Search results for "Grain Size"
showing 10 items of 131 documents
Medium-Grade Mylonites
2009
The temperature range for the formation of this group of mylonites is approximately 500 to 650 °C. In medium-grade mylonites quartz is usually fully recrystallised, mainly by subgrain rotation, and has grown to a polygonal crystalloblastic fabric of strain free grains with an average grain size exceeding about 50 micrometers.
Valence states of copper in copper ferrite spinels CuxFe3−xO4 (0 < x ≤ 1) fine powders: Evidence of copper insertion
1997
Abstract The oxidation in cation deficient spinels of copper iron spinels Cu x Fe 3− x O 4 (0 x ≤ 1) synthesized by soft chemistry with a grain size x per mole of ferrite, three oxidation phenomena corresponding to Cu + at B-sites (130°C), Fe 2+ at B-sites (180°C) and Cu + at A-sites (240°C) have been found in close relation with the cation-oxygen distance of each oxidizable cation. For nonstoichiometric synthesized spinels Cu x Fe 3− x O 4+ δ with δ x , the presence of additional interstitial Cu + ions has been envisaged. The oxidation temperature of these interstitial ions (> 300°C) is higher than that for Cu + ions at Asites suggesting that interstitial copper ions also essentially resid…
Data for: Accurate representation of the distributions of the 3D Poisson-Voronoi typical cell geometrical features
2019
gvolume.txt contains the grid of points (xgrid.v) and the kernel density estimate (Epanechnikov kernel, cross validation bandwidth h=0.05) of volume of 1,000,000 Poisson-Voronoi typical cells ( intensity parameter lambda=1) evaluated in the grid points (y.v).gsurfacearea.txt contains the grid of points (xgrid.a) and the kernel density estimate (Epanechnikov kernel, cross validation bandwidth h=0.25) of surface area of 1,000,000 Poisson-Voronoi typical cells ( intensity parameter lambda=1) evaluated in the grid points (y.a).gnfaces.txt contains the absolute (nf) and relative frequencies (pf) of number of faces 1,000,000 Poisson-Voronoi typical cells ( intensity parameter lambda=1) THIS DATAS…
Crystalline-Size Dependence of Dual Emission Peak on Hybrid Organic Lead-Iodide Perovskite Films at Low Temperatures
2018
In this work, we have investigated the crystalline-size dependence of optical absorption and photoluminescence emission of CH3NH3PbI3 films, which is necessary to identify the potential practical applications of the gadgets based on perovskite films. This study was carried out at low temperatures to minimize the extra complexity induced by thermal effects. The purpose was to clarify the origin of the dual emission peak previously reported in the literature. We found that the grain size is responsible for the appearance or disappearance of this dual emission on CH3NH3PbI3 at low temperatures, whereas we have inferred that the thickness of the perovskite layer is a much more important factor …
Origin and diversity of testate amoebae shell composition: Example of Bullinularia indica living in Sphagnum capillifolium
2017
Testate amoebae are free-living shelled protists that build a wide range of shells with various sizes, shapes, and compositions. Recent studies showed that xenosomic testate amoebae shells could be indicators of atmospheric particulate matter (PM) deposition. However, no study has yet been conducted to assess the intra-specific mineral, organic, and biologic grain diversity of a single xenosomic species in a natural undisturbed environment. This study aims at providing new information about grain selection to develop the potential use of xenosomic testate amoebae shells as bioindicators of the multiple-origin mineral/organic diversity of their proximal environment. To fulfil these objective…
Influence of HCl pretreatment and organo-mineral complexes on laser diffraction measurement of loess–paleosol-sequences
2016
Abstract The influence of different sample pretreatment methods on grain size distributions in particle size analysis has been subject to controversial discussions. Standard sample preparation typically comprises the disaggregation of aggregated and agglomerated particles into single primary particles, i.e., the organic binding material is oxidized by hydrogen peroxide (H2O2) and the contained carbonates are dissolved by hydrochloric acid (HCl). The aim of this study is to evaluate the effects of HCl treatment on grain size analyses of Late Pleistocene and Holocene loess–paleosol-sequences investigated by a Beckman Coulter LS 13320 laser particle analyzer. For this purpose, samples from two…
Fast Solution Precursor Synthesis of the 2223 Phase: the Role of Lead in the Reaction Pathway
1994
ABSTRACTValuable mechanistic information, about the reaction pathway in the formation of the 2223 phase, has been obtained by the use of a solution synthesis route. The presence of lead in the starting mixture has remarkable effects on the nature and stability of the different intermediates: i) the grain size and morphology of Bi2CuO4 is severely changed, ii) calcium carbonate is partially decomposed to yield the calcium plumbate, iii) the 2201 phase results stabilized against the formation of the collapsed phase Bi17Sr16Cu7O49-δ, iv) the melting point of the intermediate 2212 is lowered by about 10 °C. All these effects, due to lead substitution, contribute to promote the formation of the …
Experimental deformation of deuterated ice in 3D and 2D: identification of grain-scale processes
2015
Major polar ice sheets and ice caps experience cycles of variable flow during different glacial periods and as a response to past warming. The rate and localisation of deformation inside an ice body controls the evolution of ice microstructure and crystallographic fabric. This is critical for interpreting proxy signals for climate change, with deformation overprinting and disrupting stratigraphy deep under ice caps due to the nature of the flow. The final crystallographic fabric in polar ice sheets provides a record of deformation history, which in turn controls the flow properties of ice during further deformation and affects geophysical sensing of ice sheets. For example, identification o…
Study of phase transition in Bi3TiNbO9-BaBi2Nb2O9 ceramics
2016
Abstract The subject of the paper is lead free bismuth layer structure oxides (1-x)Bi3TiNbO9-xBaBi2Nb2O9 (x=0; 1; 2; 3 mol). The influence of Bi3TiNbO9/BaBi2Nb2O9 ratio on dielectric and structural properties was studied in a wide range of temperatures. Change in the ratio causes a decrease in the maximum value of dielectric permittivity and shifts the temperature of ε’max to low values, leading to linear decreasing of average grain size and linear increasing of ceramics density. These results indicate an augment of the packing degree and the participation of pores are significantly decreased with the increase of BaBi2Nb2O9 compound intake. Moreover, for 0.7Bi3TiNbO9-0.3BaBi2Nb2O9 ceramics …
Investigations of Latvian Illite/Kaolinite Clays Irradiated Under Action of Accelerated Electrons
2019
Natural clay is a perspective material for application as sorbents for wastewater treatment as well as for sorption of radionuclides, where the properties of the clays can be changed under influence of ionizing radiation. For application of Latvian illite/kaolinite clays for isotope sorption it is important to characterize the physic-chemical properties of pre-prepared air dried clays. Two fractions of the illite clays were selected. A fraction with grain size 100 μm (SiO2 content 60.9 ± 1.5 wt.%, specific surface area 35 m2/g) and a sand free fraction – 2 μm (SiO2 47.7 ± 1.9 wt.%, specific surface area 38 m2/g). Selected fractions were irradiated with accelerated electrons (5 MeV, ELU-4, S…