scholarly journals Raman spectroscopy, mobility size and radiative emissions data for soot formed at increasing temperature and equivalence ratio in flames hotter than conventional combustion applications

Data in Brief ◽  
2021 ◽  
pp. 107064
Author(s):  
Shruthi Dasappa ◽  
Joaquin Camacho
Keyword(s):  
Raman Spectroscopy ◽  
Equivalence Ratio ◽  
Conventional Combustion ◽  
Increasing Temperature

scholarly journals Raman Spectroscopy and Statistical Analysis of the Silicate Species and Group Connectivity in Cesium Silicate Glass Forming System

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
Armenak Osipov ◽  
Leyla Osipova ◽  
Rimma Zainullina
Keyword(s):  
Experimental Data ◽  
Raman Spectroscopy ◽  
Statistical Analysis ◽  
Raman Spectra ◽  
Dynamic Equilibrium ◽  
Structural Units ◽  
Melt Temperature ◽  
Deconvolution Analysis ◽  
Glass Forming ◽  
Increasing Temperature

The Raman spectra of x%Cs2O-(100 − x)%SiO2 (x=17, 22, 27, 33, and 37 mol%) glasses and melts were measured in the temperature range of 293 to 1553 K. The concentrations of the Qn species were calculated as a function of the composition and temperature based on the deconvolution analysis of the spectra. It was found that a dynamic equilibrium among structural units in the melts with x>17 mol% can be described by disproportionation reaction Q3⇔Q4+Q2. The enthalpy of this reaction was found to be equal to 32 ± 6, 43 ± 8, 56 ± 10, and 52 ± 9 for x=22, 27, 33, and 37 mol%, respectively. The nonideal entropy of mixing (ΔSmix) depends on the melt temperature and increases almost linearly with increasing temperature. The Qn, Q2–Q2, and Qn,ijkl distributions with x ranging from 0 to 55 mol% were modeled using experimental data for the concentrations of the Qn units.

Carbon ordering in an aseismic shear zone: implications for crustal weakening and Raman spectroscopy

2020 ◽  
Author(s):  
Lauren Kedar ◽  
Clare Bond ◽  
David Muirhead
Keyword(s):  
Raman Spectroscopy ◽  
Organic Carbon ◽  
Shear Zone ◽  
Experimental Studies ◽  
Carbonaceous Material ◽  
Shear Zones ◽  
Lower Limbs ◽  
Strain Partitioning ◽  
Increasing Temperature ◽  
Two Peaks

<p>Multi-layered stratigraphic sequences present ample opportunity for the study of strain localization and its complexities. By constraining mechanisms of crustal weakening, it is possible to gain a sounder understanding of the dynamic evolution of the Earth’s crust, especially when applied to realistic, field-based scenarios. One such mechanism is that of strain-related carbon ordering. This is the process whereby the amorphous nanostructure of fossilized organic matter contained within the rock is progressively organized towards a more sheet-like structure, similar to that of graphite. One common method of studying this process is through Raman spectroscopy. This is a non-destructive tool which makes use of the relative positions and intensities of two key spectral peaks, where one peak represents graphitic carbon and the other disordered (or amorphous) carbon. The intensity ratio between these two peaks suggests the degree to which the carbon has progressed from its original kerogen-like structure towards that of graphite. This progression can be due to increasing temperature or increasing strain, and until now, these two contributory factors have been difficult to separate, particularly in field examples.</p><p>Previous field-based studies have focused on carbon ordering on fault planes, while experimental studies have monitored the effects of strain-related ordering in organic carbon on both fault surfaces and more distributed shear zones. These studies confirmed the occurrence of strain-related ordering at seismic rates, particularly in the form of graphitization of carbon. However, these experiments showed the effects of strain-related ordering at aseismic rates to be limited when distributed shear zones were considered, in part due to the geological timescales required to emulate true conditions.</p><p>In this study, Raman spectroscopy is used to compare the relative nanostructural order of organic carbon within a recumbent isoclinal fold formed of interbedded limestones and marls. The central, overturned fold limb forms a 170m wide, 1km long aseismic shear zone, with evidence of increased strain recorded in calcite grains relative to the upper and lower limbs. Raman spectroscopy intensity ratios (I[d]/I[g]) are compared across the fold, showing a marked 23% decrease in the overturned limb. Such a decrease in I[d]/I[g] suggests increased carbon ordering within the overturned limb, which in combination with evidence for increased strain in calcite, suggests that the carbon ordering here is derived directly from strain-related ordering. This has important implications. We infer, from previous studies, that strain-related carbon ordering encourages further strain partitioning in carbonaceous material, and may enhance zones of weakness in the rock. This ordering in aseismic shear zones has so far been unreported in nature, and so our field-based results are significant in supporting previous experimental evidence for this phenomenon. Our results also have implications for understanding dynamic crustal evolution, and will play an important role in the development of Raman thermobarometry, especially since current methods do not distinguish between strain-related and temperature-related ordering.</p>

Thermal Conductivity of Boron Carbides

1987 ◽  
Vol 97 ◽  
Author(s):  
Marvin Moss
Keyword(s):  
Electron Microscopy ◽  
Thermal Conductivity ◽  
Scanning Electron Microscopy ◽  
Raman Spectroscopy ◽  
Temperature Dependence ◽  
Rutherford Backscattering ◽  
Rutherford Backscattering Spectroscopy ◽  
Theoretical Density ◽  
Increasing Temperature ◽  
Scanning Electron

ABSTRACTThe thermal conductivity, k, of boron carbides of various B/C ratios, two modes of preparation – hot pressed and carbothermic, and two isotopic variants of boron – 11B and normal boron 10.81B, was measured from 300 to 1023 K. The density and composition of the samples were reflected in the magnitude and temperature dependence of k, and were investigated further with scanning electron microscopy, Rutherford backscattering spectroscopy, and Raman spectroscopy. While lower than theoretical density in B4C reduces k, the characteristic monotonic decline of k with increasing temperature is retained. This k-vs.-T behavior distinguishes B4C from material with larger B/C ratios for which the temperature dependence is essentially nil.

Applying Raman Spectroscopy to Modern and Palaeocharcoals Associated with Wildfire Activity

2020 ◽  
Author(s):  
Thomas Theurer ◽  
David Muirhead ◽  
David Jolley
Keyword(s):  
Raman Spectroscopy ◽  
Vitrinite Reflectance ◽  
Climatic Conditions ◽  
Thermal Maturity ◽  
Deep Time ◽  
New Approach ◽  
Composition And Structure ◽  
Determining Factors ◽  
Increasing Temperature ◽  
The Impact

<p>Evidence of wildfire activity in deep time is preserved in the rock record as fossilised charcoal. Modern wildfire temperature is often a function of fuel type, structure and availability. These three factors are reliant upon climatic conditions and offer a potential insight into palaeoenvironmental conditions through geothermometric analysis of preserved charcoals. Much like the analysis of vitrinite reflectance as an assessor of thermal maturity, similar methodology has been applied historically to charcoal in order to obtain palaeowildfire temperatures.  Raman spectroscopy has similarly been applied to organic material as an identifier of thermal maturity, via the analysis of carbon microstructure changes with increasing temperature – however very little palaeocharcoal has been analysed via Raman spectroscopy, with no apparent application to palaeowildfire geothermometry. Through the application of Raman spectroscopy, we present the first comparison of modern pyrolyzed plant material with spectra of early Danian palaeocharcoals, associated with wildfire activity. These results indicate that Raman spectroscopy of modern wildfire charcoal facilitates a correlation between charcoal microstructure change and temperature of formation. This in turn has enabled comparison with palaeocharcoal, and the generation of reliable wildfire geothermometry. With this new methodology, we intend to further the understanding of (1) changes in palaeowildfire regimes and intensity through time (2) the interaction between climate, plant community composition and structure, and palaeowildfires  (3) correlation and comparison with existing palaeowildfire interpretive approaches. Further analysis and experimentation is required to identify the impact of fire determining factors on observed spectra to target the new approach towards interpreting current and future wildfire behaviour under climatic stress. </p>

scholarly journals On the Structural Peculiarities of Self-Reinforced Composite Materials Based on UHMWPE Fibers

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1408
Author(s):  
Dmitry Zherebtsov ◽  
Dilyus Chukov ◽  
Isabelle Royaud ◽  
Marc Ponçot ◽  
Ilya Larin ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Compaction Pressure ◽  
Polarized Light ◽  
Tensile Tests ◽  
X Ray ◽  
Hot Compaction ◽  
The Matrix ◽  
Uhmwpe Fibers ◽  
Increasing Temperature

The structure of self-reinforced composites (SRCs) based on ultra-high molecular weight polyethylene (UHMWPE) was studied by means of Wide-Angle X-ray Scattering (WAXS), X-ray tomography, Raman spectroscopy, Scanning Electron Microscopy (SEM) and in situ tensile testing in combination with advanced processing tools to determine the correlation between the processing conditions, on one hand, and the molecular structure and mechanical properties, on the other. SRCs were fabricated by hot compaction of UHMWPE fibers at different pressure and temperature combinations without addition of polymer matrix or softener. It was found by WAXS that higher compaction temperatures led to more extensive melting of fibers with the corresponding reduction of the Herman’s factor reflecting the degree of molecular orientation, while the increase of hot compaction pressure suppressed the melting of fibers within SRCs at a given temperature. X-ray tomography proved the absence of porosity while polarized light Raman spectroscopy measurements for both longitudinal and perpendicular fiber orientations showed qualitatively the anisotropy of SRC samples. SEM revealed that the matrix was formed by interlayers of molten polymer entrapped between fibers in SRCs. Moreover, in situ tensile tests demonstrated the increase of Young’s modulus and tensile strength with increasing temperature.

Vibrational spectral studies of solutions at elevated temperatures and pressures. 11. A Raman spectral study of aqueous iron(III) chloride solutions between 25 and 300 °C

1989 ◽  
Vol 67 (3) ◽  
pp. 517-524 ◽  
Author(s):  
Katsuo Murata ◽  
Donald E. Irish ◽  
Gerald E. Toogood
Keyword(s):  
Raman Spectroscopy ◽  
Dielectric Constant ◽  
Dominant Species ◽  
Elevated Temperatures ◽  
Spectral Studies ◽  
Iron Species ◽  
Chloride Solutions ◽  
Increasing Temperature ◽  
Raman Spectral ◽  
Temperature Factors

The Raman spectra of acidified aqueous iron(III) chloride solutions have been measured between 25 and 300 °C. When Fe3+ concentrations are in the range 0.75 to 1.0 mol kg−1 and Cl−/Fe3+ ratios, R, in the range 3 to 9.5, the dominant species at 25 °C is trans-[Fe(H2O)4Cl2]+; at 300 °C the sole iron-containing species is tetrahedral [Formula: see text]. Conversion of [Fe(H2O)4Cl2]+ into [Formula: see text] appears not to involve intermediate iron species. In the presence of excess chloride the reaction [Formula: see text] is presumed to occur; ΔH for this reaction has been estimated as +65 ± 8 kJ mol−1. In addition to increasing temperature, factors which favour [Formula: see text] over other iron species include increasing acidity, increasing R, and decreasing dielectric constant. Keywords: high temperature aqueous solutions, iron(III) chloride, Raman spectroscopy.

scholarly journals Raman spectroscopy, mobility size and radiative emissions data for soot formed at increasing temperature and equivalence ratio in flames hotter than conventional combustion applications

2021 ◽  
Author(s):  
Shruthi Dasappa ◽  
Joaquin Camacho
Keyword(s):  
Particle Size ◽  
Equivalence Ratio ◽  
Carbon Nanomaterials ◽  
Soot Formation ◽  
Flame Temperature ◽  
Growth Environment ◽  
Conventional Combustion ◽  
Structural Order ◽  
Color Ratio ◽  
Research Article

The dataset presented in this article is linked to the research article titled “Evolution in size and structural order for incipient soot formed at flame temperatures greater than 2100 K” [1]. The research article discusses the systematic evolution of flame formed carbon in premixed stagnation flames with flame temperatures hotter than conventional combustion applications. The effect of the growth environment on particle size, structure, composition and properties are studied. The flame temperature (1950 K < Tf,max < 2250 K) and equivalence ratio (Φ = 2.4, 2.5, and 2.6) are methodically varied to analyze impact on insipient soot while maintaining a comparable particle residence time (tp ~ 15 ms). This article presents the data acquired for this systematic study. The data presented herein provides fundamental observations suitable for development of soot formation theory and modeling. Characterization of material properties and morphology are also relevant to potential applications of functional carbon nanomaterials. Raman spectra are measured for carbon films deposited from the flames, soot particle size distributions are obtained by aerosol sampling from the flames and soot radiative emissions are measured in-situ by color-ratio pyrometry. Deconvolution of Raman peaks is carried out to extract information on carbon bonding and structural order. Flame temperature is extracted from the measured color-ratio field making assumptions for the soot optical dispersion exponent.

scholarly journals Structural Details of BaTiO3 Nano-Powders Deduced from the Anisotropic XRD Peak Broadening

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1121
Author(s):  
Iuliana Pasuk ◽  
Florentina Neațu ◽  
Ștefan Neațu ◽  
Mihaela Florea ◽  
Cosmin M. Istrate ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Reaction Times ◽  
Surface Relaxation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Peak Broadening ◽  
Transmission Electron ◽  
Cubic Crystallites ◽  
Increasing Temperature ◽  
Peak Widths

In this study, nano-BaTiO3 (BTO) powders were obtained via the solvothermal method at different reaction times and were investigated using transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy. The results were compared with those obtained for a larger crystallite size BTO powder (BTO-m). The sizes of the cuboid crystallites (as determined by XRD and TEM) ranged from about 18 to 24 nm, depending on the reaction time. The evolution with temperature of the structure parameters of nano-BTO was monitored by means of X-ray diffraction and Raman spectroscopy and no signs of phase transition were found up to 170 °C. Careful monitoring of the dependence of the XRD peak widths on the hkl indices showed that the effect of the cubic crystallite shape upon the XRD peak widths was buried by the effect of hidden tetragonal line splits and by anisotropic microstrain. The good correlation of the line widths with the tetragonal split amplitudes, observed especially for BTO-m above the transition temperature, indicates tetragonal deformations, as also revealed by Raman spectroscopy. The large anisotropic microstrain shown by the nano-powders, which had a maximum value in the <100> directions, was considered evidence of the phenomenon of surface relaxation of cubic crystallites edged by {100} faces. The observed behavior of the nano-BTO structures with increasing temperature may suggest a correlation between the surface relaxation and tetragonal deformation in the nano-cubes. The experimental results for both nano-BTO and mezoscale-BTO are in agreement with the core-shell model.

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