Nuclear magnetic resonance and ionic motion in fluorozirconate glasses

Abstract

We have determined NMR linewidths and nuclear spin relaxation rates for F, Li, and Na nuclei, and electrical conductivity in ZrF 4-based fluoride glasses as a function of temperature. The results indicate that both Li and F are mobile in the glass containing 20 mole% LiF, whereas only F is mobile in glasses containing NaF (up to 30 mole%) or no alkali ions. Finally we compare and discuss the activation energies for the various parameters. RESUME Des mesures de conductivité électrique et de RMN de F, Li et Na ont e'te' re'alise'es sur des verres fluorures à base de ZrF 4 : les variations des largeurs de raies de résonance et des temps de relaxation ont été e'tudie'es en fonction de la température. Les résultats démontrent que les ions Li et F sont mobiles dans le verre contenant 20% de LiF(en fraction molaire). Dans le cas des verres contenant du NaF (jusqu'à 30% en mole) ou ne contenant pas de cation alcalin, seul l'ion F est mobile. Les e'nergies d'activation déduites des divers paramétres sont comparées et analysées.

Differential scanning calorimetry, x-ray diffraction and F19 nuclear magnetic resonance investigations of the crystallization of InF3-based glasses

“…Heat treatment at temperatures above T g enhances the nucleation of the first growing phases but has little influence on the following ones. XRD results show that several crystalline phases are formed, with solid state transitions when heated above 680 K. The 19 F NMR results show that the spin-lattice relaxation, for the glass samples heat treated above 638 K, is described by two time constants. For samples treated below this temperature a single time constant T 1 was observed.…”

“…Results of differential scanning calometry ͑DSC͒, x-ray diffraction ͑XRD͒, and 19 F nuclear magnetic resonance ͑NMR͒ of InF 3 -based glasses, treated at different temperatures, ranging from glass transition temperature (T g ) to crystallization temperature (T c ), are reported. The main features of the experimental results are as follows.…”

“…For samples treated below this temperature a single time constant T 1 was observed. Measurements of the 19 F spin-lattice relaxation time (T 1 ), as a function of temperature, made possible the identification of the mobile fluoride ions. The activation energy, for the ionic motion, in samples treated at crystallization temperature was found to be 0.18Ϯ0.01 eV.…”

“…The NMR 19 F relaxation times measurements were carried out at a frequency of 36 MHz, by means of a home built pulsed NMR spectrometer. Spin-lattice relaxation times were determined using the progressive saturation method.…”

Structural Role of Fluoride in the Ion-Conducting Glass System B2O3−PbO−LiF Studied by Single- and Double-Resonance NMR

“…During the past decades, the ion dynamics of metal halide-doped lithium borate and tellurite glasses have been characterized by detailed temperature-dependent line shape and spin-lattice relaxation rate measurements. [17][18][19][20][21][22][23] In general, the cations are found to be mobile, whereas the extent of anion mobility is often uncertain. In contrast to the detailed dynamical characterization, there is presently little information on the local structure of these materials.…”