scholarly journals MECHANISM OF THERMAL DECOMPOSITION OF AMMONIUM METAVANADATE

1964 ◽  
Vol 42 (11) ◽  
pp. 2467-2473 ◽  
Author(s):  
M. Taniguchi ◽  
T. R. Ingraham
Keyword(s):  
Thermal Decomposition ◽  
Intermediate Compound ◽  
Gaseous Product ◽  
Ammonium Metavanadate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Second Stage ◽  
Mechanism Of Thermal Decomposition ◽  
Exothermic Process ◽  
Last Stage

When ammonium metavanadate is roasted at 225 °C, ammonia and water are eliminated in the ratio 2:1 and an intermediate compound identified by weight loss and chemical analysis as (NH4)2•O•V2O5• is formed. An X-ray diffraction pattern for this material is reported. Transpiration experiments have been used to establish the free energy of this reaction. The second stage of the decomposition involves an endothermic and an exothermic process, both of which occur with the production of a gaseous product. The liberation of ammonia is not quantitative, and its oxidation on the vanadium pentoxide, in the last stage of decomposition, is suggested as a possible source of the exothermic heat.

Thermal Decomposition of Ammonium Metavanadate

1975 ◽  
Vol 53 (19) ◽  
pp. 2917-2921 ◽  
Author(s):  
K. C. Khulbe ◽  
R. S. Mann
Keyword(s):  
Thermal Decomposition ◽  
Electron Spin Resonance ◽  
Electron Spin ◽  
Intermediate Compound ◽  
Ammonium Metavanadate ◽  
X Ray ◽  
Spin Resonance ◽  
Infrared Studies

X-Ray, infrared, and electron spin resonance (e.s.r.) studies were made on the samples prepared by the thermal decomposition of ammonium metavanadate at various temperatures between 100 and 700 °C. A new intermediate compound has been identified to be formed between 100 and 150 °C. This new compound is stable up to 200 °C, and is a complex ammonium–vanadyl compound, since while the infrared studies showed the presence of an NH4 group, and V—N bond, the e.s.r. gave the signal of VO2+ ions (V4+ + O2− = VO2+). A mechanism of the decomposition of ammonium metavanadate has been given.

Influence of Alloying Additions on Enhancement of Soft Magnetic Properties Effect and Crystallization in FeXSiB (X=Cu, V, Co, Zr, Nb) Amorphous Alloys

2007 ◽  
Vol 130 ◽  
pp. 171-174 ◽  
Author(s):  
Z. Stokłosa ◽  
G. Badura ◽  
P. Kwapuliński ◽  
Józef Rasek ◽  
G. Haneczok ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Amorphous Alloys ◽  
Crystallization Process ◽  
Annealing Temperature ◽  
Magnetic Measurements ◽  
X Ray Diffraction ◽  
Soft Magnetic ◽  
X Ray ◽  
Second Stage ◽  
Transmission Electron

The crystallization and optimization of magnetic properties effects in FeXSiB (X=Cu, V, Co, Zr, Nb) amorphous alloys were studied by applying X-ray diffraction methods, high resolution transmission electron microscopy (HRTEM), resistometric and magnetic measurements. The temperatures of the first and the second stage of crystallization, the 1h optimization annealing temperature and the Curie temperature were determined for different amorphous alloys. Activation energies of crystallization process were obtained by applying the Kissinger method. The influence of alloy additions on optimization effect and crystallization processes was carefully examined.

scholarly journals A Facile Method to Construct MXene/CuO Nanocomposite with Enhanced Catalytic Activity of CuO on Thermal Decomposition of Ammonium Perchlorate

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2457 ◽  
Author(s):  
Haifeng Zhao ◽  
Jing Lv ◽  
Junshan Sang ◽  
Li Zhu ◽  
Peng Zheng ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Catalytic Activity ◽  
Ammonium Perchlorate ◽  
Photoelectron Spectra ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Improved Performance ◽  
Calcination Method

In this work, a mixing-calcination method was developed to facilely construct MXene/CuO nanocomposite. CuO and MXene were first dispersed in ethanol with sufficient mixing. After solvent evaporation, the dried mixture was calcinated under argon to produce a MXene/CuO nanocomposite. As characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and X-ray photoelectron spectra (XPS), CuO nanoparticles (60–100 nm) were uniformly distributed on the surface and edge of MXene nanosheets. Furthermore, as evaluated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA), the high-temperature decomposition (HTD) temperature decrease of ammonium perchlorate (AP) upon addition of 1 wt% CuO (hybridized with 1 wt% MXene) was comparable with that of 2 wt% CuO alone, suggesting an enhanced catalytic activity of CuO on thermal decomposition of AP upon hybridization with MXene nanosheets. This strategy could be further applied to construct other MXene/transition metal oxide (MXene/TMO) composites with improved performance for various applications.

Influence of Aging Time on the Structural Changes of Cassava Thermoplastic Starch

2012 ◽  
Vol 1372 ◽  
Author(s):  
José H. Mina ◽  
Alex Valadez ◽  
Pedro J. Herrera-Franco ◽  
Tanit Toledano
Keyword(s):  
Yield Stress ◽  
Amorphous Phase ◽  
Structural Changes ◽  
Thermoplastic Starch ◽  
X Ray Diffraction ◽  
X Ray ◽  
Second Stage ◽  
Diffraction Patterns ◽  
Type V ◽  
Stress Drops

ABSTRACTIn this work the change in the structural properties of cassava (manihot sculenta Crantz) thermoplastic starch (TPS) under controlled environment (humidity and temperature) was studied. Fourier Transform Infrared spectroscopy (FTIR) and X-ray diffraction (XRD) results showed an evident increasing in the amorphous phase of the TPS regarding the native starch. There was a relative decrease of the band at 1047 cm-1 associated to crystalline structure of starch compared to the amorphous peak at 1022 cm-1. The X-ray diffraction patterns confirmed the increment of the amorphous phase in the TPS samples. Likewise the X-ray diffraction patterns shows evidence of residual type C crystallinity and the formation of a new crystalline phase type VH due to the orientation induced in plasticization process. In first stage of conditioning the tensile yield stress drops from 7.5 drops to 0.5 MPa and the break strain increases 1000%. At the same time it seems that the crystallinity of the samples increases as was evidenced by the gradually increasing of the FTIR band at 1047 cm-1. In a second stage, the yield stress increases, the break strain drops and the crystallinity continue growing steadily. These findings suggest that coexist two phenomena simultaneously in the samples. A phenomenon of re-crystallization (retrogradation) that tends to make the material more stiff and a process of plasticization that tends to softening it. It seems that the latter mechanism predominates in the first stage, at short times, and the former in the second stage, at older times.

Beobachtungen von Stapelfehlordnungen bei der Oxydation der zweiten zur ersten Stufe des Graphithydrogensulfats / Observation of stacking disorder during the oxidation of second stage to first stage graphite hydrogensulfate

1984 ◽  
Vol 39 (8) ◽  
pp. 768-777 ◽  
Author(s):  
Ko Young Shin ◽  
Hanns-Peter Boehm
Keyword(s):  
Interlayer Spacing ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Order ◽  
Second Stage ◽  
Intermediate Phases ◽  
Degree Of Oxidation ◽  
Stage 1 ◽  
Kinetics Of ◽  
Stacking Disorder

Graphite has been oxidized to graphite hydrogensulfate with (NH4)2S2Og in concentrated H2SO4. The stage 2 compound formed very rapidly, but further oxidation to stage 1 could be followed conveniently. X-ray diffraction of the intermediate phases showed nonintegral (00l)-reflections indicative of partial interstratification disorder. The interlayer spacing of the stage 1 compound increased with continued oxidation. The degree of oxidation as function of oxidation time has been determined from the position of the minima in the reflectance spectra. The density of the compounds and the ratio of acid molecules to anions in the intercalated layers has been estimated using these data and those of buoyancy measurements. There is a minimum in packing density early in the formation of the first stage. The kinetics of intercalation seems to be first order with respect to the free interlayer spaces.

Structural Characterization and Thermal Decomposition of Lime Binders Allow Accurate Radiocarbon Age Determinations of Aerial Lime Plaster

Radiocarbon ◽  
2020 ◽  
Vol 62 (3) ◽  
pp. 633-655 ◽  
Author(s):  
Michael B Toffolo ◽  
Lior Regev ◽  
Eugenia Mintz ◽  
Ifat Kaplan-Ashiri ◽  
Francesco Berna ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Isotopic Signature ◽  
Secondary Phases ◽  
X Ray Diffraction ◽  
Lime Mortar ◽  
X Ray ◽  
Radiocarbon Age ◽  
Carbon Recovery ◽  
Lime Plaster ◽  
Thin Section Petrography

ABSTRACTRadiocarbon (14C) dating of anthropogenic carbonates (CaCO3) such as ash, lime plaster and lime mortar, has proven a difficult task due to the occurrence of a number of contaminants embedded within the CaCO3 pyrogenic binder. These include 14C-free geologic components and/or secondary phases bearing an unknown amount of 14C, and thus the alteration of the original pyrogenic isotopic signature of the material results in major age offsets when carbon recovery is performed through acid hydrolysis. Here we present a characterization/quantification approach to anthropogenic carbonates that includes Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, thin section petrography, thermogravimetric analysis and scanning electron microscopy coupled with high-resolution cathodoluminescence, with which we identified the pyrogenic CaCO3 fraction in an aerial lime plaster and two hydraulic mortars. The preserved pyrogenic component was then isolated by density separation and its purity checked again using FTIR. Carbon was recovered through thermal decomposition in vacuum. The resulting 14C age matches the expected age of the lime plaster, whereas hydraulic mortars are slightly offset due to the carbonation of calcium hydroxide lumps. This approach highlights the importance of a dedicated characterization strategy prior to dating and may be applied to aerial lime plasters to obtain accurate ages.

scholarly journals Preparation and Properties of Nanocellulose from Miscanthus x giganteus

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Valerii A. Barbash ◽  
Olha V. Yashchenko ◽  
Olesia A. Vasylieva
Keyword(s):  
Structural Changes ◽  
Thermochemical Treatment ◽  
Crystallinity Index ◽  
Alkaline Treatment ◽  
X Ray Diffraction ◽  
Miscanthus X Giganteus ◽  
X Ray ◽  
Second Stage ◽  
20 Nm ◽  
Hydrolysis Of

Miscanthus x giganteus stalks were used to make organosolvent pulp and nanocellulose. The organosolvent miscanthus pulp (OMP) was obtained through thermal treatment in the mixture of glacial acetic acid and hydrogen peroxide at the first stage and the alkaline treatment at the second stage. Hydrolysis of the never-dried OМP was carried out by a solution of sulfuric acid with concentrations of 43% and 50% and followed by ultrasound treatment. Structural changes and the crystallinity index of OMP and nanocellulose were studied by SEM and FTIR methods. X-ray diffraction analysis confirmed an increase in the crystallinity of OMP and nanocellulose as a result of thermochemical treatment. We show that nanocellulose has a density of up to 1.6 g/cm3, transparency up to 82%, and a crystallinity index of 76.5%. The AFM method showed that the particles of nanocellulose have a diameter in the range from 10 to 20 nm. A thermogravimetric analysis confirmed that nanocellulose films have a denser structure and lower mass loss in the temperature range of 320–440°C compared to OMP. The obtained nanocellulose films have high tensile strength up to 195 MPa. The nanocellulose obtained from OMP exhibits the improved properties for the preparation of new nanocomposite materials.

Accelerated Thermal Decomposition of Graphene Oxide Films in Air via in Situ X-ray Diffraction Analysis

2016 ◽  
Vol 120 (27) ◽  
pp. 14984-14990 ◽  
Author(s):  
Qin Pan ◽  
Ching-Chang Chung ◽  
Nanfei He ◽  
Jacob L. Jones ◽  
Wei Gao
Keyword(s):  
Thermal Decomposition ◽  
Graphene Oxide ◽  
Diffraction Analysis ◽  
Oxide Films ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals Fabrication of Large-Grain Thick Polycrystalline Silicon Thin Films via Aluminum-Induced Crystallization for Application in Solar Cells

2013 ◽  
Vol 2013 ◽  
pp. 1-4
Author(s):  
Hsiao-Yeh Chu ◽  
Min-Hang Weng ◽  
Chen Lin
Keyword(s):  
Solar Cells ◽  
Polycrystalline Silicon ◽  
X Ray Diffraction ◽  
X Ray ◽  
Second Stage ◽  
Silicon Thin Films ◽  
Si Films ◽  
Two Stages ◽  
Induced Crystallization ◽  
Aluminum Induced Crystallization

The fabrication of large-grain 1.25 μm thick polycrystalline silicon (poly-Si) films via two-stage aluminum-induced crystallization (AIC) for application in thin-film solar cells is reported. The induced 250 nm thick poly-Si film in the first stage is used as the seed layer for the crystallization of a 1 μm thick amorphous silicon (a-Si) film in the second stage. The annealing temperatures in the two stages are both 500°C. The effect of annealing time (15, 30, 60, and 120 minutes) in the second stage on the crystallization of a-Si film is investigated using X-ray diffraction (XRD), scanning electron microscopy, and Raman spectroscopy. XRD and Raman results confirm that the induced poly-Si films are induced by the proposed process.

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