Nuclear magnetic resonance study of proton conductor HPb2Nb3O10. nH2O. / Estudo por Ressonância Magnética Nuclear do Condutor Protônico HPb2Nb3O10. nH2O.

AUTOR(ES)

Caio Eduardo de Campos Tambelli

DATA DE PUBLICAÇÃO

1998

RESUMO

The protonic conductor HPb2Nb3O10. nH2O , was studied by pulsed Nuclear Magnetic Resonance (NMR) of ANTPOT.1H. The temperature dependence of the spin-lattice relaxation rate (1/T IND.1) and line width, reflect the mobility of the protonic species present in this material. The onset of ionic and molecular motions produces a strong narrowing of the line at temperatures above 130 K. The spin-lattice relaxation data, obtained above 200 K, shows a maximum in 1/T IND.1, peaking in the range 253 K to 273 K, depending on the value of n. Activation energies of protonic motions, measured from line width and relaxation data, are n dependent and lies in the range of 0,14 eV to 0,4 eV. Results of NMR and conductivity are consistent with the Grotthus conduction mechanism, consisting of a succession of molecular re-orientations and proton jumps. The protonic diffusion coefficient was estimated from the parameters obtained from NMR relaxation and found to be of the order of 10-8 cm2/s, leading to a conductivity of about 10-3 S/ cm.

ASSUNTO(S)

condutor protônico nuclear magnetic resonance ressonância magnética nuclear proton conductor

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