Micro/nanostructure observation of microwave-heated Fe3O4

2009 ◽  
Vol 24 (5) ◽  
pp. 1741-1747 ◽  
Author(s):  
Noboru Yoshikawa ◽  
Ziping Cao ◽  
Dmitri Louzguin ◽  
Guoqiang Xie ◽  
Shoji Taniguchi
Keyword(s):  
Amorphous Phase ◽  
Single Mode ◽  
Lattice Parameter ◽  
State University ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Penn State ◽  
Local Transport ◽  
O Phase ◽  
Amorphous Phase Formation

To investigate the microwave (MW) processing of Fe3O4, for which occurrence of decrystallization has been reported, the micro/nanostructures of MW-heated Fe3O4 powder were observed in this study. The specimens were irradiated by 2.45 GHz MW at the position of magnetic (H)-field maximum in a TE10 single mode applicator. The specimen was heated well above the Curie temperature in H-field. The heated specimen above 1000 °C revealed the glass-like surface with the diminished x-ray diffraction (XRD) peak intensities. They resemble the reported features of decrystallization in an earlier work performed at Penn State University. According to the XRD profiles of the MW-heated specimens, formation of FeO and shift of Fe3O4 peaks to the lower angle with the broadened width were observed. To account for the findings, a model is presented that phase separation occurred into FeO and Fe3O4 resulting in an increased lattice parameter due to the increased oxygen content. This activity is caused by local transport of oxygen in nanoscale. Considering the shape of the main XRD Fe3O4 peak with a shoulder and the existence of halo in nanobeam diffraction (NBD), amorphous phase areas exist. As a result of transmission electron microscopy observation, it was shown that they were in nanoscaled localized regions, and it was not confirmed that the glass-like morphologies (or decrystallized morphologies) are totally amorphous. The observed micro/nanostructures and mechanism of the amorphous phase formation were discussed considering the Fe-O phase diagram.

Effects of Milling Variables in Amorphous Phase Formation of Fe78Si9B13 Alloy Produced by Mechanical Alloying

2021 ◽  
Vol 876 ◽  
pp. 19-24
Author(s):  
Raquel Astacio López ◽  
Rosa M. Aranda Louvier ◽  
Petr Urban ◽  
Fátima Ternero Fernández ◽  
Juan Manuel Montes Martos
Keyword(s):  
Electron Microscopy ◽  
Mechanical Alloying ◽  
Amorphous Phase ◽  
Milling Time ◽  
Morphological Evolution ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Nanocrystalline And Amorphous ◽  
Gas Atmosphere ◽  
Amorphous Phase Formation

In this study, amorphous Fe78Si9B13 alloy was successfully synthesized by mechanical alloying (MA) of pure elemental powders which were milled under an argon gas atmosphere. Effects of milling time on the phase transformation, microstructure and morphological evolution were studied by X-ray diffraction (XRD), laser diffraction (Granulometry), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results showed that by increasing the milling time, the nanocrystalline and amorphous phase content increases and alloys with good properties are obtained at 100 h of milling.

Hydrogenation Properties of Mg-Co and Its Related Alloys

2005 ◽  
Vol 475-479 ◽  
pp. 2453-2456
Author(s):  
Y. Zhang ◽  
Y. Tsushio ◽  
Hirotoshi Enoki ◽  
Etsuo Akiba
Keyword(s):  
Binary Alloys ◽  
Lattice Parameter ◽  
Ternary Alloys ◽  
Body Centered Cubic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Co Concentration ◽  
Bcc Structure ◽  
Co Alloys

Novel Mg-Co binary alloys with BCC (body-centered cubic) structure have been successfully synthesized by means of mechanical alloying technique. The formation of BCC structure was confirmed by X-ray diffraction and transmission electron microscopy. Mg-Co alloys were found in the range of Co concentration between 37 and 80 atomic %. All the Mg-Co alloys synthesized absorbed hydrogen below 373K. The maximum hydrogen capacity of these alloys reaches 2.7 mass %. However, desorption of hydrogen at 373 K has not been observed yet. Mg- Co-X (X = B and Ni) ternary alloys with BCC structure have also been synthesized. The lattice parameter of both alloys is lower than that of Mg-Co binary alloys, meanwhile the maximum hydrogen content of both alloys also decreased.

Epitaxial Growth and Structure of Cubic and Pseudocubic Perovskite Films on Perovskite Substrates

1995 ◽  
Vol 401 ◽  
Author(s):  
P. A. Langjahr ◽  
T. Wagner ◽  
M. RÜhle ◽  
F. F. Lange
Keyword(s):  
Electron Microscopy ◽  
Epitaxial Growth ◽  
Lattice Mismatch ◽  
High Resolution Electron Microscopy ◽  
Lattice Parameter ◽  
Ternary Oxide ◽  
Misfit Dislocations ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Resolution Electron

AbstractCubic and pseudocubic perovskite films on perovskite substrates are used to study the influence of the lattice mismatch on the epitaxial growth of thin films on substrates of the same structure. For the growth of the films, a metalorganic decomposition route (MOD) using 2-ethylhexanoates and neodecanoates as precursors, was developed. The decomposition of the precursors was investigated with thermogravimetric analysis (TGA) and x-ray diffraction (XRD). The films were spin-coated on (001)-oriented SrTiO3- and LaAlO3-substrates, pyrolyzed and afterwards annealed between 600°C and 1200°C. XRD-nvestigations and conventional transmission electron microscopy (CTEM) show, that epitaxial films with the orientation relationship [100](001) film ║ [100](001) substrate can be grown. With XRD, it could be shown, that not only ternary oxide films (SrZrO3, BaZrO3 and BaCeO3), but also perovskite solid solution films (SrTi0.5Zr0.5O3and BaCe0.5Zr0.5O3) can be prepared. Strong interdiffusion, detected by a shift of the film lattice parameter towards the substrate lattice parameter was found in SrZrO3- and BaZrO3-films on SrTiO3, annealed at temperatures above 1050°C. High resolution electron microscopy (HREM) studies of SrZrO3 on SrTiO3 show that a crystalline semicoherent interface with a periodical array of misfit dislocations is present.

Solid State Amorphization of Ti60Si40 Alloy via Mechanical Alloying

2021 ◽  
Vol 876 ◽  
pp. 7-12
Author(s):  
Petr Urban ◽  
Fátima Ternero Fernández ◽  
Rosa M. Aranda Louvier ◽  
Raquel Astacio López ◽  
Jesus Cintas Físico
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Mechanical Alloying ◽  
Amorphous Phase ◽  
Milling Time ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Heating Up

The effect of milling time on the microstructure evolution and formation of amorphous phase of Ti60Si40 alloy produced by mechanical alloying (MA) has been investigated. Laser diffraction, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Differential Scanning Calorimetry (DSC) were employed to characterize the particle size, morphology and structure of mechanically alloyed Ti60Si40. When the milling time is increased to 20 h, the particle size decreases from 23.7 to 4.7 μm, the shape of the particles changes to spherical and the crystalline structure is transformed into an amorphous phase. The amorphous Ti60Si40 alloy is stable when heating up to 750oC. Above this temperature, the cold crystallization of the intermetallic compounds Ti5Si3 and/or Ti5Si4 begins.

Phase Formation, Stability and Superconducting Properties of Mechanically Alloyed Yttrium-Nickel-Borocarbides

1998 ◽  
Vol 547 ◽  
Author(s):  
L. Ledig ◽  
D. Hough ◽  
C.-G. Oertel ◽  
J. Eckert ◽  
W. Skrotzki
Keyword(s):  
Amorphous Phase ◽  
Amorphous State ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
X Ray ◽  
Milling Parameters ◽  
Transmission Electron ◽  
Nanocrystalline And Amorphous ◽  
Nickel Borocarbides

AbstractThe solid state reaction of YNi2B2C by mechanical alloying of elemental powders has been investigated by X-ray diffraction, transmission electron microscopy and susceptibility measurements. Depending on the ball milling parameters either nanocrystalline YNi2B2C or an amorphous phase can be produced. Crystallization of the amorphous phase by annealing at 893 K produces YNi2B2C as major and Ni2B as minor intermetallic compound. Superconductivity is only observed in the annealed state. However, the transition temperature is much lower than in arc-melted samples. This is discussed with respect to the nanocrystalline and amorphous state as well as deviations from stoichiometry produced by impurities introduced during milling.

Synthesis of Amorphous Ti50Al50 by Mechanical Alloying

2012 ◽  
Vol 531-532 ◽  
pp. 490-495
Author(s):  
Jun Hong Zhang ◽  
Guo Hui Xu ◽  
Ya Juan Xu ◽  
Yue Hui He
Keyword(s):  
Electron Microscope ◽  
Amorphous Phase ◽  
Critical Density ◽  
Host Lattice ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
X Ray ◽  
Blended Elemental ◽  
Transmission Electron ◽  
Size Condition

Blended elemental powders with the nominal compositions (at%) of Ti50Al50, was mechanically alloyed in a planetary ball milling system for up to 100h, an amorphous Ti50Al50 phase was obtained in the process. The amorphization process as a function of time of milling was monitored by scanning electron microscope, X-ray diffraction and transmission electron microscope. It is shown that, as first, Al atoms diffuse into the host lattice of hexagonal Ti; subsequently, the milling accumulates a critical density of disorder that causes the Ti (Al) crystalline phase to collapse into an amorphous phase, it is suggested the grain size condition for formation of amorphous phase is 12nm. On the basis of thermodynamic models, the formation of the amorphous phase is discussed.

Damage and Lattice Strain in Ion-Irradiated AlxGai-xAs

1994 ◽  
Vol 354 ◽  
Author(s):  
P. Partyka ◽  
R.S. Averback ◽  
D.V. Forbes ◽  
J.J. Coleman ◽  
P. Ehrhart ◽  
...  
Keyword(s):  
Rutherford Backscattering Spectrometry ◽  
Lattice Parameter ◽  
Large Strains ◽  
X Ray Diffraction ◽  
Al Content ◽  
Plane Lattice ◽  
Transmission Electron ◽  
Out Of Plane ◽  
Radiation Induced ◽  
High Al Content

AbstractRadiation-induced damage and strain in AlxGai-xAs (x=5 to 1) were investigated by measurements of the lattice parameter using x-ray diffraction. Irradiations employed MeV C, Ar and Au ion beams with a substrate temperature of 80 K. For samples with high Al content, the out-of-plane lattice parameter increased with fluence at low doses, saturated, and then decreased to nearly its original value. The in-plane lattice parameter did not change, throughout. These results were independent of the irradiation particle when scaled by damage energy. For the Al.5Ga.5As samples, however, the out-of-plane lattice parameter increased monotonically with dose to large strains until the layer amorpnized. Selected samples were examined by high resolution and conventional transmission electron microscopy (TEM). Channeling Rutherford backscattering spectrometry (CRBS) was also employed to monitor the buildup of damage in many samples. Recovery of the lattice parameter during subsequent thermal annealing was also investigated.

The Investigation of Structural and Magnetic Properties at High-Temperature of Nanostructured Fe90-Mg10 Alloys Produced by Mechanical Alloying

2018 ◽  
Vol 54 ◽  
pp. 136-145
Author(s):  
A. El Mohri ◽  
M. Zergoug ◽  
K. Taibi ◽  
M. Azzaz
Keyword(s):  
High Temperature ◽  
Mechanical Alloying ◽  
Milling Time ◽  
High Energy ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
High Energy Ball Mill ◽  
Energy Ball ◽  
The Mean

Nanocrystalline Fe90Mg10 alloy samples were prepared by mechanical alloying process using planetary high energy ball mill. The prepared powders were characterized using differential thermal analysis (DTA), X-ray diffraction technique (XRD) at high temperature, transmission electron microscopy (TEM), and the vibrating sample magnetometer (VSM). Obtained results are discussed according to milling time. XRD at high temperature results also indicated that when the milling time increases, the lattice parameter and the mean level of grain size increase, whereas the microstrains decrease. The result of the observation by the TEM of the Fe-Mg powders prepared in different milling time, coercive fields derived and Saturation magnetization derived from the hysteresis curves in high temperature are discussed as a function of milling time.

Morphological and structural evolutions of nonequilibrium titanium-nitride alloy powders produced by reactive ball milling

1992 ◽  
Vol 7 (4) ◽  
pp. 888-893 ◽  
Author(s):  
M. Sherif El-Eskandarany ◽  
K. Sumiyama ◽  
K. Aoki ◽  
K. Suzuki
Keyword(s):  
Electron Microscopy ◽  
Titanium Nitride ◽  
Gas Flow ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Nitrogen Gas ◽  
X Ray ◽  
Grain Sizes ◽  
Transmission Electron

Nonequilibrium titanium-nitride alloy powders have been fabricated by a high energetic ball mill under nitrogen gas flow at room temperature and characterized by means of x-ray diffraction, scanning electron microscopy, transmission electron microscopy, and differential scanning calorimetry. Initial hcp titanium is completely transformed to nonequilibrium-fcc Ti–N after 720 ks of the milling time. The fcc Ti–N phase is stable at relatively low temperature and transforms at 855 K to Ti2N and δ phases. At the final stage of milling, the particle- and grain-sizes of alloy powders are 1 mm and 5 nm, respectively, and the lattice parameter is 0.419 nm.

The Nucleation and Propagation of Misfit Dislocations aear the Critical Thickness in Ge-Si Strained Epilayers

1987 ◽  
Vol 104 ◽  
Author(s):  
E. P. Kvam ◽  
D. J. Eaglesham ◽  
D. M. Maher ◽  
C. J. Humphreys ◽  
J. C. Bean ◽  
...  
Keyword(s):  
Lattice Parameter ◽  
Dislocation Segment ◽  
Misfit Dislocations ◽  
X Ray Diffraction ◽  
Parameter Mismatch ◽  
Growth Interface ◽  
Edge Type ◽  
X Ray ◽  
Transmission Electron ◽  
Dislocation Behavior

ABSTRACTThe nucleation and propagation of misfit dislocations in Ge-Si strained epilayers on (100) Si have been investigated using transmission electron microscopy and X-ray diffraction topography at low lattice parameter mismatch (˜ 0.8%). Misfit dislocations nucleate as half loops which are predominantly unfaulted (> 90%) at the advancing growth interface. Under the driving force of the epilayer strain, unfaulted half loops glide and expand on inclined { 111 }planes toward the heterointerface (i.e. substrate/epilayer interface). These unfaulted half loops consist of a 60°-dislocation segment which lies along < 011> in a plane parallel to the heterointerface (i.e. (100)) and this segment is connected to the growth interface by two screw dislocation segments which both lie on the same inclined {111} glide plane. As 60° dislocations reach the heterointerface on each of the four inclined {111} variants, they form an orthogonal array of misfit dislocations which lie along [011] and [011]. At higher lattice parameter mismatch (˜ 2%), there appear to be some important changes in the dislocation behavior and these changes result in orthogonal arrays of heterointerface dislocations which are predominantly edge type (i.e. 90°dislocations).

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