Characteristic features of theFe7Mo6-type structure in a transition-metal alloy examined using transmission electron microscopy

2006 ◽  
Vol 74 (5) ◽  
Author(s):  
Akihiko Hirata ◽  
Ayumi Iwai ◽  
Yasumasa Koyama
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Transition Metal ◽  
Metal Alloy ◽  
Type Structure ◽  
Transition Metal Alloy ◽  
Transmission Electron ◽  
Characteristic Features

Ultrastructural and cytological observations of apothecial tissues of Geopyxis carbonaria (Pezizales, Ascomycetes)

1990 ◽  
Vol 68 (2) ◽  
pp. 243-257 ◽  
Author(s):  
James W. Kimbrough ◽  
Jack L. Gibson
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Key Words ◽  
Mother Cell ◽  
Secondary Wall ◽  
Cell Stage ◽  
Wall Structures ◽  
Transmission Electron ◽  
Secondary Wall Formation ◽  
Characteristic Features

Cytological observations are made on apothecial tissues of Geopyxis carbonaria, using transmission electron microscopy. Characteristic features of both the medullary and ectal excipula are examined. Changes in ascus apex and wall structures are examined during ascus ontogeny, especially in relation to operculum position and structure. Ultrastructure of septum configuration is observed and compared in the excipulum, ascogenous hyphae, paraphyses, and at the base of young asci. Ascosporogenesis is observed from the ascus mother cell stage and initial spore delimitation until secondary wall formation. The cytological and ultrastructural observations on this species are discussed in relation to their possible taxonomic or phylogenetic value. Key words: ascosporogenesis, Discomycetes, ascospore ultrastructure, septal ultrastructure, cytochemistry.

Valence Mapping of Particulate 3D-Transition Metal Oxides Using Energyfiltered Transmission Electron Microscopy

2000 ◽  
Vol 6 (S2) ◽  
pp. 176-177
Author(s):  
R.M. Stroud ◽  
J.H. Scott
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Data Extraction ◽  
Mixed Valence ◽  
Charge Localization ◽  
Transmission Electron ◽  
Critical Issues

Particulate, mixed-valence transition metal oxides are frequently used for battery, catalytic and magnetic applications. For example, the Li ion exchange battery exploits charge transfer of mixed Mn+3, Mn+4 materials. Charge localization and phase separation, especially at particle surfaces, are critical issues for determining the materials’ useful properties, be it catalytic activity or saturation magnetization. The ability to image the charge localization and correlate this with crystallographic information would be extremely useful in the study of this class of materials. Using energy-filtered transmission electron microscopy (EFTEM), valence maps of Mn and Co with a ∼ 2 nm scale have been obtained for bulk samples. In principal this technique can de directly extended to the case of particulate samples, however there are some additional experimental challenges, such as thickness and edge effects, that must be addressed. We demonstrate here the feasibility of valence mapping of particulate samples, and discuss the factors that limit quantitative data extraction from the maps.

Morphology of Precipitates in Ni-Al-Cr Intermetallic Alloy

2007 ◽  
Vol 130 ◽  
pp. 159-162
Author(s):  
Mirosław Pilawa ◽  
Elżbieta Jezierska
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Intermetallic Alloy ◽  
Nickel Base Superalloy ◽  
Transmission Electron ◽  
Characteristic Features ◽  
Secondary Precipitates ◽  
Nickel Base ◽  
Base Superalloy

Transmission electron microscopy was used to study various morphologies of ordered precipitates in Ni3Al-Cr intermetallic alloy. It was found that γ’ precipitates in the interdendritic regions have the microstructure of a nickel base superalloy with its characteristic features. In addition to the primary γ’ precipitates some fine secondary precipitates were found.

Characteristic Features of the Modulated Structure Appearing in the Multiferroic Material Bi1-xSmxFeO3 around x = 0.15

2016 ◽  
Vol 879 ◽  
pp. 1393-1398 ◽  
Author(s):  
Masashi Nomoto ◽  
Takumi Inoshita ◽  
Yasuhide Inoue ◽  
Yoichi Horibe ◽  
Yasumasa Koyama
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Transverse Waves ◽  
Modulated Structure ◽  
Transmission Electron ◽  
Multiferroic Bifeo ◽  
State Boundary ◽  
Characteristic Features ◽  
Coexistence State ◽  
Transverse Modulation

In Bi1-xSmxFeO3 (BSFO) having the multiferroic BiFeO3 as an end material, when the Sm content increases from x = 0, it has been reported that the ferroelectric-R3c state is changed into the paraelectric-Pnma state around x = 0.14. The R3c/Pnma state boundary around x = 0.14 can be regarded as a temperature-independent morphotropic-phase boundary (MPB). The notable feature in BSFO is that, in addition to these two states, the antiferroelectric PbZrO3-type state was also found in the vicinity of the MPB. Although the PbZrO3-type state appears as a modulated structure, its detailed features have not been understood yet. We have thus examined the crystallographic features of prepared BSFO samples around x = 0.14, mainly by transmission electron microscopy. The PbZrO3-type state was confirmed to be present in samples with x = 0.15 on the basis of x-ray powder diffraction profiles measured from prepared samples at 300 K. On the other hand, the observation made by transmission electron microscopy indicated that the state for x = 0.15 is characterized by a coexistence state consisting of the ferroelectric-R3c and antiferroelectric PbZrO3-type states. In particular, the crystal structure of the PbZrO3-type state could be identified as a modulated structure with two transverse modulation waves, whose wave vectors are given by q1 = [1/2 0 0]o and q2 = [0 1/2 0]o in the orthorhombic-Pnma notation. In addition, eigenvectors of these two transverse waves were also determined to be parallel to the same [001]o direction.

scholarly journals Atomic structure of defects and dopants in 2D layered transition metal dichalcogenides

2018 ◽  
Vol 47 (17) ◽  
pp. 6764-6794 ◽  
Author(s):  
Shanshan Wang ◽  
Alex Robertson ◽  
Jamie H. Warner
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Transition Metal ◽  
Atomic Structure ◽  
Transition Metal Dichalcogenides ◽  
Transmission Electron ◽  
Metal Dichalcogenides ◽  
Layered Transition Metal

Transmission electron microscopy can directly image the detailed atomic structure of layered transition metal dichalcogenides, revealing defects and dopants.

In situ Transmission Electron Microscopy Studies on Structural Dynamics of Transition Metal Nanoclusters

2005 ◽  
Vol 20 (7) ◽  
pp. 1785-1791 ◽  
Author(s):  
T. Vystavel ◽  
S.A. Koch ◽  
G. Palasantzas ◽  
J.Th.M. De Hosson
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
Transition Metal ◽  
Electron Beam Irradiation ◽  
Oxide Shell ◽  
Metal Nanoclusters ◽  
Beam Irradiation ◽  
Transmission Electron

The structural stability of transition metal nanoclusters has been scrutinized with in situ transmission electron microscopy as a function of temperature. In particular iron, cobalt, niobium, and molybdenum clusters with diameters around 5 nm have been investigated. During exposure to air, a thin oxide shell with a thickness of 2 nm is formed around the iron and cobalt clusters, which is thermally unstable under moderate high vacuum annealing above 200 °C. Interestingly, niobium clusters oxidize only internally at higher temperatures without the formation of an oxide shell. They are unaffected under electron beam irradiation, whereas iron and cobalt undergo severe structural changes. Further, no cluster coalescence of niobium takes place, even during annealing up to 800 °C, whereas iron and cobalt clusters coalesce after decomposition of the oxide, as long as the clusters are in close contact. In contrast to niobium, molybdenum clusters do not oxidize upon annealing; they are stable under electron beam irradiation and coalesce at temperatures higher than 800 °C. In all cases, the coalescence process indicates a strong influence of the local environment of the cluster.

Microstructural Investigation of RE3(Fe.V) 29 (RE = Nd, Tb) Magnetic Materials

1999 ◽  
Vol 577 ◽  
Author(s):  
J. Bernardi ◽  
M. Noner ◽  
J. Fidler ◽  
X.F. Han ◽  
F.M. Yang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Type Structure ◽  
X Ray Diffraction ◽  
Antiphase Boundaries ◽  
Microstructural Investigation ◽  
Space Group ◽  
X Ray ◽  
Arc Melting ◽  
Transmission Electron

ABSTRACTThe microstructure of V stabilized RE3(Fe,V)29 (RE=Nd,Tb) has been investigated by transmission electron microscopy (TEM). The investigated samples were prepared by arc melting and subsequent annealing above 910°C. X-ray diffraction confirms that the samples can be indexed based on a monoclinic Nd3(Fe,Ti)29-type structure (3:29) with A2/m space group. Our TEM investigation confirms that Nd3(Fe,V)29 contains usually grains with 3:29 structure and A 2/m space group. In addition grains with rhombohedral Th2Zn17 structure are observed regularly. The Tb3(FeV)29 alloy consists also of grains with monoclinic Nd3(Fe,Ti)29-type structure and contains a high density of planer defects like crystallographic twins or antiphase boundaries. Twinning occurs preferably on (402) of the monoclinic 3:29 structure. No tetragonal RE(Fe,V)12 phase or Fe is found.

DEFECTS OF A15 SMALL PARTICLES IN TUNGSTEN THIN FILMS

1996 ◽  
Vol 03 (01) ◽  
pp. 1191-1194 ◽  
Author(s):  
MASASHI ARITA ◽  
ISAO NISHIDA
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Crystal Defects ◽  
Type Structure ◽  
Special Structure ◽  
Small Particles ◽  
Structure Unit ◽  
Transmission Electron ◽  
Means Of Transmission

Crystal defects of A15 small particles in tungsten thin films were studied by means of transmission electron microscopy. Defects found in nanoscale crystals were analyzed to have special structure containing the Zr4Al3-type structure unit.

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