‘‘Ordered’’ structure in dilute suspensions of polymer latices as studied by microscopy. Influences of charge density and size

1986 ◽  
Vol 85 (10) ◽  
pp. 6143-6146 ◽  
Author(s):  
Kensaku Ito ◽  
Hiroshi Nakamura ◽  
Norio Ise
Keyword(s):  
Charge Density ◽  
Ordered Structure ◽  
Polymer Latices ◽  
Dilute Suspensions

Electroviscous effect in dilute suspensions of ionic polymer latices

1993 ◽  
Vol 30 (2) ◽  
pp. 233-236 ◽  
Author(s):  
J. Yamanaka ◽  
S. Hashimoto ◽  
T. Yamaguchi ◽  
S. Saeki ◽  
M. Tsubokawa ◽  
...  
Keyword(s):  
Ionic Polymer ◽  
Electroviscous Effect ◽  
Polymer Latices ◽  
Dilute Suspensions

Planar defects in ordered (Ga,In)P

1988 ◽  
Vol 46 ◽  
pp. 902-903
Author(s):  
S. McKernan ◽  
C. B. Carter ◽  
D. Bour ◽  
J. R. Shealy
Keyword(s):  
Electron Diffraction ◽  
Vapor Phase ◽  
Growth Direction ◽  
High Density ◽  
Ordered Structure ◽  
Planar Defects ◽  
Diffraction Patterns ◽  
Ternary Semiconductors ◽  
Anion Species ◽  
Metallic Vapor

The growth of ternary III-V semiconductors by organo-metallic vapor phase epitaxy (OMVPE) is widely practiced. It has been generally assumed that the resulting structure is the same as that of the corresponding binary semiconductors, but with the two different cation or anion species randomly distributed on their appropriate sublattice sites. Recently several different ternary semiconductors including AlxGa1-xAs, Gaxln-1-xAs and Gaxln1-xP1-6 have been observed in ordered states. A common feature of these ordered compounds is that they contain a relatively high density of defects. This is evident in electron diffraction patterns from these materials where streaks, which are typically parallel to the growth direction, are associated with the extra reflections arising from the ordering. However, where the (Ga,ln)P epilayer is reasonably well ordered the streaking is extremely faint, and the intensity of the ordered spot at 1/2(111) is much greater than that at 1/2(111). In these cases it is possible to image relatively clearly many of the defects found in the ordered structure.

Incommensurate modulated phases of the NbxTa1-xTe4 charge density wave system

1992 ◽  
Vol 50 (1) ◽  
pp. 58-59
Author(s):  
S. Ritchie ◽  
J. C. Bennett ◽  
A. Prodan ◽  
F.W. Boswell ◽  
J.M. Corbett
Keyword(s):  
Charge Density ◽  
Charge Density Wave ◽  
Direct Evidence ◽  
Density Wave ◽  
Wave System ◽  
Modulated Phases ◽  
Metal Atoms ◽  
Incommensurate Modulation ◽  
End Members ◽  
Modulation Wave Vector

A continuous sequence of compounds having composition NbxTa1-xTe4; 0 ≤ x ≤ 1 have been studied by electron diffraction and microscopy. Previous studies have shown that the end members of the series, TaTε4 and NbTε4 possess a quasi-one-dimensional character and exhibit charge density wave (CDW) distortions. In these compounds, the subcell structure is tetragonal with axes (a × a × c) and consists of the metal atoms (Nb or Ta) centered within an extended antiprismatic cage of Te atoms. At room temperature, TaTε4 has a commensurate modulation structure with a 2a × 2a × 3c unit cell. In NbTε4, an incommensurate modulation with × ∼ 16c axes is observed. Preliminary studies of the mixed compounds NbxTα1-xTε4 showed a discontinuous jump of the modulation wave vector commensurate to incommensurate when the Nb dopant concentration x, exceeded x ≃ 0.3, In this paper, the nature of the compositional dependence of is studied in greater detail and evidence is presented for a stepwise variation of . This constitutes the first direct evidence for a Devil's staircase in CDW materials.

Characterisation of planar crystal defects in Y2Fe17Cx (0.6 ≤ x ≤ 1.6) magnetic material by High Resolution Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 774-775
Author(s):  
W. Coene ◽  
F. Hakkens ◽  
T.H. Jacobs ◽  
K.H.J. Buschow
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Permanent Magnets ◽  
Annealing Treatment ◽  
High Resolution Electron Microscopy ◽  
Crystal Defects ◽  
Ordered Structure ◽  
X Ray ◽  
Planar Crystal ◽  
Resolution Electron

Intermetallic compounds of the type RE2Fe17Cx (RE= rare earth element) are promising candidates for permanent magnets. In case of Y2Fe17Cx, the Curie temperature increases from 325 K for x =0 to 550 K for x = 1.6 . X ray and electron diffraction reveal a carbon - induced structural transformation in Y2Fe17Cx from the hexagonal Th2Ni17 - type (x < 0.6 ) to the rhombohedral Th2Zn17 - type ( x ≥ 0.6). Planar crystal defects introduce local sheets of different magnetic anisotropy as compared with the ordered structure, and therefore may have an important impact on the coercivivity mechanism .High resolution electron microscopy ( HREM ) on a Philips CM30 / Super Twin has been used to characterize planar crystal defects in rhombohedral Y2Fe17Cx ( x ≥ 0.6 ). The basal plane stacking sequences are imaged in the [100] - orientation, showing an ABC or ACB sequence of Y - atoms and Fe2 - dumbbells, for both coaxial twin variants, respectively . Compounds resulting from a 3 - week annealing treatment at high temperature ( Ta = 1000 - 1100°C ) contain a high density of planar defects.

Wave Analysis of the Charge Density Wave Dynamics in the Molecular Conductor (Perylene)2Pt(mnt)2 (mnt=maleonitriledithiolate)

1995 ◽  
Vol 5 (5) ◽  
pp. 539-545 ◽  
Author(s):  
J. Dumas ◽  
N. Thirion ◽  
M. Almeida ◽  
E. B. Lopes ◽  
M. J. Matos ◽  
...  
Keyword(s):  
Charge Density ◽  
Charge Density Wave ◽  
Density Wave ◽  
Wave Analysis ◽  
Wave Dynamics ◽  
Molecular Conductor

Macroscopic quantum tunneling of charge density waves

1999 ◽  
Vol 09 (PR10) ◽  
pp. Pr10-161-Pr10-163
Author(s):  
H. Matsukawa ◽  
H. Miyake ◽  
M. Yumoto ◽  
H. Fukuyama
Keyword(s):  
Charge Density ◽  
Quantum Tunneling ◽  
Charge Density Waves ◽  
Density Waves ◽  
Macroscopic Quantum ◽  
Macroscopic Quantum Tunneling

Phase slip scaling relationship for the 59 K and 143 K charge-density-waves in NbSe3

1999 ◽  
Vol 09 (PR10) ◽  
pp. Pr10-129-Pr10-132 ◽  
Author(s):  
J. P. McCarten ◽  
T. C. Jones ◽  
X. Wu ◽  
J. H. Miller ◽  
I. Pirtle ◽  
...  
Keyword(s):  
Charge Density ◽  
Charge Density Waves ◽  
Phase Slip ◽  
Density Waves ◽  
Scaling Relationship
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