title: NMR and conductivity studies of the mixed glass former effect in lithium borophosphate glasses.
abstract: Alkali ion charge transport has been studied in a series of mixed glass former lithium borophosphate glasses of composition 0.33Li(2)O + 0.67[xB(2)O(3) + (1 - x)P(2)O(5)]. The entire concentration range, 0.0 ≤ x ≤ 1.0, from pure glassy Li(2)P(4)O(11) to pure glassy Li(2)B(4)O(7) has been examined while keeping the molar fraction of Li(2)O constant. Electrical conductivity measurements and nuclear magnetic resonance techniques such as spin relaxometry, line shape analysis, and stimulated-echo spectroscopy were used to examine the temperature and frequency dependence of the Li(+) ion motion over wide ranges of time scale and temperature. By accurately determining motional time scales and activation energies over the entire composition range the ion dynamics and the charge transport are found to be fastest if the borate and the phosphate fractions are similar. The nonlinear variation of the charge conduction, the most notable feature of the mixed glass former effect, is discussed in terms of the composition dependence of network former units which determine the local glass structure.
authors.affiliation: Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Storek
authors.forename: Roland
authors.initials: R
authors.lastname: Böhmer
authors.forename: Steve W
authors.initials: SW
authors.lastname: Martin
authors.forename: Dirk
authors.initials: D
authors.lastname: Larink
authors.forename: Hellmut
authors.initials: H
authors.lastname: Eckert
mesh_terms: D001896:Boron Compounds / Q000737:chemistry*; D004553:Electric Conductivity; D005898:Glass / Q000737:chemistry*; D018020:Lithium Compounds / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D010710:Phosphates / Q000737:chemistry*; D013696:Temperature
chemical_list: D001896:Boron Compounds; D018020:Lithium Compounds; D010710:Phosphates