Characterization of short-period Sim Gen superlattices by high-resolution transmission electron microscopy and X-ray diffraction

1992 ◽  
Vol 222 (1-2) ◽  
pp. 221-226 ◽  
Author(s):  
W. Jäger ◽  
D. Stenkamp ◽  
P. Ehrhart ◽  
K. Leifer ◽  
W. Sybertz ◽  
...  
1995 ◽  
Vol 399 ◽  
Author(s):  
M. Shima ◽  
L. Salamanca-Riba ◽  
G. Springholz ◽  
G. Bauer

ABSTRACTMolecular beam epitaxy was used to grow EuTe(x)/PbTe(y) short period superlattices with x=1-4 EuTe(111) monolayers alternating with y≈3x PbTe monolayers. The superlattices were characterized by transmission electron microscopy and high resolution x-ray diffraction. Regions with double periodicity were observed coexisting with areas of nominal periodicity. The sample with x=3.5 and y=9, for example, contains regions with double periodicity of x=7 and y=17. X-ray diffraction measurements confirm the formation of the double periodicity in these samples by the appearance of weak satellites in between the satellites of the nominal periodicity. The double periodicity in the superlattice is believed to result from interdiffusion during the growth. A model for this process is presented.


2005 ◽  
Vol 19 (15n17) ◽  
pp. 2508-2513 ◽  
Author(s):  
JIANMIN ZHU ◽  
SHISONG HUANG ◽  
GUOBIN MA ◽  
NAIBEN MING

By means of sonochemical method, Fe 3 O 4 and ZnFe 2 O 4 nanocrystallines can be synthesized from FeCl 2/ urea and ZnCl 2/ FeCl 2/ urea in water. The products were characterized by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM) as well as selected area electron diffraction (SAED). Special attention was paid to the microstructure of the nanocrystallines using high-resolution transmission electron microscopy (HREM). Probable mechanisms for the sonochemical formation of Fe 3 O 4 and ZnFe 2 O 4 nanocrystallines are discussed.


1991 ◽  
Vol 220 ◽  
Author(s):  
W. Jäger ◽  
K. Leifer ◽  
P. Ehrhart ◽  
E. Kasper ◽  
H. Kibbel

ABSTRACTHigh resolution and analytical transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to characterize short-period strained-layer Sim-Gen superlattices ( m monolayers Si, n monolayers Ge, total number of periods N≤ 145, total thickness ≃ 200 nm). The superlattices were grown by low-temperature molecular beam epitaxy (T = 300–400°C) on different SiGe alloy buffer layers on Si (100)substrates. The combination of these two methods shows that detailed informations can be obtained about superlattice periodicity, interface roughness, strain, and average composition.


Author(s):  
R. Gronsky

The phenomenon of clustering in Al-Ag alloys has been extensively studied since the early work of Guinierl, wherein the pre-precipitation state was characterized as an assembly of spherical, ordered, silver-rich G.P. zones. Subsequent x-ray and TEM investigations yielded results in general agreement with this model. However, serious discrepancies were later revealed by the detailed x-ray diffraction - based computer simulations of Gragg and Cohen, i.e., the silver-rich clusters were instead octahedral in shape and fully disordered, atleast below 170°C. The object of the present investigation is to examine directly the structural characteristics of G.P. zones in Al-Ag by high resolution transmission electron microscopy.


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