Measurement of the Apparent Diffusion Coefficient of Toluene by Quasielastic Neutron Scattering

1971 ◽  
Vol 54 (8) ◽  
pp. 3643-3645 ◽  
Author(s):  
D. J. Winfield
Keyword(s):  
Diffusion Coefficient ◽  
Apparent Diffusion Coefficient ◽  
Neutron Scattering ◽  
Apparent Diffusion ◽  
Quasielastic Neutron ◽  
Quasielastic Neutron Scattering

Self Diffusion in Liquid Titanium: Quasielastic Neutron Scattering and Molecular Dynamics Simulation

2009 ◽  
Vol 289-292 ◽  
pp. 609-614 ◽  
Author(s):  
Andreas Meyer ◽  
Jürgen Horbach ◽  
O. Heinen ◽  
Dirk Holland-Moritz ◽  
T. Unruh
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficient ◽  
Neutron Scattering ◽  
The Self ◽  
Dynamics Simulation ◽  
Self Diffusion ◽  
Quasielastic Neutron ◽  
Liquid Titanium ◽  
Quasielastic Neutron Scattering ◽  
Self Diffusion Coefficient

Self diffusion in liquid titanium was measured at 2000K by quasielastic neutron scattering (QNS) in combination with container less processing via electromagnetic levitation. At small wavenumbers q the quasielastic signal is dominated by incoherent scattering. Up to about 1.2 °A−1 the width of the quasielastic line exhibits a q2 dependence as expected for long range atomic transport, thus allowing to measure the self diffusion coefficient DTi. As a result the value DTi = (5.3± 0.2)× 10−9 m2s−1 was obtained.With a molecular dynamics (MD) computer simulation using an embedded atom model (EAM) for Ti, the self diffusion coefficient is determined from the mean square displacement as well as from the decay of the incoherent intermediate scattering function at different q. By comparing both methods, we show that the hydrodynamic prediction of a q2 dependence indeed extends up to about 1.2 °A−1. Since this result does not depend significantly on the details of the interatomic potential, our findings show that accurate values of self diffusion coefficients in liquid metals can be measured by QNS on an absolute scale.

Proton Diffusion in Strontium Cerate Ceramics studied by Quasielastic Neutron Scattering and Impedance Spectroscopy

1995 ◽  
Vol 50 (6) ◽  
pp. 539-548 ◽  
Author(s):  
Ch. Karmonik ◽  
R. Hempelmann ◽  
Th. Matzke ◽  
T. Springer
Keyword(s):  
Diffusion Coefficient ◽  
Impedance Spectroscopy ◽  
Neutron Scattering ◽  
Elevated Temperatures ◽  
Diffusion Mechanism ◽  
Proton Conductor ◽  
Proton Diffusion ◽  
Quasielastic Neutron ◽  
Quasielastic Neutron Scattering ◽  
Strontium Cerate

Abstract Perovskite structured strontium cerate doped with ytterbium and water, e.g. SrCe0.95Yb0.05 H0.02O2.985, is a well known proton conductor at elevated temperatures. We have studied its proton conductivity or diffusivity, respectively, by impedance spectroscopy, IS, and by quasielastic neutron scattering, QENS. While the former method yields a macroscopic proton diffusion coefficient, the latter method allows to elucidate the microscopic proton diffusion mechanism. It consists of a sequence of free diffusion and trapping/escape events with the Yb3+ ions acting as trapping centers. The self-diffusion coefficient obtained with QENS agrees with the conductivity diffusion coefficient obtained with IS.

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