Implications of Interface Structure on the Elastic Properties of Metallic Multilayers-The Case of the Supermodulus Effect

1991 ◽  
Vol 229 ◽  
Author(s):  
Alan F. Jankowski

AbstractThe existence of the supermodulus effect, an enhancement in the elastic modulus of artificially layered metal films, was discovered more than a dozen years ago. Yet the detailed nature of this effect remains a puzzling phenomena. Implications of the interface structure on the elastic properties of gold-nickel multilayers are investigated using x-ray diffraction and high resolution electron microscopy.

1995 ◽  
Vol 398 ◽  
Author(s):  
A. Tomasi ◽  
E. Galvanetto ◽  
F.C. Matacotta ◽  
P. Nozar ◽  
P. Scardi ◽  
...  

ABSTRACTA systematic study on phase formation and stabilisation in the Ba-Cu-C-O system in the temperature range 20-500°C, under various atmospheres, by traditional thermal analysis techniques, high temperature X-ray diffraction and high resolution electron microscopy, has permitted to identify and characterise the formation kinetics of a new copper containing phase isomorphic to γ-BaCO3.


1992 ◽  
Vol 7 (6) ◽  
pp. 1356-1369 ◽  
Author(s):  
B.M. Davis ◽  
D.X. Li ◽  
D.N. Seidman ◽  
J.B. Ketterson ◽  
R. Bhadra ◽  
...  

A series of Cu/Pd superlattices with composition modulation wavelengths (Λ's) ranging from 1.6 to 3.5 nm and a strong [111] growth texture were prepared by electron beam evaporation. The elastic properties of the films were examined using the methods of uniaxial tension tests [a Young's modulus (1/s11), where sij is an elastic compliance] with the applied load parallel to the plane of the Cu/Pd interface and Brillouin scattering [a shear modulus (1/s44) with the shear waves parallel to the plane of the Cu/Pd interface]. Also, the films were characterized using both x-ray diffraction and high-resolution electron microscopy; this was done to assess the effect of the nanostructure on a possible “supermodulus effect.” The films are nanostructurally very similar to the superlattice films employed in previous studies at Northwestern in which a supermodulus effect was reported. But, contrary to previous studies, no anomalous behavior was observed for the measured elastic properties of the thin films. Therefore the present results negate the earlier results and cast a serious doubt on the existence of a supermodulus effect.


Author(s):  
A. Legrouri

The oxides of vanadium, especially vanadium pentoxide, have been extensively studied because of their interesting physical properties particularly in catalysis. Vanadium pentoxide is generally used in the oxidation and ammoxidation of hydrocarbons.This catalyst has been prepared via the thermal decomposition of ammonium metavanadate (AMV) in air. Thermogravimetric analysis (TGA), infrared spectroscopy (IRS) and x-ray diffraction (XRD) techniques together with high resolution electron microscopy (HREM) and scanning electron microscopy (SEM) have enabled us to elucidate the physicochemical changes occurring during the decomposition process.According to TGA results, the decomposition of AMV commences at 150°C and is complete by 320°C leading to vanadium pentoxide by loss of ammonia and water with the formation of two intermediate compounds, namely at 190°C, ammonium bivanadate: (NH4)2V4 O11, and at 230°C, ammonium hexavanadate AHV: (NH4)2V6O16 . Samples for structural correlation studies were prepared by heating AMV in a stream of air for 2 hours at selected temperatures of 140, 190, 230, 320 and 400°C.


1997 ◽  
Vol 3 (S2) ◽  
pp. 441-442
Author(s):  
P.A. Crozier ◽  
I.Y. Chan ◽  
C.Y. Chen ◽  
L.W. Finger ◽  
R.C. Medrud ◽  
...  

Low-dose high resolution electron microscopy (HREM) is a useful technique for elucidating the structure of zeolites. In recent years a number of zeolite structures have been solved using combinations of different characterization techniques including adsorption measurements, powder x-ray diffraction and low-dose high resolution electron microscopy (for example see ref. 2). We have used these techniques to study the structure of a novel zeolite material. However, great care must be exercised when interpreting data from these techniques in terms of crystal structural units. In this particular case, the structure was recently determined using single crystal x-ray diffraction and showed some surprises.Details of the synthesis of this zeolite are given elsewhere. The high adsorption capacity suggested that this zeolite possessed two interpenetrating channels (either a 10 and a 12 ring or two 12 ring channels). X-ray powder diffraction showed the material to be monoclinic with a= 18.5Å, b= 13.4 Å, c= 7.6 Å β = 101.5°).


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