scholarly journals Дефектная структура слоев GaAs, имплантированных ионами азота

2018 ◽  
Vol 44 (18) ◽  
pp. 24
Author(s):  
Н.А. Соболев ◽  
А.Е. Калядин ◽  
К.В. Карабешкин ◽  
Р.Н. Кютт ◽  
В.М. Микушкин ◽  
...  
Keyword(s):  
Dose Range ◽  
Gaas Layer ◽  
Extended Defects ◽  
X Ray Diffraction ◽  
Initial State ◽  
X Ray ◽  
Defect Clusters ◽  
Transmission Electron ◽  
Point Defect Clusters ◽  
Microscopy Techniques

AbstractStructural defects formed in epitaxial GaAs layers as a result of 250-keV N^+ ion implantation to doses within 5 × 10^14–5 × 10^16 cm^–2 have been studied by the X-ray diffraction (XRD) and transmission electron microscopy techniques. No amorphization of the ion-implanted layer took place in the entire dose range studied. The implantation to doses of 5 × 10^14 and 5 × 10^15 cm^–2 led to the appearance of an additional peak on XRD curves, which was related to the formation of a stressed GaAs layer with positive deformation arising due to the formation of point-defect clusters. The implantation to a dose of 5 × 10^16 cm^–2 led to the formation of a dense structure of extended defects in the implanted layer, which was accompanied by the relaxation of macrostresses to the initial state.

scholarly journals Control the Morphologies and the Pore Architectures of Mesoporous Silicas through a Dual-Templating Approach

2012 ◽  
Vol 2012 ◽  
pp. 1-8
Author(s):  
Hairui Wang ◽  
Hao Chen ◽  
Zhen Xu ◽  
Sibing Wang ◽  
Baozong Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mesoporous Silica ◽  
Volume Ratio ◽  
Mesoporous Silicas ◽  
Low Molecular Weight ◽  
Silica Nanospheres ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Microscopy Techniques

Mesoporous silica nanospheres were prepared using a chiral cationic low-molecular-weight amphiphile and organic solvents such as toluene, cyclohexane, and tetrachlorocarbon through a dual-templating approach. X-ray diffraction, nitrogen sorption, field emission scanning electron microscopy, and transmission electron microscopy techniques have been used to characterize the mesoporous silicas. The volume ratio of toluene to water plays an important role in controlling the morphologies and the pore architectures of the mesoporous silicas. It was also found that mesoporous silica nanoflakes can be prepared by adding tetrahydrofuran to the reaction mixtures.

Nickel oxide–silica and nickel–silica aerogel and xerogel nanocomposite materials

2000 ◽  
Vol 15 (10) ◽  
pp. 2187-2194 ◽  
Author(s):  
M. F. Casula ◽  
A. Corrias ◽  
G. Paschina
Keyword(s):  
Nickel Oxide ◽  
Sol Gel ◽  
Supercritical Drying ◽  
Nanocomposite Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
The Matrix ◽  
Drying Conditions ◽  
Microscopy Techniques

The sol-gel method was used to prepare nickel oxide–silica and nickel–silica nanocomposite materials and the corresponding silica matrices. Different drying conditions were used to obtain aerogel and xerogel materials. The samples were characterized by thermal analysis, x-ray diffraction, N2–physisorption, transmission electron microscopy techniques, and infrared spectroscopy. Aerogel samples had a much higher surface area than the xerogel samples; moreover, different supercritical drying conditions gave rise to a different porous structure, which influenced the size and distribution of the nanoparticles in the matrix.

Structure and Microstructure Study of Oxides of the La2/3-xLi3xTiO3-family

2008 ◽  
Vol 1126 ◽  
Author(s):  
Ulises Amador ◽  
Susana García-Martín ◽  
Ainhoa Morata-Orrantia ◽  
Juan Rodríguez-Carvajal ◽  
Miguel Ángel Alario-Franco
Keyword(s):  
Extended Defects ◽  
X Ray Diffraction ◽  
Lithium Ions ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Powder Neutron Diffraction ◽  
Transmission Electron ◽  
Square Planar ◽  
Structure And Microstructure ◽  
Very High

AbstractMaterials of the La2/3-xLi3xTiO3–family have been studied by selected area electron diffraction (SAED), high-resolution transmission electron microscopy (HRTEM), powder synchrotron X-ray diffraction and powder neutron diffraction. HRTEM showed that the materials have a complex domain-microstructure. The size and shape of the domains have been obtained from synchrotron X-ray diffraction data; besides, other extended defects such as strains and compositional fluctuations have been detected. The complementary use of local (SAED and HRTEM) and average (SXRD and NPD) techniques have allowed us to propose a model to refine the crystal structure of these oxides also accounting for their microstructure. All these materials have a perovskite-related structure with a diagonal unit cell (≈√2ap x √2ap x 2ap) as a consequence of the tilting of the TiO6 octahedra. Ordering of lanthanum and lithium ions and vacancies along the 2ap-axis, as well as displacements of titanium ions from the centre of the octahedra, have been determined. The Li+ ions present a distorted square planar coordination and are located in interstitial positions of the structure, which could explain the very high ionic conductivity of this type of materials. The lithium conductivity depends on the oxide composition and its crystal microstructure, which varies with the thermal treatment of the sample.

scholarly journals Poirierite, a dense metastable polymorph of magnesium iron silicate in shocked meteorites

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Naotaka Tomioka ◽  
Luca Bindi ◽  
Takuo Okuchi ◽  
Masaaki Miyahara ◽  
Toshiaki Iitaka ◽  
...  
Keyword(s):  
Iron Silicate ◽  
Intermediate Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Naturally Occurring ◽  
Transmission Electron ◽  
Rapid Decompression ◽  
Transitional Forms ◽  
Microscopy Techniques ◽  
Impact Events

AbstractA dense magnesium iron silicate polymorph with a structure intermediate between olivine, ringwoodite, and wadsleyite was theoretically predicted about four decades ago. As this group of minerals constitute the major component of shocked meteorites, constraining their transitional forms and behaviour is of potential importance for understanding impact events on their parent bodies. Here we use high-resolution transmission electron microscopy techniques and single-crystal X-ray diffraction analyses to identify naturally occurring examples of this mineral – recently named poirierite – in shocked chondritic meteorites. We observe nanoscale lamellar poirierite topotactically intergrown within wadsleyite, and additionally within ringwoodite as recently reported. Our results confirm the intermediate structure of poirierite and suggest it might be a relay point in the shear transformations between its polymorphs. We propose that poirierite formed during rapid decompression at relatively low temperature in retrograde shock metamorphism of the meteorites.

X-Ray Analysis of Fatigue Softening in Cold Worked Copper

1968 ◽  
Vol 12 ◽  
pp. 236-248 ◽  
Author(s):  
Roy G. Baggerly ◽  
Regis M. N. Pelloux
Keyword(s):  
Room Temperature ◽  
Small Strain ◽  
Thermal Recovery ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Cold Worked ◽  
And Migration ◽  
Number Of Cycles ◽  
Microscopy Techniques

AbstractThe recovery and recrystallization of cold rolled copper during reverse bending fatigue at room temperature has been studied with x-ray diffraction, optical microscopy and transmission electron microscopy techniques. Recovery of x-ray line breadth was recorded as a function of number of cycles at all strain amplitudes investigated. Recrystallization was observed to take place only at small strain amplitudes (life of 106 to 107 cycles). The rate of nucleation of the recrystallized grains increases with increasing strain amplitude and is a linear function of the number of cycles. The formation and growth of the grains was confined to regions near the surface of the specimen. Since comparable thermal recovery occurs at approximately 435°F it is concluded that the dynamic generation and migration of numerous point defects during fatigue is responsible for the room temperature recrystallization.

Correlation between Extended Defects and Surface Morphology in MBE Grown InAs/GaAs Heterostructures

1995 ◽  
Vol 399 ◽  
Author(s):  
M.R. Bruni ◽  
G. Padeletti ◽  
M.G. Simeone ◽  
L. Francesio ◽  
P. Franzosi ◽  
...  
Keyword(s):  
Surface Morphology ◽  
Growth Temperature ◽  
Crystal Defects ◽  
Extended Defects ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Gaas Substrates ◽  
Transmission Electron

ABSTRACTInAs single layers were grown by Molecular Beam Epitaxy on nominally (001) oriented GaAs substrates at growth temperatures ranging from 350 °C to 500 °C and thicknesses between 1 nm and 6 μm. A systematic study of the influence of growth temperature and thickness on crystal defects and surface morphology is discussed by comparing High Resolution X-Ray Diffraction, Transmission Electron Microscopy and Atomic Force Microscopy investigations.Surface hexagonal shaped holes were observed to develop at the lowest temperatures starting from an heterolayer thickness of 50 nm. Both misfit and threading dislocations were revealed; moreover the correlation between hexagonal shaped surface holes and mixed dislocations, with the component of the Burgers vector (b) along the growth axis larger than the minimum interatomic distance, is discussed. The holes increase in size and decrease in density by increasing the layer thickness. An almost complete surface planarization is observed at a thickness of 6 μm by increasing the growth temperature up to 500 °C.

STUDY OF FORMATION OF DEFECTS/DEFECT CLUSTERS IN NICKEL NANOWIRES

2020 ◽  
Vol 27 (10) ◽  
pp. 1950216
Author(s):  
SHEHLA HONEY ◽  
JAMIL ASIM ◽  
ISHAQ AHMAD ◽  
TINGKAI ZHAO ◽  
MAAZA MALEK ◽  
...  
Keyword(s):  
Simulation Software ◽  
Harsh Environment ◽  
Beam Irradiation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Defect Clusters ◽  
Nickel Nanowires ◽  
Transmission Electron ◽  
Cascade Effect ◽  
Xrd Techniques

In this paper, formation of defects/defect clusters in nickel nanowires (Ni-NWs) due to interaction of a 60 kilo-electron-volt (keV) beam of proton (H[Formula: see text] ions is studied. Ni-NWs are exposed to various fluencies of H[Formula: see text] ions ranging between [Formula: see text] and [Formula: see text][Formula: see text]ions/cm2. The analysis of pristine and H[Formula: see text] ion-irradiated Ni-NWs samples is mainly done using transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. Stopping range of ions in matter (SRIM) simulation software is employed to verify the production of defect clusters in Ni-NWs theoretically. Furthermore, insight of creation of defects in Ni-NWs due to interaction of low energy H[Formula: see text] ions in keV range is made using the theory of collision cascade effect. The study of defect clusters induced in Ni-NWs under H[Formula: see text] ions beam irradiation is essential for application of Ni-NW-based nanodevices in harsh environment containing plenty of H[Formula: see text] ions such as for use in spacecraft equipped for space missions.

scholarly journals Misfit phase (BiSe)1.10NbSe2 as the origin of superconductivity in niobium-doped bismuth selenide

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Machteld E. Kamminga ◽  
Maria Batuk ◽  
Joke Hadermann ◽  
Simon J. Clarke
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Impurity Phase ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Niobium Doped ◽  
Microscopy Techniques ◽  
Superconducting Behaviour

Abstract Topological superconductivity is of great contemporary interest and has been proposed in doped Bi2Se3, in which electron-donating atoms such as Cu, Sr or Nb have been intercalated into the Bi2Se3 structure. For NbxBi2Se3, with Tc ~ 3 K, it is assumed in the literature that Nb is inserted in the van der Waals gap. However, in this work an alternative origin for the superconductivity in Nb-doped Bi2Se3 is established. In contrast to previous reports, it is deduced that Nb intercalation in Bi2Se3 does not take place. Instead, the superconducting behaviour in samples of nominal composition NbxBi2Se3 results from the (BiSe)1.10NbSe2 misfit phase that is present in the sample as an impurity phase for small x (0.01 ≤ x ≤ 0.10) and as a main phase for large x (x = 0.50). The structure of this misfit phase is studied in detail using a combination of X-ray diffraction and transmission electron microscopy techniques.

HfO2-based Thin Films Deposited by RF Magnetron Sputtering

2009 ◽  
Vol 1160 ◽  
Author(s):  
Larysa Khomenkova ◽  
Christian Dufour ◽  
Pierre-Eugène Coulon ◽  
Caroline Bonafos ◽  
Fabrice Gourbilleau
Keyword(s):  
Magnetron Sputtering ◽  
Annealing Treatment ◽  
Rf Magnetron Sputtering ◽  
X Ray Diffraction ◽  
Post Deposition Annealing ◽  
X Ray ◽  
Deposition Parameters ◽  
Transmission Electron ◽  
Microscopy Techniques ◽  
Post Deposition

AbstractHfO2-based layers prepared by RF magnetron sputtering were studied by X-ray diffraction, infrared absorption spectroscopy and transmission electron microscopy techniques. The effect of the deposition parameters and post-deposition annealing treatment on the properties of the layers was investigated. The amorphous-crystalline transformation of pure HfO2 layers is observed to be stimulated by annealing treatment at 800 ° C. It was found that the incorporation of silicon in HfO2 matrix allows to prevent crystallization of the layers and to shift the crystallization temperature to values up to 900 °C.

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