X-Ray Emissions

Abstract The connection between solar radio and soft X-ray emission has earlier been studied at various radio frequencies. For instance, the intensity peak times during solar flares have been compared between these two wavelength regimes. It has been reported that solar radio emission peaks before soft X-ray emission during a flare. However, opposite results have also been presented. In this study, we compare millimetre (8 mm) solar and soft X-ray emissions (0.5–4 Å and 1–8 Å). The radio observations were made at Metsähovi Radio Observatory of Aalto University in Finland between 2015 and 2019. The soft X-ray data were observed with GOES-15 (Geostationary Operational Environmental Satellite). The data show that the solar millimetre emission can peak either before or after soft X-ray peak emission. In this study, we present two different scenarios, which could explain the peaking time differences and behaviour. The first scenario proposes a tight connection between the millimetre (8 mm) and soft X-ray emissions, the second one is for cases where the emission mechanisms are more separate.

X-ray emission from tin (Sn) using the AECS PF-2 plasma focus device

The low energy (2.8 kJ, 25 μF, 15 kV, 120 kA) AECS PF-2 Mather-type plasma focus device operated with nitrogen filling gas is used to study of the high energetic electrons beams effect on the pure tin material inserted on the copper anode tip. The operational gas pressure ranges from 0.2 mbar to 1.2 mbar. For each plasma focus discharge, the current and voltage waveforms are recorded using Rogowski coil and Ohm voltage divider, respectively. Two five channel BPX65 PIN photodiodes X-ray spectrometers (DXS) with appropriate filters are managed to estimate the X-ray yield emitted from the tin (Sn) insert (tin L-series X-ray 3.04–4.474 keV window) at the axial and radial directions. The signals of current, voltage and the temporal evolution of X-rays generated in the AECS PF-2 plasma focus device are simultaneously recorded and then analyzed for different experimental conditions. As the X-ray emission from plasma focus has a shot-to-shot variation, so for each value of gas pressure 3–10 successful shots are performed. The obtained results show that the X-ray yield decreases with increasing pressure from 0.2 to 1.2 mbar. The peak X-ray yield is found to be 0.4 J at the pressure of 0.2 mbar with efficiency ∼0.014% and the lowest values are at the highest pressure of 1.2 mbar. It can be concluded that the X-ray emission from AECS PF-2 plasma focus device depends on the pinch plasma parameters, the generated electron beam properties and the tin insert.

Quantitative analysis of diffraction by liquids using a pink-spectrum X-ray source

A new approach for performing quantitative structure-factor analysis and density measurements of liquids using X-ray diffraction with a pink-spectrum X-ray source is described. The methodology corrects for the pink beam effect by performing a Taylor series expansion of the diffraction signal. The mean density, background scale factor, peak X-ray energy about which the expansion is performed, and the cutoff radius for density measurement are estimated using the derivative-free optimization scheme. The formalism is demonstrated for a simulated radial distribution function for tin. Finally, the proposed methodology is applied to experimental data on shock compressed tin recorded at the Dynamic Compression Sector at the Advanced Photon Source, with derived densities comparing favorably with other experimental results and the equations of state of tin.

Multiwavelength Variability of Sagittarius A* in 2019 July

We report a timing analysis of near-infrared (NIR), X-ray, and submillimeter data during a 3 day coordinated campaign observing Sagittarius A*. Data were collected at 4.5 μm with the Spitzer Space Telescope, 2–8 keV with the Chandra X-ray Observatory, 3–70 keV with NuSTAR, 340 GHz with ALMA, and 2.2 μm with the GRAVITY instrument on the Very Large Telescope Interferometer. Two dates show moderate variability with no significant lags between the submillimeter and the infrared at 99% confidence. A moderately bright NIR flare (F K ∼ 15 mJy) was captured on July 18 simultaneous with an X-ray flare (F 2−10 keV ∼ 0.1 counts s−1) that most likely preceded bright submillimeter flux (F 340 GHz ∼ 5.5 Jy) by about minutes at 99% confidence. The uncertainty in this lag is dominated by the fact that we did not observe the peak of the submillimeter emission. A synchrotron source cooled through adiabatic expansion can describe a rise in the submillimeter once the synchrotron self-Compton NIR and X-ray peaks have faded. This model predicts high GHz and THz fluxes at the time of the NIR/X-ray peak and electron densities well above those implied from average accretion rates for Sgr A*. However, the higher electron density postulated in this scenario would be in agreement with the idea that 2019 was an extraordinary epoch with a heightened accretion rate. Since the NIR and X-ray peaks can also be fit by a nonthermal synchrotron source with lower electron densities, we cannot rule out an unrelated chance coincidence of this bright submillimeter flare with the NIR/X-ray emission.

X-Ray Fine Structure of a Limb Solar Flare Revealed by Insight-HXMT, RHESSI and Fermi

Abstract We conduct a detailed analysis of an M1.3 limb flare occurring on 2017 July 3, which have the X-ray observations recorded by multiple hard X-ray telescopes, including Hard X-ray Modulation Telescope (Insight-HXMT), Ramaty High Energy Solar Spectroscopic Imager (RHESSI), and the Fermi Gamma-ray Space Telescope (Fermi). Joint analysis has also used the extreme ultraviolet (EUV) imaging data from the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamic Observatory. The hard X-ray spectral and imaging evolution suggest a lower corona source, and the non-thermal broken power law distribution has a rather low break energy ∼15 keV. The EUV imaging shows a rather stable plasma configuration before the hard X-ray peak phase, and accompanied by a filament eruption during the hard X-ray flare peak phase. Hard X-ray image reconstruction from RHESSI data only shows one foot point source. We also determined the DEM for the peak phase by SDO/AIA data. The integrated EM beyond 10 MK at foot point onset after the peak phase, while the >10 MK source around reconnection site began to fade. The evolution of EM and hard X-ray source supports lower corona plasma heating after non-thermal energy dissipation. The combination of hard X-ray spectra and images during the limb flare provides the understanding on the interchange of non-thermal and thermal energies, and relation between lower corona heating and the upper corona instability.

Structural Transformations in Cold-Rolled Austenitic Chromium-Nickel Steel Studied by Synchrotron X-Ray Diffraction and Peak Profile Analysis

Structural Transformations in Cold-Rolled Austenitic Chromium-Nickel Steel Studied by Synchrotron X-Ray Diffraction and Peak Profile Analysis

WAXS in-situ study of R-BAPB polyetherimid double-melting behavior

Reactor particles of nascent polyetherimid (PI) R-BAPB powder consist of numerous morphological units of the lamellar type, which have semicrystalline structure. Two endo-peaks at 318 °C and 340 °C were observed in the DSC thermogram of the PI powder. A unique in-situ thermo-WAXS experiment showed no significant difference in X-ray peak profiles when the sample was heated from room temperature up to 330 °C, (the valley between the low- and high-temperature endo-peaks). At that point the WAXS reflections became sharper and much better resolved without a visible crystal cell transformation. It was revealed that the degree of crystallinity dropped near 330 °C and continued decreasing until the complete melting of the sample. The low-temperature endo-peak is associated with melting of numerous small crystallites leading to the sharp amorphization of the sample and to a significant increase in the apparent crystallite size at 330 °C. The high-temperature endo-peak can then be attributed to melting of the larger crystallites formed from the melt during isothermal crystallization at 330 °C. Using WAXS profiles, it was also possible to evaluate the volumetric coefficient of thermal expansion of the crystalline part of the studied polymer as CTEvol = 3.8·10−4 K−1.

Low-Z FIB Grids for Reducing Spurious Fluorescence and X-ray Overlaps

Abstract:Low-Z nanocrystalline diamond (NCD) grids have been developed to reduce spurious fluorescence and avoid X-ray peak overlaps or interferences between the specimen and conventional metal grids. The low-Z NCD grids are non-toxic and safe to handle, conductive, can be subjected to high-temperature heating experiments, and may be used for analytical work in lieu of metal grids. Both a half-grid geometry, which can be used for any lift-out method, or a full-grid geometry that can be used for ex situ lift-out or thin film analyses, can be fabricated and used for experiments.

Influence of Cr2O3 nanoparticles on the structural, optical, thermal and electrical properties of PEO/CMC nanocomposites

In the present paper, different concentrations of chromium oxide (Cr2O3) nanoparticles (≤ 0.6 wt%) were incorporated within PEO/CMC polymer blend to produce nanocomposite films using the casting technique. X-ray diffraction was performed on PEO/CMC-Cr2O3 nanocomposites. The main X-ray peaks of Cr2O3 were observed and defined as cubic structure and orthorhombic shape. The average particle size was calculated by Scherer’s equation in the range between 50 and 60 nm. A decrease of some IR bands after the addition of Cr2O3 nanoparticles was found, which was attributed to the interactions between PEO/CMC and Cr2O3. The effect of Cr2O3 nanoparticles on optical properties such as absorbance and optical energy gap (Eg) was characterized using UV–Vis spectroscopy. The Eg was reduced after the addition of Cr2O3 nanoparticles. The AC conductivity (σac), dielectric constant (ε′), dielectric loss (\({\varepsilon }^{{^{\prime}}{^{\prime}}}\)) and the dielectric modulus (\({\text{M}}^{{^{\prime}}}\text{and }{\text{M}}^{{^{\prime}}{^{\prime}}}\)) were calculated at the frequency range of 0.1 Hz -7 GHz. The increase in direct conductivity (σdc) indicates the resulting free charge density or charge mobility. The calculated values of both ε′ and \({\varepsilon }^{{^{\prime}}{^{\prime}}}\) were decreased with increasing the frequency. The addition of Cr2O3 nanoparticles causes the formation of a charge-transfer complex. The Cole–Cole plot between (\({\text{M}}^{{^{\prime}}}\text{ and }{\text{M}}^{{^{\prime}}{^{\prime}}}\)) shows a semi-circular shape which discuses according to a non‐Debye method.

Dislocation structure and crystallite size distribution in plastically deformed Ti determined by X-ray peak profile analysis

Abstract Ultrafine-grained titanium produced by equal channel angular pressing and subsequent cold rolling is studied by X-ray diffraction. It is found that a texture exists in which the hexagonal basal planes are parallel to the longitudinal axis of the billet. The crystallite size distribution and the dislocation structure are determined by X-ray diffraction peak profile analysis. The median and the variance of the crystallite size distribution are obtained as m = 39 nm and σ = 0.14, respectively. The dislocation model of anisotropic broadening of peak profiles enables to determine the active slip systems. It was found that all three possible hexagonal Burgers vectors of dislocations exist, with the composition of 66% <a> type, 33% <c> type and 1% <c + a> type.

Non-star-forming molecular gas in the Abell 1367 intra-cluster multiphase orphan cloud

We report the detection of CO emission in the recently discovered multiphase isolated gas cloud in the nearby galaxy cluster Abell 1367. The cloud is located about 800 kpc in projection from the center of the cluster and at a projected distance of > 80 kpc from any galaxy. It is the first and the only known isolated “intra-cluster” cloud detected in X-ray, Hα, and CO emission. We found a total of about 2.2 × 108 M⊙ of H2 with the IRAM 30-m telescope in two regions, one associated with the peak of Hα emission and another with the peak of X-ray emission surrounded by weak Hα filaments. The velocity of the molecular gas is offset from the underlying Hα emission by > 100 km s−1 in the region where the X-ray peaks. The molecular gas may account for about 10% of the total cloud’s mass, which is dominated by the hot X-ray component. The previously measured upper limit on the star formation rate in the cloud indicates that the molecular component is in a non-star-forming state, possibly due to a combination of low density of the gas and the observed level of velocity dispersion. The presence of the three gas phases associated with the cloud suggests that gas phase mixing with the surrounding intra-cluster medium is taking place. The possible origin of the orphan cloud is a late evolutionary stage of a ram pressure stripping event. In contrast, the nearby ram pressure stripped galaxy 2MASX J11443212+2006238 is in an early phase of stripping and we detected about 2.4 × 109 M⊙ of H2 in its main body.

Effects of the Ferrits Addition on the Properties of Polyethylene Terephthalate

The products of composites material are very sesetive to many variables, such as manufacturing process, additive materials, …. etc. Filler or additive plays a major role to determine the formation of the properties and behavior of the composites. In this study, polyethylene terephthalate-based compounds were produced and characterized. The work is concerned to prepare samples of Polyethylene terephthalate (PET) - zinc-ferrite (ZnFe2O4) with different addition ratio as zinc-ferrite (1, 2, 5, 10, 15 and 20) wt% obtained from mixing the solution with a hot pressing method applied under optimum conditions. The densities of the composites for all samples were calculated. Through the work the diffusion of zinc-ferrite into the grain of Polyethylene terephthalate has been noted. Structural properties are studied by using X-ray powder pattern, the results of the XRD diffraction analysis showed that the structure for pure PET has four broad peaks at the (2θ=16.46°,17.45°, 22.72°,25.98°). The non-crystalline behavior of the polymer and the ceramic compound indicates the presence of a crystalline phase with a single cubic structure with a space group fd-3m (227)) (a=b=c=8.44 Å, V=601.45 (Å)³). While adding zinc-ferrite to PET in different concentrations to obtain (PET / ZnFe2O4) composites material will increase the intensity of the X-ray peaks, and change the location of the peaks with the addition of zinc-ferrite. It is noted that X-ray diffraction patterns for PET / ZnFe2O4 (20%) indicates that there was no apparent variation of the patterns of pure Zn-ferrite ceramic diffraction which showed that the crystalline structure remains stable in PET / ZnFe2O4. In addition, the electrical properties of the compounds represented by the dielectric constant (real and imaginary), dielectric loss ( tanδ) and the A.C conductivity as a function of a range of frequencies (50Hz-1MHz) have been measured. The results indicated that these properties increase with increasing concentrations of ceramic addition. On the other hand, these properties decrease with increasing frequency due to the change in polarization mechanisms. It has been proven that these prepared superposed materials possess good stability properties in a wide range of frequencies, making these polymeric overlays of wide use in many applications. As for the measurements of Shore D hardness, it has been shown that the hardness of the compounds increases with increasing ceramic concentrations.

Beaming Effect in Fermi Blazars

Abstract Blazars show extreme observational properties that are due to the beaming effect with the jet being close to the line of sight. It was found that the observed luminosity is anticorrelated with the synchrotron peak frequency but the debeamed luminosity and the frequency is positively correlated. In this work, we revisit this correlation for a large sample of 255 blazars from the fourth Fermi catalog with available Doppler factors. Our analysis comes to the following conclusions. (1) The observed radio, X-ray, γ-ray, and synchrotron peak luminosity are all anticorrelated with the peak frequency, but the debeamed luminosity is positively correlated with the debeamed peak frequency. The anticorrelation is due to a selection effect or a beaming effect. (2) The Compton dominance parameter is correlated with both the bolometric luminosity and Doppler factor, implying that the more highly Compton-dominated sources are more luminous. (3) The bolometric luminosity can be represented by the γ-ray luminosity for Fermi blazars.

Ni-incorporated cadmium sulphide quantum dots for solar cell: An evolution to microstructural and linear-nonlinear optical properties

Cadmium sulphide (CdS) compounds have attracted interest due to their applications in opto-electronic devices such as solar cell, sensor, photodiode, etc. The performance of such devices are strongly depends on structure, morphology, and optical properties. Here we report, Ni-incorporated CdS quantum dots(QD) synthesized by conventional chemical co-precipitation method. Ni concentration (0, 2, 4, 6 and 8 wt-%) on Ni-incorporated CdS QD and its microstructural and linear-nonlinear optical properties are extensively investigated. Optical studies derived from UV–ViS. are performed to estimate linear-nonlinear parameters of Ni-incorporated CdS QD by utilizing the absorption and reflection spectra. The optical band gap values decrease from 2.53 to 2.33 eV as Ni content increases. On the other hand, the refractive index values increase with increasing Ni content. Additionally, skin depth, electrical-optical conductivity, and nonlinear parameters are effectively influenced by increasing Ni content in CdS QD.XRD studies confirm that the Ni-incorporated CdS QD exhibits a hexagonal crystal structure with a strong (002) preferential orientation. X-ray peak profile analysis by Scherer method and modified Williamson–Hall method is employed to calculate the crystallite size and lattice parameters such as strain, stress, and energy density of the Ni-incorporated CdS QD. The obtained results indicate that the crystallite size of QD estimated from Scherer and Williamson–Hall methods are correlated and in the range of 2.10–17.89 nm. Energy-dispersive X-ray spectroscopy(EDS) confirms the incorporation of Ni in CdS QD.

Deconstruction of H-bonding and crystallite in directly prepared cellulose nanofibrils after autohydrolysis of eucalyptus

In this study, cellulose nanofibrils (CNFs) were directly prepared after autohydrolysis of eucalyptus raw materials. The effect of different autohydrolysis times on the hydrogen bond structure, micro-structure and properties of CNFs were analyzed by FTIR peak fitting, two-dimensional infrared, TGA, TEM and X-ray diffractometer. The results showed that the autohydrolysis treatments could obviously lead to the sequence of hydrogen bond changes in CNFs as follows: v(weak hydrogen bond) >v(free hydroxyl) >v(O(3)H.O(5)) >v(O(2)H.O(6)) > v(O(6)H.O(3′)), and further impact in crystallite size of CNFs. With the increase of the autohydrolysis strength, the crystallite size of CNFs on the 11¯0 crystal plane could be reduced by up to 26%, but the crystallite size on the 110 crystal plane and the 200 crystal plane increased by 24.5% and 22.6%, respectively. These microstructure changes finally increased the crystallinity index of CNFs, and then resulted in their high thermal stability.

Theoretical and experimental studies on the captured electron population probability of hydrogen-like O and N ions in collision with Al surface

The study of the interaction between highly charged ions and solid surfaces not only has great significance for basic scientific research such as atomic physics, astrophysics, and high energy density physics but also has promising application prospects in biomedicine, nanotechnology, surface analysis, and microelectronics. In this paper, the intermediate Rydberg states formed during highly charged O<sup>7+</sup> and N<sup>6+</sup> ions incident on Al surface are studied theoretically by using the two-state vector model. Both the probability of electron capture into different Rydberg states (<i>n<sub>A</sub></i> = 2 − 7) and the most probable neutralization distances are given. The calculation shows that the larger principal quantum number <i>n<sub>A</sub></i> is relevant to smaller probability. Therefore, the X-rays emitted by O<sup>7+</sup> and N<sup>6+</sup> ions incident on the Al surface come mainly from the de-excitation of the smaller <i>n<sub>A</sub></i> to the ground state. In order to confirm the calculations, we measured the X-ray emission spectra of O<sup>7+</sup> and N<sup>6+</sup> ions in collisions with the Al surface in the energy range of 3-20 keV/q. The experiments were performed at an ECR ion source located in Institute of modern physics. We also calculated the transition energies (n<i>p</i>-1<i>s</i>) from different high Rydberg states to the ground state by using the FAC code. The center of the measured <i>K</i> X-ray peak is close to the calculated transition energy from the principal quantum number n=2 to n=1, it is consistent with our results obtained by the two-state vector model as well. In addition, we found the experimental <i>K</i> X-ray yield for O<sup>7+</sup> ions incidence at lower energy collisions is almost the same with N<sup>6+</sup> ions, but larger at higher energy collisions. When the ion incident kinetic energy is low, the X-ray emission is mainly owing to the decay of “above the surface”hollow atoms. Because of the small difference in the critical distances for the capture of electrons by O<sup>7+</sup> and N<sup>6+</sup> to form hollow atoms, the X-ray yields produced in both cases are almost the same at low energy collisions. In contrast, as increasing the incident energy, the ions have a long-range in the target, so the contribution from the decay of “above the surface” and “below the surface”hollow atoms need to be considered at the same time.

Multiwavelength Analysis of A1240, the Double Radio-relic Merging Galaxy Cluster Embedded in an ∼80 Mpc-long Cosmic Filament

Abstract We present a multiwavelength study of the double radio-relic cluster A1240 at z = 0.195. Our Subaru-based weak-lensing analysis detects three mass clumps forming an ∼4 Mpc filamentary structure elongated in a north–south orientation. The northern ( M 200 = 2.61 − 0.60 + 0.51 × 10 14 M ⊙ ) and middle ( M 200 = 1.09 − 0.43 + 0.34 × 10 14 M ⊙ ) mass clumps separated by ∼1.3 Mpc are associated with A1240 and colocated with the X-ray peaks and cluster galaxy overdensities revealed by Chandra and MMT/Hectospec observations, respectively. The southern mass clump ( M 200 = 1.78 − 0.55 + 0.44 × 10 14 M ⊙ ), ∼1.5 Mpc to the south of the middle clump, coincides with the galaxy overdensity in A1237, the A1240 companion cluster at z = 0.194. Considering the positions, orientations, and polarization fractions of the double radio relics measured by the LOFAR study, we suggest that A1240 is a postmerger binary system in the returning phase with a time since collision of ∼1.7 Gyr. With the SDSS DR16 data analysis, we also find that A1240 is embedded in the much larger scale (∼80 Mpc) filamentary structure whose orientation is in remarkable agreement with the hypothesized merger axis of A1240.

Structural, morphological, thermal, and oxygen-vacancy-related dielectric relaxation behaviors in EuFeO3 perovskite

Europium-ferrite perovskite EuFeO3 was synthesized basing on standard solid state reaction technique. X-ray diffraction analysis revealed the formation of single phase identified to be crystallizing in a Pbnm orthorhombic structure. X-ray peak broadening was conducted to evaluate the crystallite size and lattice strain. Scanning electron microscopy images showed an agglomerated distribution of grain with an average size ranging between 0.47 and 1.11 µm. The presence iron ions in octahedral environment is highlighted Fourier transform infrared (FT-IR) spectroscopy. Dielectric study was performed as a function of both frequencies (1 kHz–1 MHz) and temperatures (298–300 K). The frequency dependence of dielectric properties revealed a quasi-dc process behavior in the material, typical of carrier dominated systems. Two dielectric anomalies were observed, corresponding to the conduction relaxation dominated by the migration of oxygen vacancies. All observed phenomena were pointed by differential scanning calorimetry (DSC) analysis. Optical absorption studies imply the existence of a direct band gap in the sample.

Investigation of the Internal Structure and Gold-thin Layer of the Gilt-bronze Seated Avalokitesvara Bodhisattva at Anseong Cheonryong Temple through the Non-destructive Analysis

Anseong Cheonryongsa, a temple located in Anseong Seoun Mountain, is a part of the second Jogye Order of Korean Buddhism, under the Yongju Temple, and enshrines a gilt-bronze seated Avalokitesvara Bodhisattva. In this study, X-ray fluorescence (XRF) analysis revealed that this statue is composed of Cu-27.2 wt%, Sn-12.6 wt% and Pb-48 wt%. A gamma (γ) ray (Ir-192) image confirmed damage on the backside of the statue, which was later repaired with wood. The XRF analysis and visual observation determined the boundary between the metal and wood in the statue. In addition, results of standard X-ray peak intensity of gold foil and correlation with thickness helped to derive an equation for calculating the thickness of the Avalokitesvara Bodhisattva’s gold foil. It was determined that the gilded chest (21 µm) and face (20.7 µm) of the statue were the thickest sections, the wooden substratum (11.9 µm) was the next-most thick, and the bronze (7.4 µm) was the thinnest layer.

The Effect of Gel-Type Contributions in Lime-Sand Bricks, Alkali-Activated Slags and CEMI/CEMIII Pastes: Implications for Next Generation Concretes.

Lime-sand bricks of different ages were investigated using IR-spectroscopy, thermogravimetry, and X-ray diffraction/scattering. After subtraction of the dominant quartz contribution (80%), the IR spectra show the absorption peaks of the hydrothermally formed binder phases. The spectra also show the alteration of the binder during ageing under atmospheric conditions by the influence of CO2 forming carbonate and a condensed SiO2-gel (secondary gel). The alteration could also be proven in X-ray pattern, obtaining a separation between crystalline CSH and amorphous contributions in the freshly produced lime-sand brick, too. Here, the formation of CSHamorph could be understood as a precursor state (primary gel) to the crystallization of CSH phases. X-ray patterns of aged bodies of alkali-silicate solution activated slags (AAS), CEM-I/CEM-III pastes, and CEM-I concrete indicate that in all cases a similar amorphous CSH-type phase (CSHamorph) was formed, which is responsible for the hardening properties as the glue. The main X-ray peak of CSHamorph obtained using CuKα-radiation with a usual diffractometer is observed between 24° and 35° 2 Theta with maximum at about 29° 2 Theta, whereas it appears much more broadly distributed between 15° and 35° 2 Theta with maximum between 26° and 28° 2 Theta for a geopolymer body prepared using the reaction of alkali-silicate solution and metakaolin (AAMK). This is due to the network formed by siloxo and sialate units in the case of AAMK, given that any crystallization can be ruled out. The origin of increasing mechanical strength during the ageing of AAS mortars must be due to further crosslinking of the preformed siloxo chains. Thermal treatment up to 800 °C leads to a complete loss of any mechanical strength of the CEM pastes due to the destruction of crystalline CSH-phases, whereas geopolymer bodies maintain their strength. Implications for next generation concrete include that cement clinker could be completely replaced by using a using alkali silcate solution technology for gel formation.