Evaluation of Mechanochemical and Hydrothermal Transformations in a Wet-Milled Alumina by Transmission Electron Microscopy and Thermal Analysis

2016 ◽  
Vol 881 ◽  
pp. 46-51
Author(s):  
Humberto Naoyuki Yoshimura ◽  
Maurício Batista de Lima ◽  
Sydney Ferreira Santos ◽  
Fernando dos Santos Ortega
Keyword(s):  
Electron Microscopy ◽  
Thermal Analysis ◽  
Transmission Electron Microscopy ◽  
Hydrothermal Treatment ◽  
Basic Medium ◽  
Alumina Powder ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Aluminum Hydroxides ◽  
Transmission Electron

Milling and hydrothermal treatment of alumina powders in aqueous medium can result in surface transformations generating aluminum hydroxides. The aim of this work was to advance the understanding on these transformations. A α-alumina powder was ball milled in water at different pHs for 10 h, and then autoclaved (150 °C, 3 atm, 3 h). The powders were analyzed by transmission electron microscopy, differential scanning calorimetry simultaneously with thermogravimetry, X-ray diffraction, and infrared spectroscopy. It was observed that milling in basic medium caused the formation of doyleite [Al (OH3)] nanoparticles, which were fully converted to boehmite (AlOOH) by hydrothermal treatment. The boehmite fraction determined by thermal analysis was 1.7 wt%. The powder milled in acid medium had no mechanochemical and hydrothermal transformations.

Preparation and Property of Al87Ce3Ni8.5Mn1.5 Nanophase Amorphous Composites

2011 ◽  
Vol 412 ◽  
pp. 263-266
Author(s):  
Hong Wei Zhang ◽  
Li Li Zhang ◽  
Feng Rui Zhai ◽  
Jia Jin Tian ◽  
Can Bang Zhang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Single Phase ◽  
Volume Fraction ◽  
Material Structure ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Different Temperatures

The higher mechanical strength of Al87Ce3Ni8.5Mn1.5 nanophase amorphous composites has been obtained with two methods. The first nanophase amorphous composites are directly produced by the single roller spin quenching technology. The method taken for the second nanophase amorphous composites is at first to obtain amorphous single-phase alloy, followed by annealed at different temperatures .The formative condition, the microstructure, the particle size, the volume fraction of α-Al phase and microhardness of nanophase amorphous composites etc have been investigated and compared by X-ray diffraction (XRD) and transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The microstructure of composites produced by the second method is higher than the former, the fabricated material structure of the system is more uniform and the process is easier to control.

Crystallization of Amorphous Si In Al/Si Multilayers

1991 ◽  
Vol 230 ◽  
Author(s):  
Toyohiko J. Konno ◽  
Robert Sinclair
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Differential Scanning Calorimetry ◽  
Layered Structure ◽  
Heat Of Reaction ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Amorphous Si

AbstractThe crystallization of amorphous Si in a Al/Si multilayer (with a modulation length of about 120Å) was investigated using transmission electron microscopy, differential scanning calorimetry and X-ray diffraction. Amorphous Si was found to crystallize at about 175 °C with the heat of reaction of 11±2(kJ/mol). Al grains grow prior to the nucleation of crystalline Si. The crystalline Si was found to nucleate within the grown Al layers. The incipient crystalline Si initially grows within the Al layer and then spreads through the amorphous Si and other Al layers. Because of extensive intermixing, the original layered structure is destroyed. The Al(111) texture is also enhanced.

On the destruction of kaolinite and gibbsite by phenylphosphonic, phenylphosphinic and phenylarsonic acids: evidence for the formation of new Al compounds

Clay Minerals ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 391-404 ◽  
Author(s):  
J. E. F. C. Gardolinski ◽  
G. Lagaly ◽  
M. Czank
Keyword(s):  
Electron Microscopy ◽  
Thermal Analysis ◽  
Transmission Electron Microscopy ◽  
Fourier Transform ◽  
Linear Chain ◽  
X Ray Diffraction ◽  
Phenylphosphonic Acid ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron

AbstractKaolinite and synthetic γ-Al(OH)3 (gibbsite or hydrargillite) were reacted with phenylphosphonic, phenylphosphinic and 2-nitrophenol-4-arsonic acids. The products were studied by powder X-ray diffraction, transmission electron microscopy/selected area electron diffraction/ energy dispersive X-ray/Fourier transform infrared and simultaneous thermogravimetric/differential thermal analysis. The acids were not intercalated but, instead, easily destroyed the structure of the minerals. Lamellar Al phenylphosphonate and aluminium phenylphosphinate and phenylarsonate with polymeric linear-chain structures were formed from kaolinite. The reaction between gibbsite and the same acids yielded almost identical products. No evidence of formation of grafted kaolinite derivatives after the reaction with phenylphosphonic acid was found.

Low-temperature instability of Ti2SnC: A combined transmission electron microscopy, differential scanning calorimetry, and x-ray diffraction investigations

2009 ◽  
Vol 24 (1) ◽  
pp. 39-49 ◽  
Author(s):  
J. Zhang ◽  
B. Liu ◽  
J.Y. Wang ◽  
Y.C. Zhou
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Differential Scanning Calorimetry ◽  
Low Temperature ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Temperature Instability ◽  
X Ray ◽  
Transmission Electron ◽  
Ceramic Microstructure

Transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and x-ray diffraction (XRD) investigations were conducted on the hot-pressed Ti2SnC bulk ceramic. Microstructure features of bulk Ti2SnC ceramic were characterized by using TEM, and a needle-shaped β-Sn precipitation was observed inside Ti2SnC grains with the orientation relationship: (0001) Ti2SnC // (200) Sn and Ti2SnC // [001] Sn. With the combination of DSC and XRD analyses, the precipitation of metallic Sn was demonstrated to be a thermal stress-induced process during the cooling procedure. The reheating temperature, even as low as 400 °C, could trigger the precipitation of Sn from Ti2SnC, which indicated the low-temperature instability of Ti2SnC. A substoichiometry Ti2SnxC formed after depletion of Sn from ternary Ti2SnC phase. Under electron beam irradiation, metallic Sn was observed diffusing back into Ti2SnxC. Furthermore, a new Ti7SnC6 phase with the lattice constants of a = 0.32 and c = 4.1 nm was identified and added in the Ti-Sn-C ternary system.

Room Temperature Synthesis of Cu2O Nanospheres: Optical Properties and Thermal Behavior

2014 ◽  
Vol 21 (1) ◽  
pp. 108-119 ◽  
Author(s):  
Daniela Nunes ◽  
Lídia Santos ◽  
Paulo Duarte ◽  
Ana Pimentel ◽  
Joana V. Pinto ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Thermal Behavior ◽  
Room Temperature ◽  
Diffuse Reflectance Spectroscopy ◽  
Ion Beam ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron

AbstractThe present work reports a simple and easy wet chemistry synthesis of cuprous oxide (Cu2O) nanospheres at room temperature without surfactants and using different precursors. Structural characterization was carried out by X-ray diffraction, transmission electron microscopy, and scanning electron microscopy coupled with focused ion beam and energy-dispersive X-ray spectroscopy. The optical band gaps were determined from diffuse reflectance spectroscopy. The photoluminescence behavior of the as-synthesized nanospheres showed significant differences depending on the precursors used. The Cu2O nanospheres were constituted by aggregates of nanocrystals, in which an on/off emission behavior of each individual nanocrystal was identified during transmission electron microscopy observations. The thermal behavior of the Cu2O nanospheres was investigated with in situ X-ray diffraction and differential scanning calorimetry experiments. Remarkable structural differences were observed for the nanospheres annealed in air, which turned into hollow spherical structures surrounded by outsized nanocrystals.

Interfacial Reaction in Aluminum/Carbon Multilayer Thin Films

1997 ◽  
Vol 481 ◽  
Author(s):  
K. Landry ◽  
H. Sieber ◽  
M. Sui ◽  
J. H. Perepezko
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Second Step ◽  
Multilayer Thin Films ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Modulation Wavelength

ABSTRACTThe reaction at the interface between Al and amorphous C in Al/C multilayer thin films with modulation wavelengths of about 25nm and 125nm has been investigated by differential scanning calorimetry, X-ray diffraction, transmission electron microscopy/selected area electron diffraction and high resolution transmission electron microscopy. The reaction was found to take place in two steps. The first step onsets at about 300°C, and was identified as the diffusion of C into Al. The second step starts above 400°C, at a temperature strongly dependent on the modulation wavelength of the film, and is the formation of A14C3. The carbide has been observed to nucleate and grow inside the Al layers. The multilayer structure is preserved in the samples up to at least 550°C, and Al grains start to grow at or below 300°C.

Facile Removal of Pesticides from Aqueous Solutions Using Magnetic Nanocomposites I. Synthesis and characterization of the adsorbent material

2019 ◽  
Vol 70 (11) ◽  
pp. 3931-3934
Author(s):  
Irina Fierascu ◽  
Raluca Somoghi ◽  
Cristian Andi Nicolae ◽  
Nicolae Stanica ◽  
Radu Claudiu Fierascu
Keyword(s):  
Electron Microscopy ◽  
Thermal Analysis ◽  
Transmission Electron Microscopy ◽  
Aqueous Solutions ◽  
Synthesis And Characterization ◽  
Magnetic Nanocomposites ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

An inorganic/organic magnetic nanocomposite was synthesized and analytically characterized using X-ray fluorescence, X-ray diffraction, transmission electron microscopy and thermal analysis. The evaluation of the magnetic properties revealed that both the magnetite and the magnetite/chitosan nanocomposite are superparamagnetic with a paramagnetic component, having the saturation magnetization values of 48.04 emu/g, and 41.3 emu/g, respectively. The synthesized material is indented for the adsorption of two known commercial-available pesticides (active ingredients deltamethrin and thiamethoxam, respectively) from aqueous solutions.

PREPARATION AND STRUCTURAL STUDY OF MECHANICAL ALLOYED OF Co50Fe20Cu2V8B20

2005 ◽  
Vol 19 (15n17) ◽  
pp. 2775-2779
Author(s):  
X. F. ZHANG ◽  
X. Q. HUANG ◽  
R. W. PENG ◽  
G. Q. WANG ◽  
S. Y. ZHANG
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Amorphous Alloys ◽  
Supercooled Liquid ◽  
Supercooled Liquid Region ◽  
Liquid Region ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron

The amorphous alloys of Co 50 Fe 20 Cu 2 V 8 B 20 are successfully obtained by using the mechanical alloying technique. The sample is analyzed by X-ray diffraction, transmission electron microscopy and differential scanning calorimetry. The DSC result of the powder sample milled for 120 h shows a complete amorphous phase and a wide supercooled liquid region (Tx - Tg ≃ 80 K ).

Preparation and Photocatalytic Performance of One-Dimensional In2O3 Nanofibers, CuO Microfibers and CuO/In2O3 Heterostructured Nanofibers by Electrospinning Process

NANO ◽  
2016 ◽  
Vol 11 (04) ◽  
pp. 1650048 ◽  
Author(s):  
Fei Zhao ◽  
Qifang Lu ◽  
Zhiliang Xiu ◽  
Chaofeng Zhu
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electrospinning Process ◽  
Xenon Lamp ◽  
Halogen Lamp ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
One Dimensional ◽  
Enhanced Absorption ◽  
Transmission Electron

One-dimensional (1D) CuO/In2O3 heterostructured nanofibers with the diameter of about 300 nm were successfully prepared through combining a facile single-capillary electrospinning with sintering process, and investigated by thermogravimetric and differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) techniques, etc. The photocatalytic activities were examined by degrading methylene blue (MB) under 500W xenon lamp, halogen lamp and mercury lamp irradiation, respectively. The heterostructured nanofibers exhibited a higher photocatalytic activity than P25-TiO2 under 500W xenon lamp irradiation due to the enhanced absorption for visible light and the efficient electron–hole separation and transportation. The single CuO microfibers and In2O3 nanofibers were also prepared as the control groups by the same method.

Preparation and Photocatalysis of Nano-Zn/Ce Composite Oxides

2014 ◽  
Vol 67 (4) ◽  
pp. 657 ◽  
Author(s):  
Xiuping Li ◽  
Yuchun Zhai ◽  
Peihua Ma ◽  
Rongxiang Zhao
Keyword(s):  
Electron Microscopy ◽  
Thermal Analysis ◽  
Transmission Electron Microscopy ◽  
Differential Thermal Analysis ◽  
Precipitation Method ◽  
Diffraction Field ◽  
Infrared Spectrometry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

Metal oxide photocatalysts often lead to partial or complete mineralization of organic pollutants. On irradiation with UV-visible light, metal oxides catalyze redox reactions in the presence of air and O2 and water. Using ascorbic acid as a new combustion agent, ZnO was rapidly synthesized. Nano-Zn/CeO2 composites were prepared by a heterogeneous-precipitation method using (NH4)2CO3 as precipitation agent. X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectrometry, ultraviolet spectrophotometry, and differential thermal analysis were used to analyse the microstructures of the synthesized materials. Differential thermal analysis, transmission electron microscopy, and X-ray diffraction analyses indicated that ZnO was coated by CeO2. Herein, a nano-Zn/Ce composite was explored as a catalyst for Rhodamine B photodegradation with a 125-W lamp as the UV radiation source in a batch reactor. The results show the photocatalytic properties of the nano-Zn/Ce composite were superior to ZnO, CeO2, and nano-Ce/Zn composites.

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