Transmission Electron Microscopy study of lead sulfide whiskers

Author(s):  
S.A. Mansour ◽  
R. Scholz

This paper describes a transmission electron microscopy (TEM) study of the structure and growth mechanism of lead sulfide (PbS) whiskers. PbS whiskers were grown inside the stainless steel nozzle of a kerosene burner. The nozzle had a 0.5 mm aperture, and was fitted with an Al-spiral coil to filter kerosene impurities. The burner was operated continuously for four weeks at a kerosene pressure of 2-3 bars and a flame temperature of about 350°C before the nozzle clogged. A thick black deposit of fine PbS whiskers was found inside the nozzle.TEM specimens were prepared by ultrasonically suspending the fine black powder in alcohol. The suspended particles were deposited on a perforated carbon film supported on a copper grid, and examined with a JEM-1200EX transmission electron microscope operated at 120kV accelerating voltage. A JEM-4000EX transmission electron microscope was used for high resolution electron microscopy.Fig. 1. shows an EM micrograph of typical PbS whiskers. Each appears to have a high-contrast core encapsulated in a lower contrast shell. The electron diffraction pattern of a single whisker protruding over a hole in the carbon film is shown in Fig. 2.

1985 ◽  
Vol 54 ◽  
Author(s):  
Taeil Kim ◽  
D.D.L. Chung

ABSTRACTThe structure of 500 Å Au/500 A Ge/500 Å Au/GaAs (100) was studied by transmission electron microscopy after annealing at 350 – 500°C. Annealing at 350 – 450°C caused the formation of AuGeAs with a (110) texture, but this phase disappeared after annealing at 500°C. The hexagonal a-AuGa (or AuGa) was formed after annealing at 400°C, such that (111)Au // (0001)a, and [110]AU // [1120]a and there was perfect lattice match between Au (i.e., Au-rich solid solution) and a-AuGa. After annealing at 450°C or above, a phase tentatively identified as the hexagonal Au3Ga was formed and Ge (i.e., Ge-rich solid solution) became epitaxial to (100) GaAs. Annealing at 400°C caused Au to change from no texture to a (110) texture.


2002 ◽  
Vol 8 (6) ◽  
pp. 497-501 ◽  
Author(s):  
Yong J. Suh ◽  
Sergey V. Prikhodko ◽  
Sheldon K. Friedlander

Experimental difficulties in studying nanostructures stem from their small size, which limits the use of traditional techniques for measuring their physical properties. We have developed a nanostructure manipulation device to apply tension to chain aggregates mounted in a transmission electron microscope. A 1-mm-long slit was cut in the center of a lead–tin alloy disc, measuring 3 mm in diameter and 200 μm in thickness. The disc was heated to about 140°C before it was pressed between two quartz slides. The disc was then thinned by mechanical dimpling and ion milling until holes developed around the slit. The edges of the slit were 0.2 to 3 μm in thickness while the gap between them was up to a few microns. This disc was bonded to the two plates of a cartridge. The slit could be widened or narrowed at controlled speeds of 0.5 to 300 nm/s. The system was tested using titania (TiO2) nanoparticle chain aggregates (NCA) deposited across the slit. The ends of the NCA remained attached to the edges of the slit, which was widened at about 0.7 nm/s. In this way, the NCA was stretched up to 176% of its initial length before breaking.


1994 ◽  
Vol 27 (5) ◽  
pp. 762-766 ◽  
Author(s):  
Q. Liu

With aid of a transmission-electron-microscope (TEM) double-tilt holder, a method for determining the normals to planar structures and their traces in a TEM is developed. This method is considered to be simple and convenient when compared with other methods. The accuracy of the method for the determination of both the normals to planar structures and their traces is within 2°.


Author(s):  
Ray L. Withers ◽  
Lasse Norén ◽  
Yun Liu

AbstractA review of the application of transmission electron microscopy to the study of interface, composite and displacively modulated structures is given. The distinctly different mechanisms underlying structural modulation in each case are emphasized as is the practical application of transmission electron microscopy to problems such as pseudo-symmetry and twinning, to indexation in (3 +


1992 ◽  
Vol 70 (11) ◽  
pp. 2223-2232 ◽  
Author(s):  
S. J. Read ◽  
S.-Y. Hsieh ◽  
E. B. G. Jones ◽  
S. T. Moss ◽  
H. S. Chang

A collection of Paraliomyces lentiferus from Taiwan, Republic of China, is compared with that of the type description and examined at both scanning and transmission electron microscope levels as part of our review of the taxonomy of the marine Ascomycotina. Particular attention was devoted to the structure of the ascospore appendage. The ascospore wall comprises a mesosporium, an episporium, and a mucilaginous sheath (exosporium?) In addition, there is a single, gelatinous, lateral appendage adjacent to the central septum. The appendage comprises electron-opaque fibrils that in immature ascospores are connected to the ascospore wall via fine electron-opaque strands and larger electron-opaque aggregates of material. The origin of the appendage is discussed. Key words: ascospore, attachment, marine ascomycete, scanning electron microscopy, spore appendage, transmission electron microscopy.


1984 ◽  
Vol 62 (10) ◽  
pp. 2081-2093 ◽  
Author(s):  
Rosmarie Honegger

The conidiomata, conidiophores, and conidia of six lichen-forming Ascomycetes were investigated using the scanning electron microscope, and conidium development in two of these species was studied by transmission electron microscopy. Phialidic (micro) conidium formation was observed in the mycobiont of Parmelia tiliacea, Physconia pulverulacea, and Cladonia furcata (Lecanorales), in Lobaria laetevirens (Peltigerales), and in Caloplaca aurantia (Teloschistales). Annellations, first described by Vobis on the basis of light and transmission electron microscope investigations, were also found in scanning electron microscope preparations of macroconidia bearing conidiogenous cells of Lecanactis abietina (Opegraphales). Ultrastructural and developmental studies on conidiophore structure and conidium formation may be of interest for taxonomic and evolutionary considerations in lichen-forming fungi.


1987 ◽  
Vol 99 ◽  
Author(s):  
Shozo Ikeda ◽  
Kazuhiro Kimura ◽  
Akiyuki Matsushita ◽  
Haruyoshi Aoki ◽  
Takeshi Hatano ◽  
...  

ABSTRACTWe studied grain boundaries in calcined and sintered YBa2Cu3Ox transmission electron microscopy (TEM) and found complex Ba-Cu oxides. The complex oxide was polycrystalline and composed of grains smaller than 100 nm in diameter and it often included minor phases rich in Y. Some stoichiomet-ric oxides such as BaCuO2, CuO and BaO were also observed along grain boundaries.


Author(s):  
N. Tanaka ◽  
K. Mihama ◽  
H. Ou ◽  
J.M. Cowley

Nanometer-sized iron(Fe) crystallites can be prepared in a single crystalline magnesium oxide(MgO) film by a simultaneous vacuum deposition of Fe and MgO. The crystallites are grown epitaxially and almost coherently in the film, the orientation being (001) [110]Fe//(001)[100]MgOand (011) [100]Fe//(001) [100]MgO. A heat treatment of the as-grown composite films at 500-1000°C brings about a phase-transformation from α -iron(b.c.c.) to γ -iron(f.c.c.). In the present study, the phase-transformation and the structure of the γ-iron crystallites are studied by nanometer-area electron diffraction(nanodiffraction) in TEM and STEM as well as high-resolution electron microscopy.The specimens were single crystalline Fe-MgO composite films prepared on a NaCl (001 ) surface by co-evaporation of Fe and MgO. The films were separated from the substrate in water and mounted on a perforated carbon film. Nanodiffraction in TEM was performed in a 200 kV transmission electron microscope(JEM- 2000FX)2 and that in STEM3was carried out in a 100 kV scanning transmission electron microscope (VG-HB5) equipped with a specimen-preparation chamber.


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