F centers in LiF: A nuclear magnetic resonance study

Abstract

PACS 61.82. Ms, 76.30.Mi, 76.60.Es Ionizing radiation like g-rays, electrons, or swift heavy ions create a variety of point defects in dielectric materials. The largest fraction of the defects consists of the paramagnetic F centers. Here, we study those F centers in LiF by nuclear magnetic resonance. Nuclear spin relaxation (T 1 ) measurements serve as a probe for the F centers offering the possibility to investigate their dynamics as a function of temperature and irradiation dose. Moreover, one is able to estimate the content of the paramagnetic defects from the T 1 -data over a wide range of concentration. We further observed and analyzed radiation annealing occurring at temperatures above 360 K.

Hardening in LiF induced by fast Ni ions and recovery of properties under annealing

“…4) yields activation energy of 0.13 eV ± 0.02 in the temperature range from 530 to 810 K. This value is close to activation energies for H center migration in LiF obtained by other authors [8,9]. In the case of F centers and their aggregates, the activation energy is known to be considerably higher (0.6-1.7 eV) [10,11]. The obtained result points to a possible role of interstitial halogen defects in the recovery processes.…”

Probing the defect nanostructure of helium and proton tracks in LiF:Mg,Ti using optical absorption: Implications to track structure theory calculations of heavy charged particle relative efficiency

“…Following HCP irradiation of single crystal LiF N Fmax is significantly greater. The many possible reasons for the enhanced production of vacancies/F centers following HCP irradiation are discussed elsewhere [1][2][3][4][5][6][7][8]38,42,[46][47][48][49][51][52][53]. In single crystal LiF following LID irradiation only the 5.08 eV and 4.77 eV OA bands are observed confirming that the 4.0 eV and 5.45 eV OA bands are dopant-related.…”

“…In this range of levels of dose the F center dose response is sub-linear and proportional to D a (0.5 < a < 0.8) [51][52][53]. Other measurements on LiF:Mg,Ti samples were carried out without decomposition of the OA spectra [54].…”

Combining 7Li NMR field-cycling relaxometry and stimulated-echo experiments: A powerful approach to lithium ion dynamics in solid-state electrolytes

“…Previously, feasibility of 7 Li FFC was demonstrated, but application was limited to a characterization of paramagnetic defects in a crystal [42]. We showed that 7 Li FFC provides straightforward access to the lithium ionic motion in a frequency range of 10 5 -10 9 s À 1 and, hence, in a time range of 10 À 9 -10 À 5 s. The lower limit of the frequency range results from the breakdown of conventional perturbation theory when the ZE interaction becomes weaker than the QP interaction, while the upper limit is determined by the available strength of the magnetic field.…”

“…While we will be able to exploit that 7 Li NMR STE experiments developed into a routine technique, we will have to establish 7 Li NMR FFC measurements as a new method for investigations of lithium ion dynamics in solids. Previously, the feasibility of 7 Li NMR FFC was demonstrated, but application was limited to an analysis of paramagnetic defects in LiF crystals [42]. The benefits of a combination of FFC and STE techniques will be shown for a (Li 2 S)-(P 2 S 5 ) glass.…”