Structural unit charge density and molecular cation templating effects on orientational geometric isomerism and interlayer spacing in 2-D uranyl sulfates

The higher the charge density of PILs the higher their Tg and the lower their conductivity; the best conductivity (1.8 × 10−5 S cm−1 at 25 °C): PILs with triazolium cations; the best cathodic stability (−0.4 V vs. Li+/Li at 70 °C): PILs with mixed type cations.

Download Full-text

The Collagenic Molecular Structural Unit of Solid State Complexes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100066449 ◽

1971 ◽

Vol 29 ◽

pp. 478-479

Author(s):

Kenneth M. Richter ◽

John A. Schilling

Keyword(s):

Molecular Weight ◽

Solid State ◽

Structural Unit ◽

X Ray Diffraction ◽

X Ray ◽

Naoh Treatment

The structural unit of solid state collagen complexes has been reported by Porter and Vanamee via EM and by Cowan, North and Randall via x-ray diffraction to be an ellipsoidal unit of 210-270 A. length by 50-100 A. diameter. It subsequently was independently demonstrated by us in dog tendon, dermis, and induced complexes. Its detailed morphologic, dimensional and molecular weight (MW) aspects have now been determined. It is pear-shaped in long profile with m diameters of 57 and 108 A. and m length of 263 A. (Fig. 1, tendon, KMnO4 fixation, Na-tungstate; Fig. 2a, schematic of unit in long, C, and x-sectional profiles of its thin, xB, and bulbous, xA portions; Fig. 2b, tendon essentially unmodified by ether and 0.4 N NaOH treatment, Na-tungstate). The unit consists of a uniquely coild cable, c, of ṁ 22.9 A. diameter and length of 2580-3316 A. The cable consists of three 2nd-strands, s, each of m 10.6 A.

Download Full-text

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

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100120692 ◽

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.

Download Full-text