scholarly journals Numerical study of the electronic structure of amorphous silica

1997 ◽  
Vol 56 (15) ◽  
pp. 9469-9476 ◽  
Author(s):  
Thorsten Koslowski ◽  
Walter Kob ◽  
Katharina Vollmayr
Keyword(s):  
Electronic Structure ◽  
Amorphous Silica ◽  
Numerical Study

Reassessment of the Electronic Structure of Cr(VI) Sites Supported on Amorphous Silica and Implications for Cr Coordination Number

2018 ◽  
Vol 122 (8) ◽  
pp. 4349-4358 ◽  
Author(s):  
Nathan M. Peek ◽  
David B. Jeffcoat ◽  
Cristina Moisii ◽  
Lambertus van de Burgt ◽  
Salvatore Profeta ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Coordination Number ◽  
Amorphous Silica

Electronic structure of molybdenum-involved amorphous silica buffer layer in MoOx/n-Si heterojunction

2019 ◽  
Vol 473 ◽  
pp. 20-24 ◽  
Author(s):  
Dongyun Chen ◽  
Ming Gao ◽  
Yazhou Wan ◽  
Yonghua Li ◽  
Haibo Guo ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Buffer Layer ◽  
Amorphous Silica

scholarly journals First principle study of ternary combined-state and electronic structure in amorphous silica

2017 ◽  
Vol 66 (18) ◽  
pp. 188802
Author(s):  
Wan Ya-Zhou ◽  
Gao Ming ◽  
Li Yong ◽  
Guo Hai-Bo ◽  
Li Yong-Hua ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Amorphous Silica ◽  
First Principle

Amorphous silica coating on α-alumina particles

1995 ◽  
Vol 53 ◽  
pp. 210-211
Author(s):  
J. W. Mellowes ◽  
C. M. Chun ◽  
I. A. Aksay
Keyword(s):  
Amorphous Silica ◽  
Heterogeneous Nucleation ◽  
Homogeneous Nucleation ◽  
Silica Coating ◽  
Full Density ◽  
Optimal Conditions ◽  
Fine Grained ◽  
Alumina Particles ◽  
Complete Mullitization ◽  
Powder Compacts

Mullite (3Al2O32SiO2) can be fabricated by transient viscous sintering using composite particles which consist of inner cores of a-alumina and outer coatings of amorphous silica. Powder compacts prepared with these particles are sintered to almost full density at relatively low temperatures (~1300°C) and converted to dense, fine-grained mullite at higher temperatures (>1500°C) by reaction between the alumina core and the silica coating. In order to achieve complete mullitization, optimal conditions for coating alumina particles with amorphous silica must be achieved. Formation of amorphous silica can occur in solution (homogeneous nucleation) or on the surface of alumina (heterogeneous nucleation) depending on the degree of supersaturation of the solvent in which the particles are immersed. Successful coating of silica on alumina occurs when heterogeneous nucleation is promoted and homogeneous nucleation is suppressed. Therefore, one key to successful coating is an understanding of the factors such as pH and concentration that control silica nucleation in aqueous solutions. In the current work, we use TEM to determine the optimal conditions of this processing.

EELS Measurement of the Local Electronic Structure of Copper Atoms Segregated to Aluminum Grain Boundaries

1996 ◽  
Vol 54 ◽  
pp. 342-343
Author(s):  
S.J. Splinter ◽  
J. Bruley ◽  
P.E. Batson ◽  
D.A. Smith ◽  
R. Rosenberg
Keyword(s):  
Electronic Structure ◽  
Grain Boundaries ◽  
Boundary Segregation ◽  
Thin Layers ◽  
Nominal Composition ◽  
Spatially Resolved ◽  
Service Lifetime ◽  
Heat Treated ◽  
Probe Size ◽  
Local Electronic Structure

It has long been known that the addition of Cu to Al interconnects improves the resistance to electromigration failure. It is generally accepted that this improvement is the result of Cu segregation to Al grain boundaries. The exact mechanism by which segregated Cu increases service lifetime is not understood, although it has been suggested that the formation of thin layers of θ-CuA12 (or some metastable substoichiometric precursor, θ’ or θ”) at the boundaries may be necessary. This paper reports measurements of the local electronic structure of Cu atoms segregated to Al grain boundaries using spatially resolved EELS in a UHV STEM. It is shown that segregated Cu exists in a chemical environment similar to that of Cu atoms in bulk θ-phase precipitates.Films of 100 nm thickness and nominal composition Al-2.5wt%Cu were deposited by sputtering from alloy targets onto NaCl substrates. The samples were solution heat treated at 748K for 30 min and aged at 523K for 4 h to promote equilibrium grain boundary segregation. EELS measurements were made using a Gatan 666 PEELS spectrometer interfaced to a VG HB501 STEM operating at 100 keV. The probe size was estimated to be 1 nm FWHM. Grain boundaries with the narrowest projected width were chosen for analysis. EDX measurements of Cu segregation were made using a VG HB603 STEM.

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