The use of high-resolution FESEM to study solid-state phase transformations and reactions

High-resolution field-emission-gun scanning electron microscopy (FESEM) has recently emerged as an extremely powerful method for characterizing the micro- or nanostructure of materials. The development of high efficiency backscattered-electron detectors has increased the resolution attainable with backscattered-electrons to almost that attainable with secondary-electrons. This increased resolution allows backscattered-electron imaging to be utilized to study materials once possible only by TEM. In addition to providing quantitative information, such as critical dimensions, SEM is more statistically representative. That is, the amount of material that can be sampled with SEM for a given measurement is many orders of magnitude greater than that with TEM.In the present work, a Hitachi S-900 FESEM (operating at 5kV) equipped with a high-resolution backscattered electron detector, has been used to study the α-Fe2O3 enhanced or seeded solid-state phase transformations of sol-gel alumina and solid-state reactions in the NiO/α-Al2O3 system. In both cases, a thin-film cross-section approach has been developed to facilitate the investigation. Specifically, the FESEM allows transformed- or reaction-layer thicknesses along interfaces that are millimeters in length to be measured with a resolution of better than 10nm.

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Interfacial precipitation in titania-doped diphasic mullite gels

Journal of Materials Research ◽

10.1557/jmr.1998.0136 ◽

1998 ◽

Vol 13 (4) ◽

pp. 974-978 ◽

Cited By ~ 4

Author(s):

Seong-Hyeon Hong ◽

Naesung Lee ◽

Altaf H. Carim ◽

Gary L. Messing

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

High Resolution ◽

Phase Transformations ◽

Orientation Relationship ◽

Sol Gel ◽

Sintered Body ◽

Transmission Electron

Interfacial precipitation in sol-gel derived, titania-doped diphasic mullite gels was investigated using conventional and high resolution transmission electron microscopy. Rutile, anatase, and brookite precipitated on the interface between {110} planes of mullite and glass pockets in the sintered body. The formation of brookite may be attributable to the Si- and Al-rich environment during precipitation. Each polymorph of titania has a unique morphology and orientation relationship with mullite. Brookite exhibits a truncated pill box shape, and anatase displays a vermicular morphology. Quenching experiments suggest that the precipitates grow and undergo phase transformations during cooling.

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Synthesis and Characterization of CaMgSi2O6 Activated by Eu2+

Materials Science Forum ◽

10.4028/www.scientific.net/msf.881.30 ◽

2016 ◽

Vol 881 ◽

pp. 30-34

Author(s):

Agatha Matos Misso ◽

Hermi F. Brito ◽

Lucas C.V. Rodrigues ◽

Vinicius R. Morais ◽

Chieko Yamagata

Keyword(s):

High Efficiency ◽

Low Cost ◽

Sol Gel ◽

Solid State Reactions ◽

Phase Identification ◽

Molten Salt Method ◽

Persistent Luminescence ◽

Light Emitting ◽

Fluorescent Lamps ◽

White Light Emitting Diodes

Rare earth silicate based MnMgSi2O5+n (M = Ca, Sr or Ba and n=1-2) phosphors, have attracted interest of researchers due to their high efficiency as a host, excellent thermal and chemical stability and high brightness adding to their low cost. These phosphors showed great potential in various applications such as fluorescent lamps, white light emitting diodes, and display components. High temperature solid-state reactions are usually employed to synthesize those compounds. This paper proposes an alternative method of obtaining nanophosphor host based on Eu-doped CaMgSi2O6 (CMS:Eu), persistent luminescence phosphor. Sol gel technique combined to a modified molten salt method was used. The resulted powder was calcined for 3h under an atmosphere of 5% H2 and 95% Ar2. Phase identification by XRD and the measurements of photoluminescence (PL) and photoluminescence excitation (PLE) were performed. Single phased CMS:Eu with persistent luminescence characteristics was prepared.

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Visibility of Small Metalllic Catalyst Particles in High-Resolution Secondary and Backscattered Electron Images

Microscopy and Microanalysis ◽

10.1017/s1431927600016925 ◽

1999 ◽

Vol 5 (S2) ◽

pp. 720-721

Author(s):

Jingyue Liu

Keyword(s):

High Resolution ◽

Metallic Nanoparticles ◽

Low Voltage ◽

High Surface ◽

High Surface Area ◽

Metal Catalyst ◽

Catalyst Supports ◽

Metallic Particles ◽

Backscattered Electrons ◽

Backscattered Electron

Metallic nanoparticles finely dispersed onto high surface-area supports play an important role in heterogeneous catalysis. The performance of a supported metal catalyst can be directly related to the size and spatial distribution of the metallic nanoparticles. With the recent development of highresolution SEM instruments, it is now possible to observe nanoparticles in a field emission SEM. At low voltages, surface details of catalyst supports as well as metallic nanoparticles can be observed. The particle contrast in low voltage SEM images, however, is still not well understood. We have previously shown that the contrast of metallic particles can be enhanced if a small positive potential is applied to the sample. It is suggested that backscattered electrons (BE) significantly contribute to the visibility of metallic nanoparticles in high-resolution SE images. In this paper, we report further study on the origin of particle contrast in high-resolution SE images.Figure 1 shows a set of SE images of the same area of a carbon supported Pt catalyst.

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On synthesis of Fe2SiO4/SiO2 and Fe2O3/SiO2 composites through sol–gel and solid-state reactions

Journal of Sol-Gel Science and Technology ◽

10.1007/s10971-014-3483-5 ◽

2014 ◽

Vol 72 (3) ◽

pp. 602-614 ◽

Cited By ~ 21

Author(s):

Chuanlong Wang ◽

Leon L. Shaw

Keyword(s):

Solid State ◽

Sol Gel ◽

Solid State Reactions

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Quantitative Analysis in High Resolution Transmission Scanning Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100064177 ◽

1971 ◽

Vol 29 ◽

pp. 24-25

Author(s):

A. V. Crewe ◽

J. Wall

Keyword(s):

Quantitative Analysis ◽

High Resolution ◽

Cross Sections ◽

High Efficiency ◽

High Spatial Resolution ◽

Incident Beam ◽

Quantitative Information ◽

Additive Functions ◽

Scanning Microscope ◽

Scattering Cross Sections

The scanning microscope is ideally suited for gathering quantitative information about an object, since its outputs are voltage signals which are measures of the interactions of the incident beam with the volume of the specimen struck by the beam. These signals vary in real time as the beam scans and can be processed electronically to assign a “number” to each element of the scanned matrix.Elastic and inelastic scattering cross sections have been selected as the two useful numbers to characterize a specimen since both are 1) additive functions of specimen composition, 2) unambiguously measurable with high efficiency, 3) Independent of microscope parameters, and 4) measurable with high spatial resolution (<5Å).

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Multi-purpose backscattered electron detector

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100107551 ◽

1978 ◽

Vol 36 (1) ◽

pp. 82-83

Author(s):

M. Kikuchi ◽

S. Takashima

Keyword(s):

Solid State ◽

Magnetic Domain ◽

High Sensitivity ◽

Solid State Detector ◽

Response Characteristics ◽

Backscattered Electrons ◽

Backscattered Electron ◽

Takeoff Angle ◽

Z Contrast ◽

State Detector

Backscattered electrons (BSE) permit a variety of information regarding the specimen, e.g., composition, topography, magnetic domain structure, crystalline states, etc., to be obtained. However, since conventional BSE detectors are all single-purpose designed, several different detectors are required to obtain the required variety of information.In order to circumvent this inconvenience, we have developed a multi-purpose BSE detector system. As shown in Fig. 1, the detector can be freely rotated around the specimen surface. In addition to which, the distance between the detector and the specimen can be varied. The newly developed solid state detector used in this system possesses high sensitivity and high response characteristics. Some advantages and applications of the system are given below.1. By setting the detector at the low and high takeoff angle positions, topographic contrast and composite contrast (Z-contrast) can be respectively enhanced.2. By using the rotation and distance varing mechanisms in combination, the optimum detecting condition for ensuring a good magnetic domain image can be selected.

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Analysis of Interface Dynamics in Solid-State Phase Transformations by In Situ Hot-Stage High-Resolution Transmission Electron Microscopy

MRS Proceedings ◽

10.1557/proc-332-65 ◽

1994 ◽

Vol 332 ◽

Cited By ~ 1

Author(s):

James M. Howe ◽

W. E. Benson ◽

A. Garg ◽

Y.-C. Chang

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Solid State ◽

High Resolution ◽

Phase Transformations ◽

Interface Motion ◽

Transmission Electron ◽

Kinetics Of ◽

Dynamics Of Interfaces

ABSTRACTIn situ hot-stage high-resolution transmission electron microscopy (HRTEM) provides unique capabilities for quantifying the dynamics of interfaces at the atomic level. Such information is critical for understanding the theory of interfaces and solid-state phase transformations. This paper provides a brief description of particular requirements for performing in situ hot-stage HRTEM, summarizes different types of in situ HRTEM investigations and illustrates the use of this technique to obtain quantitative data on the atomic mechanisms and kinetics of interface motion in precipitation, crystallization and martensitic reactions. Some limitations of in situ hot-stage HRTEM and future prospects of this technique are also discussed.

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