Reciprocal Space X-Ray Mapping and Transmission Electron Microscopic Studies of Coincided δ-Inas and As-Cluster Superlattices in Gaas Films Grown by Molecular-Beam Epitaxy at Low Temperature

1999 ◽  
Vol 583 ◽  
Author(s):  
V. V. Chaldyshev ◽  
N. A. Bert ◽  
N. N. Faleev ◽  
Yu. G. Musikhin ◽  
A. E. Kunitsyn ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Reciprocal Space ◽  
Growth Surface ◽  
Electron Microscopic ◽  
Extended Defect ◽  
X Ray ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Interference Picture

AbstractInAs/GaAs superlattices with thin (0.5–1 monolayer) δ-InAs insertions were grown by molecular beam epitaxy at low (150–200°C) temperature. The as-grown samples contained up to 1020 cm−3 arsenic antisite defects. Transmission electron microscopic study revealed no extended defect and showed that the real thickness of δ-InAs insertions is 3–4 monolayers. This thickness seems to be due to short-range roughness of the growth surface. Low diffuse scattering and extended interference picture were observed for such superlattices by x-ray diffraction study. Superlattices of two-dimensional cluster sheets were produced by annealing of the δ-InAs/GaAs superlattices at 500–600°C. Precipitation of excess arsenic at InAs δ-layers was found to be accompanied by enhanced In-Ga intermixing, roughening the InAs δ-layers, and smoothing the x-ray interference picture. No evidence for any self-ordering in the system of nanoscale As clusters was revealed using x-ray mapping in reciprocal space.

Single Variant Orientational Growth of Yba2Cu3O7-x on Vicinal (011) SrTiO3 Substrates.

1995 ◽  
Vol 401 ◽  
Author(s):  
A. L. Vasiliev ◽  
D. S. Linehan ◽  
E. P. Kvam ◽  
L. Hou ◽  
M. W. McElfresh
Keyword(s):  
Second Phase ◽  
Surface Cracks ◽  
Electron Microscopic ◽  
Ybco Films ◽  
Single Crystalline ◽  
X Ray ◽  
Transmission Electron ◽  
Transmission Electron Microscopic

AbstractThe results of a transmission electron microscopic (TEM) and X-ray microanalysis (EDS) study of Yba2Cu3O7-x (YBCO) films grown on vicinal (011) SrTiO3 substrates are presented. The YBCO films tend to be single crystalline grown in single variant orientation with c-axis =;45° from the surface. Cracks, second phase precipitates (CuO and Y2O3), and a few small YBCO grains in other orientations were revealed in the films.

Synthesis of nanometer-sized particles of barium orthotitanate prepared through a modified reverse micellar route: Structural characterization, phase stability and dielectric properties

2004 ◽  
Vol 19 (10) ◽  
pp. 2905-2912 ◽  
Author(s):  
Tokeer Ahmad ◽  
Ashok K. Ganguli
Keyword(s):  
Martensitic Transition ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
X Ray ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Microscopic Studies ◽  
Size Of Particles ◽  
Reverse Micellar

Nanoparticles of barium orthotitanate (Ba2TiO4) was obtained using microemulsions (avoiding Ba-alkoxide). Powder x-ray diffraction studies of the powder after calcining at 800 °C resulted in a mixture of orthorhombic (70%) and monoclinic (30%) phases. The high-temperature orthorhombic form present at 800 °C was due to the small size of particles obtained by the reverse micellar route. Pure orthorhombic Ba2TiO4 was obtained on further sintering at 1000 °C with lattice parameters a = 6.101(2) Å, b =22.94(1) Å, c = 10.533(2) Å (space group, P21nb). The particle size obtained from x-ray line broadening studies and transmission electron microscopic studies was found to be 40–50 nm for the powder obtained after heating at 800 °C. Sintering at 1000 °C showed increase in grain size up to 150 nm. Our studies corroborate well with the presence of a martensitic transition in Ba2TiO4. The dielectric constant was found to be 40 for Ba2TiO4 (at 100 kHz) for samples sintered at 1000 °C. The dielectric loss obtained was low (0.06) at 100 kHz.

Double Periodicity Formation in EuTe/PbTe Superlattices

1995 ◽  
Vol 399 ◽  
Author(s):  
M. Shima ◽  
L. Salamanca-Riba ◽  
G. Springholz ◽  
G. Bauer
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Short Period ◽  
Short Period Superlattices

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.

Bicontinuous Cubic Phase as a Matrix for the Synthesis of Semiconductor Nanocrystallites

1996 ◽  
Vol 431 ◽  
Author(s):  
Jianping Yang ◽  
Syed Qadri ◽  
Banahalli Ratna
Keyword(s):  
Size Distribution ◽  
Cubic Phase ◽  
Lipid Matrix ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
X Ray ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Bicontinuous Cubic ◽  
First Time

AbstractBicontinuous cubic phase of lipid has been utilized for the first time as a matrix to synthesize II–VI (CdS) and IV–VI (PbS) semiconductor nanocrystallites. The nanoparticles were isolated from the lipid matrix and stabilized by capping with a thiol compound before purification. Two different sizes (2.3 nm and 3.0 nm) of CdS particles were prepared by varying the conditions of preparation. The size was determined by a combination of UV-vis absorption spectra and X-ray diffraction (XRD). The steep absorption edges of the two CdS samples indicate very narrow size distribution. XRD and transmission electron microscopic imaging of PbS nanocrystallites revealed that the size was 4.9 nm with nearly monodispersed size distribution.

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