scholarly journals Oxidative Thermal Conversion of Hydrothermal Derived Precursors toward the Mixed-Metal Cobaltite Spinel Oxides (ZnCo2O4 and NiCo2O4): In-Situ Investigation by Synchrotron-Radiation XRD and XAS Techniques

Crystals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1256
Author(s):  
Wanchai Deeloed ◽  
Yuranan Hanlumyuang ◽  
Wanwisa Limphirat ◽  
Songwut Suramitr ◽  
Kantapat Chansaenpak ◽  
...  
Keyword(s):  
Chemical Properties ◽  
Oxide Phase ◽  
Site Preference ◽  
Spinel Oxide ◽  
Essential Information ◽  
Mixed Metal ◽  
In Situ Investigation ◽  
Spinel Oxides ◽  
Cobaltite Spinel

In-situ investigations of structural transitions during the thermal-oxidative event of mixed-metal spinel oxide precursors, the so-called nickel- (NCO) and zinc-containing (ZCO) cobaltite spinel precursors, were investigated to understand the formations of the derived NiCo2O4 and ZnCo2O4 spinel oxides, respectively. In-situ XRD investigation revealed that emerged temperatures for spinel oxide phase were between 325 and 400 °C, depending on the cationic substituent. It indicated that the emerged temperature correlated with the absolute octahedral site preference energy (OSPE) of those cations that participated in the development of the spinel framework. Moreover, the incorporated nickel and zinc in the precursors was beneficial for inhibiting the occurrence of the undesired CoO phase. Time-resolved X-ray absorption spectroscopic (TRXAS) data suggested the local structure rearrangement of nickel and zinc throughout the calcination process, which differed from the behavior of single-metal cobalt system. The essential information reported herein provides a benefit to control the cationic distribution within spinel materials, leading to the tunable physical and chemical properties.

scholarly journals Investigating the Effect of Gypsum Powder on Chemical Constituents of Soil and Selected Crops, Adigudem, Tigray, Ethiopia

2021 ◽  
Vol 13 (1) ◽  
pp. 164-176
Author(s):  
Berhe Hailu ◽  
Samuel Estifanos
Keyword(s):  
Chemical Constituents ◽  
Control Sample ◽  
Chemical Properties ◽  
Chemical Constituent ◽  
Major Elements ◽  
Plant Parts ◽  
In Situ Investigation ◽  
Mekelle University ◽  
Properties Of Soil

This paper investigates the effects of gypsum powder from the gypsum plant in Adigudem on chemical properties of soil as well as the yield of two major crops, wheat (Triticum aestivum) and barley (Hordeum vulgare). Three mixes of 10kg of soil with 0%, 10%, 30%, and 50% proportion of gypsum powder were used for pot experiments under glasshouse conditions at Mekelle University. One bulk soil sample was collected from a spot at 4 km from the eastern side of the plant. The chemical concentration of major elements Ca, K, Na, Mg, and Mn, and trace elements, Cd, Zn, Cu, Pb, Cr, and Fe in soil and plant parts were determined using an Atomic absorption spectrometer as well as NO3, PO4 and SO4 using UV-spectrometer. The results suggest that the gypsum powder enhances metals and anion content in soil and in crop parts compared to the control sample. The chemical constituents in soil and crop parts showed negligible variation with increasing proportions of gypsum powder. Gypsum loaded Ca, SO4, Mn, and Pb onto the soil, which exhibited higher Mg, Cu, Mo, Cd, NO3, and PO4 but the comparable concentrations of Fe, K, Zn, and Cr in decreasing order. However, a direct relationship was noted in chemical constituent loadings along the pathway:  powder-soil-crop in a similar fashion in the three mixes. Factor analyses revealed that wheat parts have a higher accumulation of nutrients than the barley parts with higher content in its growth soil blends.  As an extension of this research, the in-situ investigation is recommended to assess the direct impact of the gypsum powder emitted over the soil and crops.

Cathodoluminescence of Catalyst Crystallites

1982 ◽  
Vol 40 ◽  
pp. 664-665
Author(s):  
E.D. Boyes ◽  
P.L. Gai ◽  
D.B. Darby ◽  
C. Warwick
Keyword(s):  
Defect Density ◽  
Chemical Properties ◽  
Operating Conditions ◽  
Semiconductor Materials ◽  
Environmental Cell ◽  
High Resolution Structure ◽  
Commercially Important ◽  
Crystallographic Defects ◽  
Resolution Structure

The extended crystallographic defects introduced into some oxide catalysts under operating conditions may be a consequence and accommodation of the changes produced by the catalytic activity, rather than always being the origin of the reactivity. Operation without such defects has been established for the commercially important tellurium molybdate system. in addition it is clear that the point defect density and the electronic structure can both have a significant influence on the chemical properties and hence on the effectiveness (activity and selectivity) of the material as a catalyst. SEM/probe techniques more commonly applied to semiconductor materials, have been investigated to supplement the information obtained from in-situ environmental cell HVEM, ultra-high resolution structure imaging and more conventional AEM and EPMA chemical microanalysis.

In situ investigation of the primary recrystallization of alpha titanium in HVEM

1978 ◽  
Vol 36 (1) ◽  
pp. 634-635
Author(s):  
S. Naka ◽  
R. Penelle ◽  
R. Valle
Keyword(s):  
Dimensional Analysis ◽  
Texture Evolution ◽  
Cold Work ◽  
Three Dimensional ◽  
Primary Recrystallization ◽  
Thin Foils ◽  
In Situ Investigation ◽  
Grain Growth Model ◽  
Alpha Titanium

The in situ experimentation technique in HVEM seems to be particularly suitable to clarify the processes involved in recrystallization. The material under investigation was unidirectionally cold-rolled titanium of commercial purity. The problem was approached in two different ways. The three-dimensional analysis of textures was used to describe the texture evolution during the primary recrystallization. Observations of bulk-annealed specimens or thin foils annealed in the microscope were also made in order to provide information concerning the mechanisms involved in the formation of new grains. In contrast to the already published work on titanium, this investigation takes into consideration different values of the cold-work ratio, the temperature and the annealing time.Two different models are commonly used to explain the recrystallization textures i.e. the selective grain growth model (Beck) or the oriented nucleation model (Burgers). The three-dimensional analysis of both the rolling and recrystallization textures was performed to identify the mechanismsl involved in the recrystallization of titanium.

In-situ Investigation of Bainite Formation with fast X-Ray Diffraction (iXRD)

2017 ◽  
Vol 72 (6) ◽  
pp. 355-364
Author(s):  
A. Kopp ◽  
T. Bernthaler ◽  
D. Schmid ◽  
G. Ketzer-Raichle ◽  
G. Schneider
Keyword(s):  
X Ray Diffraction ◽  
X Ray ◽  
In Situ Investigation

scholarly journals Lithium-mediated Ferration of Fluoroarenes

2020 ◽  
Vol 74 (11) ◽  
pp. 866-870
Author(s):  
Lewis C. H. Maddock ◽  
Alan Kennedy ◽  
Eva Hevia
Keyword(s):  
Hydrogen Atom ◽  
Organometallic Chemistry ◽  
Room Temperature ◽  
Structural Elucidation ◽  
Side Reactions ◽  
Metal Base ◽  
Lithium Amide ◽  
Mixed Metal ◽  
Important Challenge

While fluoroaryl fragments are ubiquitous in many pharmaceuticals, the deprotonation of fluoroarenes using organolithium bases constitutes an important challenge in polar organometallic chemistry. This has been widely attributed to the low stability of the in situ generated aryl lithium intermediates that even at –78 °C can undergo unwanted side reactions. Herein, pairing lithium amide LiHMDS (HMDS = N{SiMe3}2) with FeII(HMDS)2 enables the selective deprotonation at room temperature of pentafluorobenzene and 1,3,5-trifluorobenzene via the mixed-metal base [(dioxane)LiFe(HMDS)3] (1) (dioxane = 1,4-dioxane). Structural elucidation of the organometallic intermediates [(dioxane)Li(HMDS)2Fe(ArF)] (ArF = C6F5, 2; 1,3,5-F3-C6H2, 3) prior electrophilic interception demonstrates that these deprotonations are actually ferrations, with Fe occupying the position previously filled by a hydrogen atom. Notwithstanding, the presence of lithium is essential for the reactions to take place as Fe II (HMDS)2 on its own is completely inert towards the metallation of these substrates. Interestingly 2 and 3 are thermally stable and they do not undergo benzyne formation via LiF elimination.

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