In:
Zeitschrift für Physikalische Chemie, Walter de Gruyter GmbH, Vol. 226, No. 5-6 ( 2012-6-1), p. 461-489
Abstract:
Single crystals of titanium disulfide TiS 2 were synthesized by chemical vapor synthesis and subsequently intercalated with n-butyl lithium (BuLi) in n-hexane. Experiments were carried out using a butyl lithium concentration between 0.8 and 10 mol L -1 and the temperature range was from 248 K to 328 K. The duration of the intercalation was varied from 2 h to 30 d. After the intercalation experiments concentration profiles of lithium, titanium and sulfur were measured parallel to the ab-plane of the crystal by LA-ICP-OES (LASER Ablation — Inductively Coupled Plasma - Optical Emission Spectroscopy). Chemical diffusion coefficients ( D ) were determined by fitting of the profiles to the specific solution of Fick's 2 nd law for the given boundary conditions. The measured diffusivity in the ab-plane ( D || a/b ) varies between 10 -13 and 10 -15 m 2 s -1 at room temperature. These variations of D cannot be correlated to the reaction time. On the other hand a systematic increase of D || a/b with the concentration of butyl lithium ( c BuLi ) was observed, with a corresponding decrease in activation energy from 59.6 ± 7.6 kJ mol -1 ( c BuLi =1.6 mol L -1 ) to 42.6 ± 11.7 kJ mol -1 ( c BuLi =10 mol L -1 ). Furthermore, profiles measured on the same crystals reveal D || a/b values differing by up to a factor of 3. ToF-SIMS (Time-of-Flight Secondary Ion Mass Spectromety) images gave evidence of inhomogenous insertion of lithium along crystal edges. These findings indicate that stress induced by widening of the crystal layers plays a crucial role in the intercalation kinetics. SIMS profiling perpendicular to the ab-plane gives evidence that D ⊥ a /b is at least four orders of magnitude lower than D || a/b .
Type of Medium:
Online Resource
ISSN:
2196-7156
,
0942-9352
DOI:
10.1524/zpch.2012.0227
Language:
English
Publisher:
Walter de Gruyter GmbH
Publication Date:
2012
detail.hit.zdb_id:
201103-7
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