Author index volume 40

Tracer diffusion coefficients for Li in glasses of albite, orthoclase, and obsidian composition have been determined by a method involving deposition of a thin source on polished glass wafers, anneal under controlled temperature conditions (300–900°C), and ion-microprobe determination of the concentration profile. All results conform to an Arrhenius-type relationship,D = D₀exp(?Q/RT), whereQ is 23, 17, and 22 kcal mol^?1;D₀ is 0.2, 0.003, and 0.03 cm²s^?1 for albite and orthoclase glasses, and obsidian respectively. Lithium is thus a fast diffusing ion and behaves similarly to sodium in the same glasses. A mechanism involving jumps of the diffusing ions through oxygen hexagonal rings is suggested by consideration of ionic radii ratio of alkali (H, Li, Na, K, Rb, and Cs) ions to the oxygen anions.