Measuring Electrostatic Potential Profiles across Amorphous Intergranular Films by Electron Diffraction

Koch, Christoph T.; Bhattacharyya, Somnath; Rühle, M.; Hoffmann, Michael J.

doi:10.1017/s1431927606060132

Cited by 6 publications

(6 citation statements)

References 26 publications

(16 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…4d is À16.7 V. This experimentally determined mean inner potential of Si 3 N 4 is in good agreement with the calculated value (À17.4 V [4]). The discrepancy between the calculated and reconstructed mean inner potential, depends on a good estimate of the IMFP of Si 3 N 4 (essential for accurate specimen thickness determination) as well as the scattering factors (for neutral or charged atoms) used for the evaluation of Eq.…”

Section: Article In Presssupporting

confidence: 89%

“…The formation of a particular specially shaped potential profile across GaAs devices is probably caused by charge trapping at the interface between the epitaxial layer and the substrate [3]. Potential profiles across intergranular glassy films in polycrystalline ceramics may provide information regarding structural and compositional changes across that grain boundary [4]. In general, potential profiles across interfaces can provide useful information about their structure, composition, density, ionicity of their constituents, the presence of space charge layers, etc., showing that the ability to measure potential profiles across interfaces is of great importance in the field of material science.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Projected potential profiles across interfaces obtained by reconstructing the exit face wave function from through focal series

Bhattacharyya¹,

Koch²,

Rühle³

2006

Ultramicroscopy

Self Cite

View full text Add to dashboard Cite

Section: Article In Presssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Projected potential profiles across interfaces obtained by reconstructing the exit face wave function from through focal series

Bhattacharyya¹,

Koch²,

Rühle³

2006

Ultramicroscopy

Self Cite

View full text Add to dashboard Cite

“…However, such data are difficult to obtain by any other means. In the work by Koch et al, 78 x-ray or electron-diffraction techniques were used which depend on the charge density and hence electrostatic potential of the samples. They reported the reconstruction of a one-dimensional potential profile across an IGF from an energy-filtered electron-diffraction pattern.…”

Section: Discussionmentioning

confidence: 99%

Theoretical study of the elasticity, mechanical behavior, electronic structure, interatomic bonding, and dielectric function of an intergranular glassy film model in prismaticβ-Si3N4

et al. 2010

View full text Add to dashboard Cite

Microstructures such as intergranular glassy films ͑IGFs͒ are ubiquitous in many structural ceramics. They control many of the important physical properties of polycrystalline ceramics and can be influenced during processing to modify the performance of devices that contain them. In recent years, there has been intense research, both experimentally and computationally, on the structure and properties of IGFs. Unlike grain boundaries or dislocations with well-defined crystalline planes, the atomic scale structure of IGFs, their fundamental electronic interactions, and their bonding characteristics are far more complicated and not well known. In this paper, we present the results of theoretical simulations using ab initio methods on an IGF model in ␤-Si 3 N 4 with prismatic crystalline planes. The 907-atom model has a dimension of 14.533 Å ϫ 15.225 Å ϫ 47.420 Å. The IGF layer is perpendicular to the z axis, 16.4 Å wide, and contains 72 Si, 32 N, and 124 O atoms. Based on this model, the mechanical and elastic properties, the electronic structure, the interatomic bonding, the localization of defective states, the distribution of electrostatic potential, and the optical dielectric function are evaluated and compared with crystalline ␤-Si 3 N 4 . We have also performed a theoretical tensile experiment on this model by incrementally extending the structure in the direction perpendicular to the IGF plane until the model fully separated. It is shown that fracture occurs at a strain of 9.42% with a maximum stress of 13.9 GPa. The fractured segments show plastic behavior and the formation of surfacial films on the ␤-Si 3 N 4 . These results are very different from those of a previously studied basal plane model ͓J. Chen et al., Phys. Rev. Lett. 95, 256103 ͑2005͔͒ and add insights to the structure and behavior of IGFs in polycrystalline ceramics. The implications of these results and the need for further investigations are discussed.

show abstract

“…The profile (P) has two Gaussian functions (replacing the vertical sections of a square‐well potential) to describe the diffuseness of the crystal–glass interface. The depth of the potential profile was chosen as that between Si 3 N 4 (17.4 V) and SiO 2 (10.9 V) (Peng, 1999; Koch et al ., 2005). Figure 2(b) shows the FT of the profile in Fig.…”

Section: Fourier Filteringmentioning

confidence: 99%

Aspects regarding measurement of thickness of intergranular glassy films

Bhattacharyya¹,

Subramaniam²,

Koch³

et al. 2006

Journal of Microscopy

View full text Add to dashboard Cite

Summary Materials such as Si3N4, SiC and SrTiO3 can have grain boundaries characterized by the presence of a thin intergranular amorphous film of nearly constant thickness, in some cases (e.g. Si3N4) almost independent of the orientation of the bounding grains, but dependent on the composition of the ceramic. Microscopy techniques such as high‐resolution lattice fringe imaging, Fresnel fringe imaging and diffuse dark field imaging have been applied to the study of intergranular glassy films. The theme of the current investigation is the use of Fresnel fringes and Fourier filtering for the measurement of the thickness of intergranular glassy films. Fresnel fringes hidden in high‐resolution micrographs can be used to objectively demarcate the glass–crystal interface and to measure the thickness of intergranular glassy films. Image line profiles obtained from Fourier filtering the high‐resolution micrographs can yield better estimates of the thickness. Using image simulation, various kinds of deviation from an ideal square‐well potential profile and their effects on the Fresnel image contrast are considered. A method is also put forth to objectively retrieve Fresnel fringe spacing data by Fourier filtering Fresnel contrast images. Difficulties arising from the use of the standard Fresnel fringe extrapolation technique are outlined and an alternative method for the measurement of the thickness of intergranular glassy films, based on zero‐defocus (in‐focus) Fresnel contrast images is suggested. The experimental work is from two ceramic systems: Lu‐Mg‐doped Si3N4 and SrTiO3 (stoichiometric and nonstoichiometric). Further, a comparison is made between the standard high‐resolution lattice fringe technique, the standard Fresnel fringe extrapolation technique and the methods of analyses introduced in the current work, to illustrate their utility and merits. Taking experimental difficulties into account, this work is intended to be a practical tool kit for the study of intergranular glassy films.

show abstract

Measuring Electrostatic Potential Profiles across Amorphous Intergranular Films by Electron Diffraction

Cited by 6 publications

References 26 publications

Projected potential profiles across interfaces obtained by reconstructing the exit face wave function from through focal series

Projected potential profiles across interfaces obtained by reconstructing the exit face wave function from through focal series

Theoretical study of the elasticity, mechanical behavior, electronic structure, interatomic bonding, and dielectric function of an intergranular glassy film model in prismaticβ-Si3N4

Aspects regarding measurement of thickness of intergranular glassy films

Contact Info

Product

Resources

About