INVESTIGADORES
VACA CHAVEZ FORNASERO Fabian
artículos
Título:
Fast Field Cycling NMR Study in Ferrofluids and Ferronematic Materials
Autor/es:
DANIEL PUSIOL; FABIAN VACA CHAVEZ; MIKLOS ZRINYI; ANTONIO FIGUEIREDO NETO
Revista:
ANNALS OF MAGNETIC RESONANCE
Editorial:
AUREMN
Referencias:
Año: 2004 vol. 3 p. 22 - 23
ISSN:
1519-8308
Resumen:
The molecular dynamics of the carrying liquid in ferrofluid and ferronematic
materials is investigated by fast field cycling NMR. Spin-lattice relaxation dispersion profiles in
magnetic nanoparticles doped 5CB in different relative concentrations are measured as a function of
temperature. The same study is carried out in aqueous ionic ferrofluid. From the comparison of the
behaviours we conclude that due to the huge magnetic field gradients in the intergrain region (~10-4
T/m) the translational mobility of the liquid crystal molecules is restricted. That effect is not observed
for water molecules in the ferrofluid material. Calculation of the magnetic forces for the water
molecules of the ferrofluid in those regions gives energies slightly below kBT. The same calculation
with 5CB-molecules magnetic moment gives higher magnetic energies; in this case, thermal agitation
is not enough to establish a freedom random- walk diffusion.