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Title: The effect of diffusion in internal gradients on nuclear magnetic resonance transverse relaxation measurements

In the present work we study the internal gradient effects on diffusion attenuation of the echo train appearing in the well-known Carr-Purcell-Meiboom-Gill (CPMG) technique, extensively used for transverse relaxation measurements. Our investigations are carried out on two porous ceramics, prepared with the same amount of magnetic impurities (Fe{sub 2}O{sub 3}) but different pore sizes. It is shown that diffusion effects on the CPMG echo train attenuation are strongly influenced by the pore size for the same magnetic susceptibility of the two samples. The experimental results were compared with a theoretical model taking into account the limit of free or restricted diffusion on echo train attenuation. The NMR experiments were performed on water filled samples using a low-field NMR instrument. The porous ceramics were prepared using both the replica technique and the powder compression technique. Magnetic susceptibility measurements indicated close values of the susceptibility constant for the two samples whereas the SEM images indicated different pore sizes. The results reported here may have impact in the interpretation of NMR relaxation measurements of water in soils or concrete samples.
Authors:
;  [1] ;  [2]
  1. Technical University of Cluj-Napoca, Physics and Chemistry Department, Cluj-Napoca (Romania)
  2. Technical University of Cluj-Napoca, Physics and Chemistry Department, Cluj-Napoca, Romania and Babes Bolyai University, Raluca Ripan Chemistry Research Institute, Cluj-Napoca (Romania)
Publication Date:
OSTI Identifier:
22257173
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1565; Journal Issue: 1; Conference: PIM 2013: International conference on processes in isotopes and molecules, Cluj Napoca (Romania), 25-27 Sep 2013; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CERAMICS; COMPRESSION; DIFFUSION; FERRITES; MAGNETIC SUSCEPTIBILITY; NUCLEAR MAGNETIC RESONANCE; POROUS MATERIALS; RELAXATION; REPLICA TECHNIQUES; SCANNING ELECTRON MICROSCOPY