Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Nuclear magnetic resonance clustering

Measurements of NMR for Ti, Ti [33], and Sr [34,35] were carried out for STO 16 and STO 18-96. Ti and Sr nuclear magnetic resonance spectra provide direct evidence for Ti disorder even in the cubic phase and show that the ferroelectric transition at Tc = 25 K occurs in two steps. Below 70 K, rhomb ohedral polar clusters are formed in the tetragonal matrix. These clusters subsequently grow in concentration, freeze out, and percolate, leading to an inhomogeneous ferroelectric state below Tc. This shows that the elusive ferroelectric transition in STO 18 is indeed connected with local symmetry lowering and impHes the existence of an order-disorder component in addition to the displacive soft mode [33-35]. Rhombohedral clusters, Ti disorder, and a two-component state are found in the so-called quantum paraelectric... [Pg.115]

Nuclear magnetic resonance spectroscopy, 46 161-162, see also specific compounds of alkyne-substituted clusters... [Pg.209]

Thanks to the extensive literature on Aujj and the related smaller gold cluster compounds, plus some new results and reanalysis of older results to be presented here, it is now possible to paint a fairly consistent physical picture of the AU55 cluster system. To this end, the results of several microscopic techniques, such as Extended X-ray Absorption Fine Structure (EXAFS) [39,40,41], Mossbauer Effect Spectroscopy (MES) [24, 25, 42,43,44,45,46], Secondary Ion Mass Spectrometry (SIMS) [35, 36], Photoemission Spectroscopy (XPS and UPS) [47,48,49], nuclear magnetic resonance (NMR) [29, 50, 51], and electron spin resonance (ESR) [17, 52, 53, 54] will be combined with the results of several macroscopic techniques, such as Specific Heat (Cv) [25, 54, 55, 56,49], Differential Scanning Calorimetry (DSC) [57], Thermo-gravimetric Analysis (TGA) [58], UV-visible absorption spectroscopy [40, 57,17, 59, 60], AC and DC Electrical Conductivity [29,61,62, 63,30] and Magnetic Susceptibility [64, 53]. This is the first metal cluster system that has been subjected to such a comprehensive examination. [Pg.3]

APPENDIX I NUCLEAR MAGNETIC RESONANCE SPECTROSCOPIC DATA AND AVAILABILITY OF STRUCTURAL DATA FOR METALLOBORANE CLUSTERS WITH A RATIO OF M AND B ATOMS OF AT LEAST 1 1... [Pg.37]

Polypeptide Fold in the Two Metal Clusters of Metallothionein-2 by Nuclear Magnetic Resonance and Distance Geometry. [Pg.168]

See other pages where Nuclear magnetic resonance clustering is mentioned: [Pg.301]    [Pg.1132]    [Pg.184]    [Pg.328]    [Pg.218]    [Pg.65]    [Pg.25]    [Pg.407]    [Pg.409]    [Pg.438]    [Pg.4]    [Pg.228]    [Pg.538]    [Pg.190]    [Pg.457]    [Pg.334]    [Pg.597]    [Pg.416]    [Pg.168]    [Pg.44]    [Pg.312]    [Pg.174]    [Pg.55]    [Pg.10]    [Pg.392]    [Pg.394]    [Pg.252]    [Pg.293]    [Pg.20]    [Pg.28]    [Pg.451]    [Pg.247]    [Pg.89]    [Pg.1012]    [Pg.224]    [Pg.192]    [Pg.34]    [Pg.126]    [Pg.185]    [Pg.1132]   
See also in sourсe #XX -- [ Pg.107 , Pg.108 , Pg.109 ]



SEARCH



Cluster nuclearity

Clusters magnetic

Clusters magnetism

Iron-sulfur cluster nuclear magnetic resonance

© 2024 chempedia.info